@article{miao_tvcg_2018, title = "Multiscale Visualization and Scale-adaptive Modification of DNA Nanostructures", author = "Haichao Miao and Elisa De Llano and Johannes Sorger and Yasaman Ahmadi and Tadija Kekic and Tobias Isenberg and Eduard Gr\"{o}ller and Ivan Barisic and Ivan Viola", year = "2018", month = jan, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "24", number = "1", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/miao_tvcg_2018/", } @article{lawonn-2018-illvisstar, title = "A Survey of Surface-Based Illustrative Rendering for Visualization", author = "Kai Lawonn and Ivan Viola and Bernhard Preim and Tobias Isenberg", year = "2018", doi = "10.1111/cgf.13322", issn = "1467-8659", journal = "Computer Graphics Forum", number = "NN", pages = "n/a–n/a", keywords = "scientific visualization, visualization, Categories and SubjectDescriptors (according to ACM CCS): I.3.3 [Computer Graphics]:Picture/Image GenerationLine and curve generation", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/lawonn-2018-illvisstar/", } @talk{sbert-2017-sa_course_0023, title = "Information Theory In Visualization", author = "Mateu Sbert and Han-Wei Shen and Ivan Viola and Min Chen and Anton Bardera and Miquel Feixas", year = "2017", month = nov, event = "SIGGRAPH Asia 2017 Course 0023", location = "Bangkok, Thailand", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/sbert-2017-sa_course_0023/", } @misc{Groeller-2017-PTPMD, title = "AnimoAminoMiner: Exploration of Protein Tunnels and their Properties in Molecular Dynamics", author = "Jan Byska and Mathieu Le Muzic and Eduard Gr\"{o}ller and Ivan Viola and Barbora Kozlikova", year = "2017", month = jul, event = "BioVis@ISMB 2017", Conference date = "Poster presented at BioVis@ISMB 2017 (2017-07-24)", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/Groeller-2017-PTPMD/", } @misc{kouril-2017-sccgposter, title = "Maya2cellVIEW: Integrated Tool for Creating Large and Complex Molecular Scenes", author = "David Kou\v{r}il and Mathieu Le Muzic and Barbora Kozlikova and Ivan Viola", year = "2017", month = may, event = "Spring Conference on Computer Graphics 2017", Conference date = "Poster presented at Spring Conference on Computer Graphics 2017 (2017-05)", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/kouril-2017-sccgposter/", } @inproceedings{sorger_2017_metamorphers, title = "Metamorphers: Storytelling Templates For Illustrative Animated Transitions in Molecular Visualization", author = "Johannes Sorger and Peter Mindek and Peter Rautek and Eduard Gr\"{o}ller and Graham Johnson and Ivan Viola", year = "2017", abstract = "In molecular biology, illustrative animations are used to convey complex biological phenomena to broad audiences. However, such animations have to be manually authored in 3D modeling software, a time consuming task that has to be repeated from scratch for every new data set, and requires a high level of expertise in illustration, animation, and biology. We therefore propose metamorphers: a set of operations for defining animation states as well as the transitions to them in the form of re-usable story telling templates. The re-usability is two-fold. Firstly, due to their modular nature, metamorphers can be re-used in different combinations to create a wide range of animations. Secondly, due to their abstract nature, metamorphers can be re-used to re-create an intended animation for a wide range of compatible data sets. Metamorphers thereby mask the low level complexity of explicit animation specifications by exploiting the inherent properties of the molecular data, such as the position, size, and hierarchy level of a semantic data subset.", month = may, location = "Mikulov, Czech Republic", booktitle = "Proceedings of the Spring Conference on Computer Graphics 2017", pages = "27--36", keywords = "animated transitions, storytelling, molecular visualization", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/sorger_2017_metamorphers/", } @inproceedings{Gehrer-2017-molmach, title = "Visualization of molecular machinery using agent-based animation", author = "Daniel Gehrer and Ivan Viola", year = "2017", month = may, event = "Spring Conference on Computer Graphics", booktitle = "Proceedings of SCCG 2017", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/Gehrer-2017-molmach/", } @article{Waldin_Nicholas_2017_FlickerObserver, title = "Flicker Observer Effect: Guiding Attention Through High Frequency Flicker in Images", author = "Nicholas Waldin and Manuela Waldner and Ivan Viola", year = "2017", abstract = "Drawing the user's gaze to an important item in an image or a graphical user interface is a common challenge. Usually, some form of highlighting is used, such as a clearly distinct color or a border around the item. Flicker can also be very salient, but is often perceived as annoying. In this paper, we explore high frequency flicker (60 to 72 Hz) to guide the user's attention in an image. At such high frequencies, the critical flicker frequency (CFF) threshold is reached, which makes the flicker appear to fuse into a stable signal. However, the CFF is not uniform across the visual field, but is higher in the peripheral vision at normal lighting conditions. Through experiments, we show that high frequency flicker can be easily detected by observers in the peripheral vision, but the signal is hardly visible in the foveal vision when users directly look at the flickering patch. We demonstrate that this property can be used to draw the user's attention to important image regions using a standard high refresh-rate computer monitor with minimal visible modifications to the image. In an uncalibrated visual search task, users could in a crowded image easily spot the specified search targets flickering with very high frequency. They also reported that high frequency flicker was distracting when they had to attend to another region, while it was hardly noticeable when looking at the flickering region itself.", month = may, journal = "Computer Graphics Forum", volume = "36", number = "2", pages = "467--476", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/Waldin_Nicholas_2017_FlickerObserver/", } @inproceedings{seyfert-2017, title = "Dynamic word clouds", author = "Ivan Viola and Martin Seyfert", year = "2017", abstract = "Using word clouds to visualize dynamic time-varying data is a field still under-explored. The goal of our approach is to provide a novel way of generating smoothly animated word clouds to show changes in word frequency via font size. Unlike existing methods, a compact layout, inspired by the popular word cloud generation tool Wordle, is preserved during animation and implemented using web technologies.Word size changes in time are also illustrated via color and word rotation. ", month = may, isbn = "978-1-4503-5107-2", location = "Mikulov", event = "SCCG 2017", editor = "ACM", doi = "10.1145/3154353.3154358", booktitle = "Proceedings of SCCG 2017", keywords = " tag cloud, animated, dynamic, time-varying, word cloud ", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/seyfert-2017/", } @misc{mindek-2017-virtualcell, title = "The Birth of a Virtual Cell", author = "Peter Mindek and Johannes Sorger and David Kou\v{r}il and Tobias Klein and Graham Johnson and Ivan Viola", year = "2017", abstract = "In our current research project, we are working on the interactive visualization of cellular data at multiple scales. The visual story telling contest motivated us to describe the process of bringing this complex volumetric data "to life". We scripted the visual story directly within the current build of our multi-scale visualization. The entire video is therefore rendered in real time. This enabled us to directly show the steps involved in the rendering of our final visualization based on the actual data and the actual algorithms that are applied. The various effects in the video are therefore parameter variables for existing multi-scale visualization functions that change over time. The final result of our visualization was inspired by a rendering of the reference 3D model that was created by a scientific illustrator. The challenge that we overcome in our visualization was to create a rendering of the original data at stable 30 frames per second that matches the offline rendered illustration in visual quality, which helps to clarify the complex 3D arrangements of the inner components of the cell.", month = apr, note = "submitted to the Pacific Vis 2017 Storytelling Contest", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/mindek-2017-virtualcell/", } @article{Kolesar-Fractional-2016, title = "A Fractional Cartesian Composition Model for Semi-Spatial ComparativeVisualization Design", author = "Ivan Koles\'{a}r and Stefan Bruckner and Ivan Viola and Helwig Hauser", year = "2017", month = jan, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "23", number = "1", doi = "10.1109/TVCG.2016.2598870", pages = "851-860", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/Kolesar-Fractional-2016/", } @article{Viola-Pondering-2017, title = "Pondering the Concept of Abstraction in (Illustrative) Visualization", author = "Ivan Viola and Tobias Isenberg", year = "2017", abstract = "We explore the concept of abstraction as it is used in visualization, with the ultimate goal of understanding and formally defining it. Researchers so far have used the concept of abstraction largely by intuition without a precise meaning. This lack of specificity left questions on the characteristics of abstraction, its variants, its control, or its ultimate potential for visualization and, in particular, illustrative visualization mostly unanswered. In this paper we thus provide a first formalization of the abstraction concept and discuss how this formalization affects the application of abstraction in a variety of visualization scenarios. Based on this discussion, we derive a number of open questions still waiting to be answered, thus formulating a research agenda for the use of abstraction for the visual representation and exploration of data. This paper, therefore, is intended to provide a contribution to the discussion of the theoretical foundations of our field, rather than attempting to provide a completed and final theory.", month = sep, journal = "IEEE Transactions on Visualization and Computer Graphics", number = "99", doi = "10.1109/TVCG.2017.2747545", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/Viola-Pondering-2017/", } @article{klein_2017_IM, title = "Instant Construction and Visualization of Crowded Biological Environments", author = "Tobias Klein and Ludovic Autin and Barbora Kozlikova and David Goodsell and Arthur Olson and Eduard Gr\"{o}ller and Ivan Viola", year = "2018", abstract = "We present the first approach to integrative structural modeling of the biological mesoscale within an interactive visual environment. These complex models can comprise up to millions of molecules with defined atomic structures, locations, and interactions. Their construction has previously been attempted only within a non-visual and non-interactive environment. Our solution unites the modeling and visualization aspect, enabling interactive construction of atomic resolution mesoscale models of large portions of a cell. We present a novel set of GPU algorithms that build the basis for the rapid construction of complex biological structures. These structures consist of multiple membrane-enclosed compartments including both soluble molecules and fibrous structures. The compartments are defined using volume voxelization of triangulated meshes. For membranes, we present an extension of the Wang Tile concept that populates the bilayer with individual lipids. Soluble molecules are populated within compartments using the Halton sequence for their distribution. Fibrous structures, such as RNA or actin filaments, are created by self-avoiding random walks. Resulting overlaps of molecules are resolved by a forced-based system. Our approach opens new possibilities to the world of interactive construction of cellular compartments. We demonstrate its effectiveness by showcasing scenes of different scale and complexity that comprise blood plasma, mycoplasma, and HIV.", journal = "IEEE Transactions on Visualization and Computer Graphics", doi = "10.1109/TVCG.2017.2744258", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/klein_2017_IM/", } @article{mindek-2017-marion, title = "Visualization Multi-Pipeline for Communicating Biology", author = "Peter Mindek and David Kou\v{r}il and Johannes Sorger and David Toloudis and Blair Lyons and Graham Johnson and Eduard Gr\"{o}ller and Ivan Viola", year = "2017", abstract = "We propose a system to facilitate biology communication by developing a pipeline to support the instructional visualization of heterogeneous biological data on heterogeneous user-devices. Discoveries and concepts in biology are typically summarized with illustrations assembled manually from the interpretation and application of heterogenous data. The creation of such illustrations is time consuming, which makes it incompatible with frequent updates to the measured data as new discoveries are made. Illustrations are typically non-interactive, and when an illustration is updated, it still has to reach the user. Our system is designed to overcome these three obstacles. It supports the integration of heterogeneous datasets, reflecting the knowledge that is gained from different data sources in biology. After pre-processing the datasets, the system transforms them into visual representations as inspired by scientific illustrations. As opposed to traditional scientific illustration these representations are generated in real-time - they are interactive. The code generating the visualizations can be embedded in various software environments. To demonstrate this, we implemented both a desktop application and a remote-rendering server in which the pipeline is embedded. The remote-rendering server supports multi-threaded rendering and it is able to handle multiple users simultaneously. This scalability to different hardware environments, including multi-GPU setups, makes our system useful for efficient public dissemination of biological discoveries. ", journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "24", number = "1", keywords = "Biological visualization, remote rendering, public dissemination", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/mindek-2017-marion/", } @inproceedings{vad_viktor-2017-WVE, title = "Watergate: Visual Exploration of Water Trajectories in Protein Dynamics", author = "Viktor Vad and Jan Byska and Adam Jurcik and Ivan Viola and Eduard Gr\"{o}ller and Helwig Hauser and Sergio M. Margues and Jiri Damborsky and Barbora Kozlikova", year = "2017", abstract = "The function of proteins is tightly related to their interactions with other molecules. The study of such interactions often requires to track the molecules that enter or exit specific regions of the proteins. This is investigated with molecular dynamics simulations, producing the trajectories of thousands of water molecules during hundreds of thousands of time steps. To ease the exploration of such rich spatio-temporal data, we propose a novel workflow for the analysis and visualization of large sets of water-molecule trajectories. Our solution consists of a set of visualization techniques, which help biochemists to classify, cluster, and filter the trajectories and to explore the properties and behavior of selected subsets in detail. Initially, we use an interactive histogram and a time-line visualization to give an overview of all water trajectories and select the interesting ones for further investigation. Further, we depict clusters of trajectories in a novel 2D representation illustrating the flows of water molecules. These views are interactively linked with a 3D representation where we show individual paths, including their simplification, as well as extracted statistical information displayed by isosurfaces. The proposed solution has been designed in tight collaboration with experts to support specific tasks in their scientific workflows. They also conducted several case studies to evaluate the usability and effectiveness of our new solution with respect to their research scenarios. These confirmed that our proposed solution helps in analyzing water trajectories and in extracting the essential information out of the large amount of input data.", location = "September, 2017 Bremen, Germany", booktitle = "Eurographics Workshop on Visual Computing for Biology and Medicine 2017", pages = "33--42", URL = "https://www.cg.tuwien.ac.at/research/publications/2017/vad_viktor-2017-WVE/", } @article{Kozlikova-Visualization-2016b, title = "Visualization of Biomolecular Structures: State of the Art Revisited", author = "Barbora Kozlikova and Michael Krone and Martin Falk and Norbert Lindow and Daniel Baum and Ivan Viola and Marc Baaden and Julius Parulek and Hans-Christian Hege", year = "2016", month = nov, doi = "10.1111/cgf.13072", journal = "Computer Graphics Forum", number = "XX", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Kozlikova-Visualization-2016b/", } @inproceedings{sorger-2016-fowardabstraction, title = "Illustrative Transitions in Molecular Visualization via Forward and Inverse Abstraction Transform", author = "Johannes Sorger and Peter Mindek and Tobias Klein and Graham Johnson and Ivan Viola", year = "2016", abstract = "A challenging problem in biology is the incompleteness of acquired information when visualizing biological phenomena. Structural biology generates detailed models of viruses or bacteria at different development stages, while the processes that relate one stage to another are often not clear. Similarly, the entire life cycle of a biological entity might be available as a quantitative model, while only one structural model is available. If the relation between two models is specified at a lower level of detail than the actual models themselves, the two models cannot be interpolated correctly. We propose a method that deals with the visualization of incomplete data information in the developmental or evolutionary states of biological mesoscale models, such as viruses or microorganisms. The central tool in our approach is visual abstraction. Instead of directly interpolating between two models that show different states of an organism, we gradually forward transform the models into a level of visual abstraction that matches the level of detail of the modeled relation between them. At this level, the models can be interpolated without conveying false information. After the interpolation to the new state, we apply the inverse transformation to the model’'s original level of abstraction. To show the flexibility of our approach, we demonstrate our method on the basis of molecular data, in particular data of the HIV virion and the mycoplasma bacterium.", month = sep, organization = "Eurographics", location = "Bergen", editor = "S. Bruckner, B. Preim, and A. Vilanova", booktitle = "Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM)", pages = "21--30", keywords = "I.3.3 [Computer Graphics]: Picture/Image Generation-Display algorithms", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/sorger-2016-fowardabstraction/", } @article{Kehl-Direct-2016, title = "Direct Image-to-Geometry Registration Using Mobile Sensor Data", author = "Christian Kehl and Simon Buckley and Robert Gawthorpe and Ivan Viola and John Anthony Howell ", year = "2016", month = jul, journal = "ISPRS Annals of Photogrammetry, Remote Sensing and Spatial InformationSciences", volume = "III-2", doi = "10.5194/isprs-annals-III-2-121-2016", pages = "121–128", pages = "121--128", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Kehl-Direct-2016/", } @article{bernhard-2016-gft, title = " The Accuracy of Gauge-Figure Tasks in Monoscopic and Stereo Displays", author = "Matthias Bernhard and Manuela Waldner and Pascal Plank and Veronika Solteszova and Ivan Viola", year = "2016", abstract = "The gauge-figure task (GFT) is a widespread method used to study surface perception for evaluating rendering and visualization techniques. The authors investigate how accurately slant angles probed on well-defined objects align with the ground truth (GT) in monoscopic and stereoscopic displays. Their results show that the GFT probes taken with well-defined objects align well with the GT in the all-monoscopic and all-stereoscopic conditions. However, they found that a GF rendered in stereo over a monoscopic stimulus results in a strong slant underestimation and that an overestimation occurred in the inverse case (monoscopic GF andstereoscopic stimulus). They discuss how their findings affect the interpretation of absolute GFT measures, compared to the GT normal.", month = jul, journal = "IEEE Computer Graphics and Applications", number = "4", volume = "36", pages = "56--66", keywords = "computer graphics, gauge-figure task, perceptual visualization, shape perception", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/bernhard-2016-gft/", } @article{Viola_Ivan_2015_AAM, title = "AnimoAminoMiner: Exploration of Protein Tunnels and their Properties in Molecular Dynamics", author = "Jan Byska and Mathieu Le Muzic and Eduard Gr\"{o}ller and Ivan Viola and Barbora Kozlikova", year = "2016", abstract = "In this paper we propose a novel method for the interactive exploration of protein tunnels. The basic principle of our approach is that we entirely abstract from the 3D/4D space the simulated phenomenon is embedded in. A complex 3D structure and its curvature information is represented only by a straightened tunnel centerline and its width profile. This representation focuses on a key aspect of the studied geometry and frees up graphical estate to key chemical and physical properties represented by surrounding amino acids. The method shows the detailed tunnel profile and its temporal aggregation. The profile is interactively linked with a visual overview of all amino acids which are lining the tunnel over time. In this overview, each amino acid is represented by a set of colored lines depicting the spatial and temporal impact of the amino acid on the corresponding tunnel. This representation clearly shows the importance of amino acids with respect to selected criteria. It helps the biochemists to select the candidate amino acids for mutation which changes the protein function in a desired way. The AnimoAminoMiner was designed in close cooperation with domain experts. Its usefulness is documented by their feedback and a case study, which are included.", month = jan, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "22", number = "1", issn = "1077-2626", pages = "747--756", keywords = "aggregation, molecular dynamics, Protein, interaction, tunnel", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Viola_Ivan_2015_AAM/", } @book{Chen-Information-2016, title = "Information Theory Tools for Visualization", author = "Min Chen and Miquel Feixas and Ivan Viola and Anton Bardera and Mateu Sbert and Han Wei Shen", year = "2016", isbn = "9781498740937", pages = "194", publisher = "CRC Press", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Chen-Information-2016/", } @inproceedings{Waldin_Nicholas_2016_Chameleon, title = "Chameleon Dynamic Color Mapping for Multi-Scale Structural Biology Models", author = "Nicholas Waldin and Mathieu Le Muzic and Manuela Waldner and Eduard Gr\"{o}ller and David Goodsell and Ludovic Autin and Ivan Viola", year = "2016", abstract = "Visualization of structural biology data uses color to categorize or separate dense structures into particular semantic units. In multiscale models of viruses or bacteria, there are atoms on the finest level of detail, then amino-acids, secondary structures, macromolecules, up to the compartment level and, in all these levels, elements can be visually distinguished by color. However, currently only single scale coloring schemes are utilized that show information for one particular scale only. We present a novel technology which adaptively, based on the current scale level, adjusts the color scheme to depict or distinguish the currently best visible structural information. We treat the color as a visual resource that is distributed given a particular demand. The changes of the color scheme are seamlessly interpolated between the color scheme from the previous views into a given new one. With such dynamic multi-scale color mapping we ensure that the viewer is able to distinguish structural detail that is shown on any given scale. This technique has been tested by users with an expertise in structural biology and has been overall well received.", event = "VCBM", booktitle = "Eurographics Workshop on Visual Computing for Biology and Medicine", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Waldin_Nicholas_2016_Chameleon/", } @inproceedings{Waldin_Nicholas_2016_Individualization, title = "Individualization of 2D Color Maps for People with Color Vision Deficiencies", author = "Nicholas Waldin and Matthias Bernhard and Peter Rautek and Ivan Viola", year = "2016", location = "Slomenice, Slovakia", booktitle = "Proceedings of the 32Nd Spring Conference on Computer Graphics", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Waldin_Nicholas_2016_Individualization/", } @article{Krone2016VABC, title = "Visual Analysis of Biomolecular Cavities: State of the Art", author = "Michael Krone and Barbora Kozlikova and Norbert Lindow and Marc Baaden and Daniel Baum and Julius Parulek and Hans-Christian Hege and Ivan Viola", year = "2016", abstract = "In this report we review and structure the branch of molecular visualization that is concerned with the visual analysis of cavities in macromolecular protein structures. First the necessary background, the domain terminology, and the goals of analytical reasoning are introduced. Based on a comprehensive collection of relevant research works, we present a novel classification for cavity detection approaches and structure them into four distinct classes: grid-based, Voronoi-based, surface-based, and probe-based methods. The subclasses are then formed by their combinations. We match these approaches with corresponding visualization technologies starting with direct 3D visualization, followed with non-spatial visualization techniques that for example abstract the interactions between structures into a relational graph, straighten the cavity of interest to see its profile in one view, or aggregate the time sequence into a single contour plot. We also discuss the current state of methods for the visual analysis of cavities in dynamic data such as molecular dynamics simulations. Finally, we give an overview of the most common tools that are actively developed and used in the structural biology and biochemistry research. Our report is concluded by an outlook on future challenges in the field.", journal = "Computer Graphics Forum", volume = "35", number = "3", pages = "527--551", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Krone2016VABC/", } @article{vad-2016-bre, title = "Generalized box-plot for root growth ensembles", author = "Viktor Vad and Douglas Cedrim and Wolfgang Busch and Peter Filzmoser and Ivan Viola", year = "2016", abstract = "Background In the field of root biology there has been a remarkable progress in root phenotyping, which is the efficient acquisition and quantitative description of root morphology. What is currently missing are means to efficiently explore, exchange and present the massive amount of acquired, and often time dependent root phenotypes. Results In this work, we present visual summaries of root ensembles by aggregating root images with identical genetic characteristics. We use the generalized box plot concept with a new formulation of data depth. In addition to spatial distributions, we created a visual representation to encode temporal distributions associated with the development of root individuals. Conclusions The new formulation of data depth allows for much faster implementation close to interactive frame rates. This allows us to present the statistics from bootstrapping that characterize the root sample set quality. As a positive side effect of the new data-depth formulation we are able to define the geometric median for the curve ensemble, which was well received by the domain experts.", journal = "BMC Bioinformatics", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/vad-2016-bre/", } @article{Cornel2016CFM, title = "Composite Flow Maps", author = "Daniel Cornel and Artem Konev and Berhard Sadransky and Zsolt Horvath and Andrea Brambilla and Ivan Viola and J\"{u}rgen Waser", year = "2016", abstract = "Flow maps are widely used to provide an overview of geospatial transportation data. Existing solutions lack the support for the interactive exploration of multiple flow components at once. Flow components are given by different materials being transported, different flow directions, or by the need for comparing alternative scenarios. In this paper, we combine flows as individual ribbons in one composite flow map. The presented approach can handle an arbitrary number of sources and sinks. To avoid visual clutter, we simplify our flow maps based on a force-driven algorithm, accounting for restrictions with respect to application semantics. The goal is to preserve important characteristics of the geospatial context. This feature also enables us to highlight relevant spatial information on top of the flow map such as traffic conditions or accessibility. The flow map is computed on the basis of flows between zones. We describe a method for auto-deriving zones from geospatial data according to application requirements. We demonstrate the method in real-world applications, including transportation logistics, evacuation procedures, and water simulation. Our results are evaluated with experts from corresponding fields.", journal = "Computer Graphics Forum", volume = "35", number = "3", pages = "461--470", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Cornel2016CFM/", } @habilthesis{viola-evr, title = "Effective Visual Representations", author = "Ivan Viola", year = "2016", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/viola-evr/", } @article{Waldin_Nicholas_2016_Colormaps, title = "Personalized 2D color maps", author = "Nicholas Waldin and Matthias Bernhard and Ivan Viola", year = "2016", abstract = "2D color maps are often used to visually encode complex data characteristics such as heat or height. The comprehension of color maps in visualization is affected by the display (e.g., a monitor) and the perceptual abilities of the viewer. In this paper we present a novel method to measure a user׳s ability to distinguish colors of a two-dimensional color map on a given monitor. We show how to adapt the color map to the user and display to optimally compensate for the measured deficiencies. Furthermore, we improve user acceptance of the calibration procedure by transforming the calibration into a game. The user has to sort colors along a line in a 3D color space in a competitive fashion. The errors the user makes in sorting these lines are used to adapt the color map to his perceptual capabilities.", issn = "0097-8493", journal = "Computers & Graphics", volume = "59", pages = "143--150", keywords = "Color; Perception, Perception, Color vision deficiency", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Waldin_Nicholas_2016_Colormaps/", } @article{lemuzic-mindek-2016-viseq, title = "Visibility Equalizer: Cutaway Visualization of Mesoscopic Biological Models", author = "Mathieu Le Muzic and Peter Mindek and Johannes Sorger and Ludovic Autin and David Goodsell and Ivan Viola", year = "2016", abstract = "In scientific illustrations and visualization, cutaway views are often employed as an effective technique for occlusion management in densely packed scenes.We propose a novel method for authoring cutaway illustrations of mesoscopic biological models. In contrast to the existing cutaway algorithms, we take advantage of the specific nature of the biological models. These models consist of thousands of instances with a comparably smaller number of different types. Our method constitutes a two stage process. In the first step, clipping objects are placed in the scene, creating a cutaway visualization of the model. During this process, a hierarchical list of stacked bars inform the user about the instance visibility distribution of each individual molecular type in the scene. In the second step, the visibility of each molecular type is fine-tuned through these bars, which at this point act as interactive visibility equalizers. An evaluation of our technique with domain experts confirmed that our equalizer-based approach for visibility specification is valuable and effective for both, scientific and educational purposes.", journal = "Computer Graphics Forum", volume = "35", number = "3", keywords = "molecular visualization, visibility, occlusion", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/lemuzic-mindek-2016-viseq/", } @inproceedings{Reisacher2016, title = "CellPathway: A Simulation Tool for Illustrative Visualization of Biochemical Networks", author = "Matthias Reisacher and Mathieu Le Muzic and Ivan Viola", year = "2016", abstract = "The molecular knowledge about complex biochemical reaction networks in biotechnology is crucial and has received a lot of attention lately. As a consequence, multiple visualization programs have been already developed to illustrate the anatomy of a cell. However, since a real cell performs millions of reactions every second to sustain live, it is necessary to move from anatomical to physiological illustrations to communicate knowledge about the behavior of a cell more accurately. In this thesis I propose a reaction system including a collision detection algorithm, which is able to work at the level of single atoms, to enable precise simulation of molecular interactions. To visually explain molecular activities during the simulation process, a real-time glow effect in combination with a clipping object have been implemented. Since intracellular processes are performed with a set of chemical transformations, a hierarchical structure is used to illustrate the impact of one reaction on the entire simulation. The CellPathway system integrates acceleration techniques to render large datasets containing millions of atoms in real-time, while the reaction system is processed directly on the GPU to enable simulation with more than 1000 molecules. Furthermore, a graphical user interface has been implemented to allow the user to control parameters during simulation interactively.", location = "Pilsen, Czech Republic", booktitle = "Proceedings of WSCG", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Reisacher2016/", } @article{Solteszova2016, title = "Output-Sensitive Filtering of Streaming Volume Data", author = "Veronika Solteszova and {\AA}smund Birkeland and Sergej Stoppel and Ivan Viola and Stefan Bruckner", year = "2016", abstract = "Real-time volume data acquisition poses substantial challenges for the traditional visualization pipeline where data enhancement is typically seen as a pre-processing step. In the case of 4D ultrasound data, for instance, costly processing operations to reduce noise and to remove artefacts need to be executed for every frame. To enable the use of high-quality filtering operations in such scenarios, we propose an output-sensitive approach to the visualization of streaming volume data. Our method evaluates the potential contribution of all voxels to the final image, allowing us to skip expensive processing operations that have little or no effect on the visualization. As filtering operations modify the data values which may affect the visibility, our main contribution is a fast scheme to predict their maximum effect on the final image. Our approach prioritizes filtering of voxels with high contribution to the final visualization based on a maximal permissible error per pixel. With zero permissible error, the optimized filtering will yield a result that is identical to filtering of the entire volume. We provide a thorough technical evaluation of the approach and demonstrate it on several typical scenarios that require on-the-fly processing.", journal = "Computer Graphics Forum", volume = "35", URL = "https://www.cg.tuwien.ac.at/research/publications/2016/Solteszova2016/", } @inproceedings{cellVIEW_2015, title = "cellVIEW: a Tool for Illustrative and Multi-Scale Rendering of Large Biomolecular Datasets", author = "Mathieu Le Muzic and Ludovic Autin and Julius Parulek and Ivan Viola", year = "2015", abstract = "In this article we introduce cellVIEW, a new system to interactively visualize large biomolecular datasets on the atomic level. Our tool is unique and has been specifically designed to match the ambitions of our domain experts to model and interactively visualize structures comprised of several billions atom. The cellVIEW system integrates acceleration techniques to allow for real-time graphics performance of 60 Hz display rate on datasets representing large viruses and bacterial organisms. Inspired by the work of scientific illustrators, we propose a level-of-detail scheme which purpose is two-fold: accelerating the rendering and reducing visual clutter. The main part of our datasets is made out of macromolecules, but it also comprises nucleic acids strands which are stored as sets of control points. For that specific case, we extend our rendering method to support the dynamic generation of DNA strands directly on the GPU. It is noteworthy that our tool has been directly implemented inside a game engine. We chose to rely on a third party engine to reduce software development work-load and to make bleeding-edge graphics techniques more accessible to the end-users. To our knowledge cellVIEW is the only suitable solution for interactive visualization of large bimolecular landscapes on the atomic level and is freely available to use and extend.", month = sep, isbn = "978-3-905674-82-8", publisher = "The Eurographics Association", organization = "EG Digital Library", location = "Chester, United Kingdom", issn = "2070-5786", editor = "Katja B\"{u}hler and Lars Linsen and Nigel W. John", booktitle = "Eurographics Workshop on Visual Computing for Biology and Medicine", pages = "61--70", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/cellVIEW_2015/", } @article{Viola_Ivan_2015_MCT, title = "MoleCollar and Tunnel Heat Map Visualizations for Conveying Spatio-Temporo-Chemical Properties Across and Along Protein Voids", author = "Jan Byska and Adam Jurcik and Eduard Gr\"{o}ller and Ivan Viola and Barbora Kozlikova", year = "2015", abstract = "Studying the characteristics of proteins and their inner void space, including their geometry, physico-chemical properties and dynamics are instrumental for evaluating the reactivity of the protein with other small molecules. The analysis of long simulations of molecular dynamics produces a large number of voids which have to be further explored and evaluated. In this paper we propose three new methods: two of them convey important properties along the long axis of a selected void during molecular dynamics and one provides a comprehensive picture across the void. The first two proposed methods use a specific heat map to present two types of information: an overview of all detected tunnels in the dynamics and their bottleneck width and stability over time, and an overview of a specific tunnel in the dynamics showing the bottleneck position and changes of the tunnel length over time. These methods help to select a small subset of tunnels, which are explored individually and in detail. For this stage we propose the third method, which shows in one static image the temporal evolvement of the shape of the most critical tunnel part, i.e., its bottleneck. This view is enriched with abstract depictions of different physicochemical properties of the amino acids surrounding the bottleneck. The usefulness of our newly proposed methods is demonstrated on a case study and the feedback from the domain experts is included. The biochemists confirmed that our novel methods help to convey the information about the appearance and properties of tunnels in a very intuitive and comprehensible manner.", month = may, journal = "Computer Graphics Forum", volume = "3", number = "34", note = "EuroVis 2015 - Conference Proceedings", pages = "1--10", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/Viola_Ivan_2015_MCT/", } @inproceedings{Viola_Ivan_2015_VBS, title = "Visualization of Biomolecular Structures: State of the Art", author = "Barbora Kozlikova and Michael Krone and Norbert Lindow and Martin Falk and Marc Baaden and Daniel Baum and Ivan Viola and Julius Parulek and Hans-Christian Hege", year = "2015", abstract = "Structural properties of molecules are of primary concern in many fields. This report provides a comprehensive overview on techniques that have been developed in the fields of molecular graphics and visualization with a focus on applications in structural biology. The field heavily relies on computerized geometric and visual representations of three-dimensional, complex, large, and time-varying molecular structures. The report presents a taxonomy that demonstrates which areas of molecular visualization have already been extensively investigated and where the field is currently heading. It discusses visualizations for molecular structures, strategies for efficient display regarding image quality and frame rate, covers different aspects of level of detail, and reviews visualizations illustrating the dynamic aspects of molecular simulation data. The report concludes with an outlook on promising and important research topics to enable further success in advancing the knowledge about interaction of molecular structures.", month = may, publisher = "The Eurographics Association", location = "Cagliari, Italy", event = "Eurographics Conference on Visualization (EuroVis) (2015)", editor = "R. Borgo and F. Ganovelli and I. Viola", booktitle = "Eurographics Conference on Visualization (EuroVis) - STARs", pages = "061--081", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/Viola_Ivan_2015_VBS/", } @inproceedings{mindek-2015-mc, title = "Automatized Summarization of Multiplayer Games", author = "Peter Mindek and Ladislav \v{C}mol\'{i}k and Ivan Viola and Eduard Gr\"{o}ller and Stefan Bruckner", year = "2015", abstract = "We present a novel method for creating automatized gameplay dramatization of multiplayer video games. The dramatization serves as a visual form of guidance through dynamic 3D scenes with multiple foci, typical for such games. Our goal is to convey interesting aspects of the gameplay by animated sequences creating a summary of events which occurred during the game. Our technique is based on processing many cameras, which we refer to as a flock of cameras, and events captured during the gameplay, which we organize into a so-called event graph. Each camera has a lifespan with a certain time interval and its parameters such as position or look-up vector are changing over time. Additionally, during its lifespan each camera is assigned an importance function, which is dependent on the significance of the structures that are being captured by the camera. The images captured by the cameras are composed into a single continuous video using a set of operators based on cinematographic effects. The sequence of operators is selected by traversing the event graph and looking for specific patterns corresponding to the respective operators. In this way, a large number of cameras can be processed to generate an informative visual story presenting the gameplay. Our compositing approach supports insets of camera views to account for several important cameras simultaneously. Additionally, we create seamless transitions between individual selected camera views in order to preserve temporal continuity, which helps the user to follow the virtual story of the gameplay.", month = apr, isbn = "978-80-223-3844-8", publisher = "Comenius University, Bratislava", location = "Smolenice, Slovakia", editor = "Joaquim Jorge, Luis Paulo Santos, Roman Durikovic", booktitle = "Proceedings of Spring Conference on Computer Graphics 2015", pages = "93--100", keywords = "storytelling, game visualization, animation", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/mindek-2015-mc/", } @inproceedings{lemuzic_2015_timelapse, title = "Illustrative Timelapse: A Technique for Illustrative Visualization of Particle Simulations on the Mesoscale Level", author = "Mathieu Le Muzic and Manuela Waldner and Julius Parulek and Ivan Viola", year = "2015", abstract = "Animated movies are a popular way to communicate complex phenomena in cell biology to the broad audience. Animation artists apply sophisticated illustration techniques to communicate a story, while trying to maintain a realistic representation of a complex dynamic environment. Since such hand-crafted animations are timeconsuming and cost-intensive to create, our goal is to formalize illustration techniques used by artists to facilitate the automatic creation of visualizations generated from mesoscale particle-based molecular simulations. Our technique Illustrative Timelapse supports visual exploration of complex biochemical processes in dynamic environments by (1) seamless temporal zooming to observe phenomena in different temporal resolutions, (2) visual abstraction of molecular trajectories to ensure that observers are able to visually follow the main actors, (3) increased visual focus on events of interest, and (4) lens effects to preserve a realistic representation of the environment in the context. Results from a first user study indicate that visual abstraction of trajectories improves the ability to follow a story and is also appreciated by users. Lens effects increased the perceived amount of molecular motion in the environment while trading off traceability of individual molecules.", month = apr, publisher = "IEEE", organization = "8th IEEE Pacific Visualization Symposium (PacificVis 2015)", location = "Zijingang Campus, Zhejiang University, Hangzhou, China", booktitle = "Visualization Symposium (PacificVis), 2015 IEEE Pacific", pages = "247--254", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/lemuzic_2015_timelapse/", } @article{waldner-2014-af, title = " Attractive Flicker: Guiding Attention in Dynamic Narrative Visualizations", author = "Manuela Waldner and Mathieu Le Muzic and Matthias Bernhard and Werner Purgathofer and Ivan Viola", year = "2014", abstract = "Focus+context techniques provide visual guidance in visualizations by giving strong visual prominence to elements of interest while the context is suppressed. However, finding a visual feature to enhance for the focus to pop out from its context in a large dynamic scene, while leading to minimal visual deformation and subjective disturbance, is challenging. This paper proposes Attractive Flicker, a novel technique for visual guidance in dynamic narrative visualizations. We first show that flicker is a strong visual attractor in the entire visual field, without distorting, suppressing, or adding any scene elements. The novel aspect of our Attractive Flicker technique is that it consists of two signal stages: The first “orientation stage” is a short but intensive flicker stimulus to attract the attention to elements of interest. Subsequently, the intensive flicker is reduced to a minimally disturbing luminance oscillation (“engagement stage”) as visual support to keep track of the focus elements. To find a good trade-off between attraction effectiveness and subjective annoyance caused by flicker, we conducted two perceptual studies to find suitable signal parameters. We showcase Attractive Flicker with the parameters obtained from the perceptual statistics in a study of molecular interactions. With Attractive Flicker, users were able to easily follow the narrative of the visualization on a large display, while the flickering of focus elements was not disturbing when observing the context.", month = dec, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "20", number = "12", pages = "2456--2465", keywords = "Narrative Visualization, Flicker, Visual Attention", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/waldner-2014-af/", } @article{birkeland_aasmund_2014_pums, title = "Perceptually Uniform Motion Space", author = "{\AA}smund Birkeland and Cagatay Turkay and Ivan Viola", year = "2014", abstract = "Flow data is often visualized by animated particles inserted into a ?ow ?eld. The velocity of a particle on the screen is typically linearly scaled by the velocities in the data. However, the perception of velocity magnitude in animated particles is not necessarily linear. We present a study on how different parameters affect relative motion perception. We have investigated the impact of four parameters. The parameters consist of speed multiplier, direction, contrast type and the global velocity scale. In addition, we investigated if multiple motion cues, and point distribution, affect the speed estimation. Several studies were executed to investigate the impact of each parameter. In the initial results, we noticed trends in scale and multiplier. Using the trends for the signi?cant parameters, we designed a compensation model, which adjusts the particle speed to compensate for the effect of the parameters. We then performed a second study to investigate the performance of the compensation model. From the second study we detected a constant estimation error, which we adjusted for in the last study. In addition, we connect our work to established theories in psychophysics by comparing our model to a model based on Stevens’ Power Law.", month = nov, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "20", number = "11", issn = "1077-2626", pages = "1542--1554", keywords = "motion visualization, motion perception, animation, evauation, perceptual model", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/birkeland_aasmund_2014_pums/", } @article{Viola_Ivan_IIP, title = "Interactively illustrating polymerization using three-level model fusion", author = "Ivan Koles\'{a}r and Julius Parulek and Ivan Viola and Stefan Bruckner and Anne-Kristin Stavrum and Helwig Hauser", year = "2014", abstract = "Background: Research in cell biology is steadily contributing new knowledge about many aspects of physiological processes, both with respect to the involved molecular structures as well as their related function. llustrations of the spatio-temporal development of such processes are not only used in biomedical education, but also can serve scientists as an additional platform for in-silico experiments. Results: In this paper, we contribute a new, three-level modeling approach to illustrate physiological processes from the class of polymerization at different time scales. We integrate physical and empirical modeling, according to which approach best suits the different involved levels of detail, and we additionally enable a form of interactive steering, while the process is illustrated. We demonstrate the suitability of our approach in the context of several polymerization processes and report from a first evaluation with domain experts. Conclusion: We conclude that our approach provides a new, hybrid modeling approach for illustrating the process of emergence in physiology, embedded in a densely filled environment. Our approach of a complementary fusion of three systems combines the strong points from the different modeling approaches and is capable to bridge different spatial and temporal scales.", month = oct, issn = "1471-2105", journal = "BMC Bioinformatics 2014", number = "345", volume = "15", pages = "1--16", keywords = "Multi-agent modeling, L-system modeling, Biochemical visualization, Visualization of physiology, Polymerization", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Viola_Ivan_IIP/", } @inproceedings{waldner-2014-ghi, title = "Graphical Histories of Information Foraging", author = "Manuela Waldner and Stefan Bruckner and Ivan Viola", year = "2014", abstract = "During information foraging, knowledge workers iteratively seek, filter, read, and extract information. When using multiple information sources and different applications for information processing, re-examination of activities for validation of previous decisions or re-discovery of previously used information sources is challenging. In this paper, we present a novel representation of cross-application histories to support recall of past operations and re-discovery of information resources. Our graphical history consists of a cross-scale visualization combining an overview node-link diagram of used desktop resources with nested (animated) snapshot sequences, based on a recording of the visual screen output during the users’ desktop work. This representation makes key elements of the users’ tasks visually stand out, while exploiting the power of visual memory to recover subtle details of their activities. In a preliminary study, users found our graphical history helpful to recall details of an information foraging task and commented positively on the ability to expand overview nodes into snapshot and video sequences.", month = oct, isbn = "978-1-4503-2542-4", publisher = "ACM", organization = "NordiCHI’14 - Nordic Conference on Human-Computer Interaction", location = "Helsinki, Finland", booktitle = "Proceedings of the 8th Nordic Conference on Human-Computer Interaction: Fun, Fast, Foundational ", pages = "295--304", keywords = "Graph visualization, Interaction history, Provenance", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/waldner-2014-ghi/", } @inproceedings{Viola_Ivan_VDP, title = "Visibility-Driven Processing of Streaming Volume Data", author = "Veronika Solteszova and {\AA}smund Birkeland and Ivan Viola and Stefan Bruckner", year = "2014", abstract = "In real-time volume data acquisition, such as 4D ultrasound, the raw data is challenging to visualize directly without additional processing. Noise removal and feature detection are common operations, but many methods are too costly to compute over the whole volume when dealing with live streamed data. In this paper, we propose a visibility-driven processing scheme for handling costly on-the-fly processing of volumetric data in real-time. In contrast to the traditional visualization pipeline, our scheme utilizes a fast computation of the potentially visible subset of voxels which significantly reduces the amount of data required to process. As filtering operations modify the data values which may affect their visibility, our method for visibility-mask generation ensures that the set of elements deemed visible does not change after processing. Our approach also exploits the visibility information for the storage of intermediate values when multiple operations are performed in sequence, and can therefore significantly reduce the memory overhead of longer filter pipelines. We provide a thorough technical evaluation of the approach and demonstrate it on several typical scenarios where on-the-fly processing is required.", month = sep, isbn = "978-3-905674-62-0", publisher = "Eurographics Association", location = "Vienna, Austria", issn = "2070-5778", event = "4th EG Workshop on Visual Computing and Biology Medicine", editor = "Ivan Viola and Katja Buehler and Timo Ropinski", booktitle = "Proceedings of EG VCBM 2014", pages = "127--136", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Viola_Ivan_VDP/", } @inproceedings{Viola_Ivan_DAC, title = "Deriving Anatomical Context from 4D Ultrasound", author = "Markus M\"{u}ller and Linn E. S. Helljesen and Raphael Prevost and Ivan Viola and Kim Nylund and Odd Helge Gilja and Nassir Navab and Wolfgang Wein", year = "2014", abstract = "Real-time three-dimensional (also known as 4D) ultrasound imaging using matrix array probes has the potential to create large-volume information of entire organs such as the liver without external tracking hardware. This information can in turn be placed into the context of a CT or MRI scan of the same patient. However for such an approach many image processing challenges need to be overcome and sources of error addressed, including reconstruction drift, anatomical deformations, varying appearance of anatomy, and imaging artifacts. In this work,we present a fully automatic system including robust image-based ultrasound tracking, a novel learning-based global initialization of the anatomical context, and joint mono- and multi-modal registration. In an evaluation on 4D US sequences and MRI scans of eight volunteers we achieve automatic reconstruction and registration without any user interaction, assess the registration errors based on physician-defined landmarks, and demonstrate realtime tracking of free-breathing sequences.", month = sep, isbn = "978-3-905674-62-0", publisher = "Eurographics Association", note = "The electronic version of the proceedings is available from the Eurographics Digital Library at http://diglib.eg.org", location = "Vienna, Austria", issn = "2070-5778", event = "4th Eurographics Workshop on Visual Computing for Biology and Medicine", editor = "Ivan Viola and Katja Buehler and Timo Ropinski", booktitle = "Proceedings of EG VCBM14", pages = "173--180", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Viola_Ivan_DAC/", } @incollection{Viola_Ivan_UVP, title = "The Ultrasound Visualization Pipeline", author = "{\AA}smund Birkeland and Veronika Solteszova and Dieter H\"{o}nigmann and Odd Helge Gilja and Svein Brekke and Timo Ropinski and Ivan Viola", year = "2014", abstract = "Radiology is one of the main tools in modern medicine. A numerous set of deceases, ailments and treatments utilize accurate images of the patient. Ultrasound is one of the most frequently used imaging modality in medicine. The high spatial resolution, its interactive nature and non-invasiveness makes it the first choice in many examinations. Image interpretation is one of ultrasound’s main challenges. Much training is required to obtain a confident skill level in ultrasound-based diagnostics. State-of-the-art graphics techniques is needed to provide meaningful visualizations of ultrasound in real-time. In this paper we present the process-pipeline for ultrasound visualization, including an overview of the tasks performed in the specific steps. To provide an insight into the trends of ultrasound visualization research, we have selected a set of significant publications and divided them into a technique-based taxonomy covering the topics pre-processing, segmentation, registration, rendering and augmented reality. For the different technique types we discuss the difference between ultrasound-based techniques and techniques for other modalities.", month = sep, address = "http://link.springer.com/chapter/10.1007%2F978-1-4471-6497-5_24", booktitle = "Scientific Visualization", chapter = "Uncertainty, Multifield, Biomedical, and Scalable Visualization", editor = "Charles D. Hansen, Min Chen, Christopher R. Johnson, Arie E. Kaufman, Hans Hagen", isbn = "978-1-4471-6496-8", publisher = "Springer London", series = "Mathematics and Visualization", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Viola_Ivan_UVP/", } @inproceedings{kolesar-ivan-2014-polymers, title = "Illustrating Polymerization using Three-level Model Fusion", author = "Ivan Koles\'{a}r and Julius Parulek and Ivan Viola and Stefan Bruckner and Anne-Kristin Stavrum and Helwig Hauser", year = "2014", abstract = "Research in cell biology is steadily contributing new knowledge about many di?erent aspects of physiological processes like polymerization, both with respect to the involved molecular structures as well as their related function. Illustrations of the spatio-temporal development of such processes are not only used in biomedical education, but also can serve scientists as an additional platform for in-silico experiments. In this paper, we contribute a new, three-level modeling approach to illustrate physiological processes from the class of polymerization at di?erent time scales. We integrate physical and empirical modeling, according to which approach suits the di?erent involved levels of detail best, and we additionally enable a simple form of interactive steering while the process is illustrated. We demonstrate the suitability of our approach in the context of several polymerization processes and report from a ?rst evaluation with domain experts.", month = jul, publisher = "IEEE Digital Library", organization = "4th Symposium on Biological Data Visualization (in Conjunction with the International Conference on Intelligent Systems for Molecular Biology (ISMB 2014)) ", location = "Boston, USA", booktitle = "Proceedings of IEEE BioVis 2014", pages = "1--22", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/kolesar-ivan-2014-polymers/", } @article{lemuzic-2014-ivm, title = "Illustrative Visualization of Molecular Reactions using Omniscient Intelligence and Passive Agents ", author = "Mathieu Le Muzic and Julius Parulek and Anne-Kristin Stavrum and Ivan Viola", year = "2014", abstract = "In this paper we propose a new type of a particle systems, tailored for illustrative visualization purposes, in particular for visualizing molecular reactions in biological networks. Previous visualizations of biochemical processes were exploiting the results of agent-based modeling. Such modeling aims at reproducing accurately the stochastic nature of molecular interactions. However, it is impossible to expect events of interest happening at a certain time and location, which is impractical for storytelling. To obtain the means of controlling molecular interactions, we propose to govern passive agents with an omniscient intelligence, instead of giving to the agents the freedom of initiating reaction autonomously. This makes it possible to generate illustrative animated stories that communicate the functioning of the molecular machinery. The rendering performance delivers for interactive framerates of massive amounts of data, based on the dynamic tessellation capabilities of modern graphics cards. Finally, we report an informal expert feedback we obtained from the potential users.", month = jun, journal = "Computer Graphics Forum", volume = "33", number = "3", note = "Article first published online: 12 JUL 2014", pages = "141--150", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/lemuzic-2014-ivm/", } @article{Viola_Ivan_CLD, title = "Continuous Levels-of-Detail and Visual Abstraction for Seamless Molecular Visualization", author = "Julius Parulek and Daniel J\"{o}nsson and Timo Ropinski and Stefan Bruckner and Anders Ynnerman and Ivan Viola", year = "2014", abstract = "Molecular visualization is often challenged with rendering of large molecular structures in real time. We introduce a novel approach that enables us to show even large protein complexes. Our method is based on the level-of-detail concept, where we exploit three different abstractions combined in one visualization. Firstly, molecular surface abstraction exploits three different surfaces, solvent-excluded surface (SES), Gaussian kernels and van der Waals spheres, combined as one surface by linear interpolation. Secondly, we introduce three shading abstraction levels and a method for creating seamless transitions between these representations. The SES representation with full shading and added contours stands in focus while on the other side a sphere representation of a cluster of atoms with constant shading and without contours provide the context. Thirdly, we propose a hierarchical abstraction based on a set of clusters formed on molecular atoms. All three abstraction models are driven by one importance function classifying the scene into the near-, mid- and far-field. Moreover, we introduce a methodology to render the entire molecule directly using the A-buffer technique, which further improves the performance. The rendering performance is evaluated on series of molecules of varying atom counts.", month = may, issn = "0167-7055", journal = "Computer Graphics Forum", number = "6", volume = "33", pages = "276--287", keywords = "clustering, implicit surfaces, level of detail algorithms, scientific visualization, Computer Applications", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Viola_Ivan_CLD/", } @misc{lemuzic_2014_ipv, title = "Illustrative Visualization of Biochemical Processes Featuring Multiple Temporal Scales", author = "Mathieu Le Muzic and Julius Parulek and Manuela Waldner and Ivan Viola", year = "2014", abstract = "Scientific illustrators are commonly using structural description of molecular compounds when depicting complex biochemical processes. However, computational biology also provides procedural models describing the function of biological processes which are not currently used in the production pipeline. Instead, animators utilize scientific knowledge to manually animate and reproduce the functioning of cellular biology. We would like to explore the use of such models in order to generate explanatory illustrations that would show how molecular machinery works. Particle-based simulations provide the means for spatially representing the dynamics of biochemical processes. They compute the positions of each single particle and are supposed to mimic a realistic behaviour of the metabolites. Current mesoscale visualization also allows to directly show the results of such simulations by mapping the positions of particles in a virtual 3D environment. Nevertheless, some biochemical processes, like the DNA repair for instance, exhibit temporal multiscale aspects because they comprise diffusion rates which are much greater in comparison with reaction rates. As a result, it is challenging to produce a clear and coherent visualization out of this type of simulation. Indeed, when viewing the process at the pace which would let us see the reactions, it becomes impossible for the human eye to keep track of individual elements because of the very large diffusion displacements. On the other hand, if one would playback the simulation slow enough to be see a steady motion of individual elements, then only a very few number of reactions would occur in a reasonable amount of time. In this work we propose to solve the problem associated with multiple temporal scales by providing means for spatial. With this approach we aim at showing the two different temporal scale at the same time by using advanced trajectory smoothing mechanism. This would allow us to see individual elements while showing a world full of reactions, hence enabling us to communicate complex biological processes and molecular machineries in a comprehensive way. ", event = "Eurographics Workshop on Visual Computing for Biology", Conference date = "Poster presented at Eurographics Workshop on Visual Computing for Biology (2014-09-04--2014-09-05)", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/lemuzic_2014_ipv/", } @article{Viola_Ivan_2013_VCA, title = "Visual cavity analysis in molecular simulations", author = "Julius Parulek and Cagatay Turkay and Nathalie Reuter and Ivan Viola", year = "2013", abstract = "Molecular surfaces provide a useful mean for analyzing interactions between biomolecules; such as identification and characterization of ligand binding sites to a host macromolecule. We present a novel technique, which extracts potential binding sites, represented by cavities, and characterize them by 3D graphs and by amino acids. The binding sites are extracted using an implicit function sampling and graph algorithms. We propose an advanced cavity exploration technique based on the graph parameters and associated amino acids. Additionally, we interactively visualize the graphs in the context of the molecular surface. We apply our method to the analysis of MD simulations of Proteinase 3, where we verify the previously described cavities and suggest a new potential cavity to be studied.", month = nov, issn = "1471-2105", journal = "BMC Bioinformatics", number = "Suppl 19:S4 ", volume = "14", pages = "1--15", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_VCA/", } @misc{Viola_2013_IDV, title = "Importance Driven Visualization of Molecular Surfaces", author = "Julius Parulek and Timo Ropinski and Ivan Viola", year = "2013", abstract = "We present a novel rendering method, based on the level-of-detail concept, which shows protein complexes over time in real-time. We exploit three different molecular surface models, solvent excluded surface (SES), Gaussian kernels and van der Waals spheres combined in one seamless visualization. As a general rule, closest to the viewer we aim at providing a maximum of relevant information related to the structure and binding sites. Such information is conveyed by the SES representation. Farther away from the viewer, we are smoothly changing the visual representation to an approximation of SES through Gaussian kernels. The least detailed representation is based on simple sphere splatting and is dedicated to structures farthest away from the viewer. A more general solution leads us to the definition of a 3D importance function that is based on the distance measure from a molecular feature. In order to preserve smoothness in transition areas, we introduce three shading levels that correspond to their geometric counterparts and a method for creating seamless transition between these representations. The SES representation with full shading and added contours stands in focus while on the other side a sphere representation with constant shading and without contours provide the context. Moreover, we introduce a methodology to render the entire molecule directly using the A-buffer technique, which further improves the performance. The rendering performance is evaluated on series of molecules of varying atom counts.", month = oct, publisher = "BioVis website (http://www.biovis.net/year/2013/posters)", location = "Atlanta, GA", event = "3rd IEEE Symposium on Biological Data Visualization", Conference date = "Poster presented at 3rd IEEE Symposium on Biological Data Visualization (2013-10-13--2013-10-14)", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_2013_IDV/", } @article{Viola_Ivan_2013_GS, title = "Geological storytelling", author = "Endre M. Lidal and Mattia Natali and Daniel Patel and Helwig Hauser and Ivan Viola", year = "2013", abstract = "Developing structural geological models from exploratory subsea imaging is difficult and an ill-posed process. The structural geological processes that take place in the subsurface are both complex and time-dependent. We present Geological Storytelling, a novel graphical system for performing rapid and expressive geomodeling. Geologists can convey geological stories that externalize both their model and the reasoning process behind it through our simple, yet expressive sketch-based, flip-over canvases. This rapid modeling interface makes it easy to construct a large variety of geological stories, and our story tree concept facilitates easy management and the exploration of these alternatives. The stories are then animated and the geologists can examine and compare them to identify the most plausible models. Finally, the geological stories can be presented as illustrative animations of automatically synthesized 3D models, which efficiently communicate the complex geological evolution to non-experts and decision makers. Geological storytelling provides a complete pipeline from the ideas and knowledge in the mind of the geologist, through externalized artifacts specialized for discussion and knowledge dissemination among peer-experts, to automatically rendered illustrative 3D animations for communication to lay audience. We have developed geological storytelling in collaboration with domain experts that work with the modeling challenges on a daily basis. For evaluation, we have developed a geological storytelling prototype and presented it to experts and academics from the geosciences. In their feedback, they acknowledge that the rapid and expressive sketching of stories can make them explore more alternatives and that the 3D illustrative animations assist in communicating their models.", month = aug, issn = "0097-8493", journal = "Computer & Graphics", number = "5", volume = "37", pages = "445--459", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_GS/", } @inproceedings{Viola_Ivan_2013_RSb, title = "Rapid Sketch-based 3D Modeling of Geology", author = "Endre M. Lidal and Morten Bendiksen and Daniel Patel and Ivan Viola", year = "2013", abstract = "We present and compare two different approaches for performing rapid 3D geological modeling. The ad-hoc approach is based on a composition of many specialized modeling functions, while the generic approach provides one powerful, generic modeling function. Our experiences after developing these two approaches are that the solution space of 3D geological modeling is more extensive than we initially expected and most likely larger than for other modeling domains such as architecture. Further, more research is needed to investigate whether it is possible to find one well defined toolset of sketching metaphors that is able to cover all of geological modeling.", month = jun, publisher = "Springer", organization = "Euro Vis 2013", note = "Workshop on Visualisation in Environmental Sciences (EnvirVis) (2013)", location = "Leipzig, Germany", booktitle = "Proceedings of EnvirVis Short Papers 2013, 2013", pages = "1--5", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_RSb/", } @article{Viola_Ivan_2013_RMA, title = "Rule-based method for automatic scaffold assembly from 3D building models", author = "Tyge Løvset and Dag Magne Ulvang and Tor Christian Bekkvik and K{\aa}re Villanger and Ivan Viola", year = "2013", abstract = "To manually specify an optimal scaffold assembly for a given building geometry is a time consuming task. Our goal is to automate the process of selecting and placing scaffold components in order to design an optimal scaffold assembly for a specific building. The resulting assembly must be possible to construct in practice, should be practical to use for the workers, must satisfy governmental rules and regulations and should ideally result in minimum accumulated component cost. We propose a novel procedural modeling pipeline based on an input house model. First we extract vital coordinates from the house model that define the 3D scaffold placement. These coordinates are the basis for defining the positioning of scaffold cells. In the next step we populate the cells with actual scaffold components geometry. The resulting model is visualized to assist the assembly process. Additionally it is decomposed into elementary building blocks to produce assembly component lists to estimate the scaffold cost estimates, compute the weight for transportation and packing of components from a warehouse. The result from the automated process is compared to scaffold design produced manually by a professional scaffold designer.", month = jun, issn = "0097-8493", journal = "Computer & Graphics", number = "4", volume = "37", pages = "256--268", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_RMA/", } @inproceedings{Viola_Ivan_2013_HQ3, title = "High-Quality 3D Visualization of In-Situ Ultrasonography", author = "Ivan Viola and {\AA}smund Birkeland and Veronika Solteszova and Linn Helljesen and Helwig Hauser and Spiros Kotopoulis and Kim Nylund and Dag Magne Ulvang and Ola Kristoffer Øye and Trygve Hausken and Odd Helge Gilja", year = "2013", abstract = "In recent years medical ultrasound has experienced a rapid development in the quality of real-time 3D ultrasound (US) imaging. The image quality of the 3D volume that was previously possible to achieve within the range of a few seconds, is now possible in a fraction of a second. This technological advance offers entirely new opportunities for the use of US in the clinic. In our project, we investigate how real-time 3D US can be combined with high-performance processing of today’s graphics hardware to allow for high-quality 3D visualization and precise navigation during the examination.", month = may, publisher = "Eurogrpahics", note = "1st Prize - Medical Prize Short Paper", location = "Girona, Spain", booktitle = "EG 2013 - Dirk Bartz Prize", pages = "1--4", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_HQ3/", } @inproceedings{Viola_Ivan_2013_D3D, title = "Doppler-based 3D Blood Flow Imaging and Visualization", author = "{\AA}smund Birkeland and Dag Magne Ulvang and Kim Nylund and Trygve Hausken and Odd Helge Gilja and Ivan Viola", year = "2013", abstract = "Blood flow is a very important part of human physiology. In this paper, we present a new method for estimating and visualizing 3D blood flow on-the-fly based on Doppler ultrasound. We add semantic information about the geometry of the blood vessels in order to recreate the actual velocities of the blood. Assuming a laminar flow, the flow direction is related to the general direction of the vessel. Based on the center line of the vessel, we create a vector field representing the direction of the vessel at any given point. The actual flow velocity is then estimated from the Doppler ultrasound signal by back-projecting the velocity in the measured direction, onto the vessel direction. Additionally, we estimate the flux at user-selected cross-sections of the vessel by integrating the velocities over the area of the cross-section. In order to visualize the flow and the flux, we propose a visualization design based on traced particles colored by the flux. The velocities are visualized by animating particles in the flow field. Further, we propose a novel particle velocity legend as a means for the user to estimate the numerical value of the current velocity. Finally, we perform an evaluation of the technique where the accuracy of the velocity estimation is measured using a 4D MRI dataset as a basis for the ground truth.", month = may, isbn = "978-80-223-3377-1", publisher = "ACM Publishing House", location = "Smolenice, Slovak Republic", booktitle = "SCCG 2013 - 29th Proceedings Spring conference on Computer Graphics", pages = "128--135", keywords = "Medical Visualization, Biomedical", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_D3D/", } @inproceedings{Viola_Ivan_2013_SVA, title = "Seamless Visual Abstraction of Molecular Surfaces", author = "Julius Parulek and Timo Ropinski and Ivan Viola", year = "2013", abstract = "Molecular visualization is often challenged with rendering of large sequences of molecular simulations in real time. We introduce a novel approach that enables us to show even large protein complexes over time in real-time. Our method is based on the level-ofdetail concept, where we exploit three different molecular surface models, solvent excluded surface (SES), Gaussian kernels and van der Waals spheres combined in one visualization. We introduce three shading levels that correspond to their geometric counterparts and a method for creating seamless transition between these representations. The SES representation with full shading and added contours stands in focus while on the other side a sphere representation with constant shading and without contours provide the context. Moreover, we introduce a methodology to render the entire molecule directly using the A-buffer technique, which further improves the performance. The rendering performance is evaluated on series of molecules of varying atom counts.", month = may, isbn = "978-80-223-3377-1", series = " SCCG '13", publisher = "ACM Publishing House", organization = "Comenius University, Bratislava", location = "Smolenice, Slovak Republic", editor = "Roman Durikovi\v{c}, Holly Rushmeier", booktitle = "SCCG 2013 - 29th Proceedings Spring conference on Computer Graphics", pages = "120--127", keywords = "Implicit Surfaces, Level-of-detail, Visualization of Molecular Surfaces", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_SVA/", } @inproceedings{2013_Viola_Ivan_2013_MTS, title = "Modeling Terrains and Subsurface Geology", author = "Mattia Natali and Endre M. Lidal and Julius Parulek and Ivan Viola and Daniel Patel", year = "2013", abstract = "The process of creating terrain and landscape models is important in a variety of computer graphics and visualization applications, from films and computer games, via flight simulators and landscape planning, to scientific visualization and subsurface modelling. Interestingly, the modelling techniques used in this large range of application areas have started to meet in the last years. In this state-of-the-art report, we present two taxonomies of different modelling methods. Firstly we present a data oriented taxonomy, where we divide modelling into three different scenarios: the data-free, the sparse-data and the dense-data scenario. Then we present a workflow oriented taxonomy, where we divide modelling into the separate stages necessary for creating a geological model. We start the report by showing that the new trends in geological modelling are approaching the modelling methods that have been developed in computer graphics. We then give an introduction to the process of geological modelling followed by our two taxonomies with descriptions and comparisons of selected methods. Finally we discuss the challenges and trends in geological modelling.", month = may, publisher = "Eurographics 2013 - State of the Art Reports", organization = "Eurographics", location = "Girona, Spain", booktitle = "INPROCEEDINGS, EuroGraphics 2013 State of the Art Reports (STARs), 2013", pages = "155--173", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/2013_Viola_Ivan_2013_MTS/", } @article{Viola_Ivan_2013_CAI, title = "Computer-aided image geometry analysis and subset selection for optimizing texture quality in photorealistic models", author = "Aleksandra Anna Sima and Xavier Bonaventura and Miquel Feixas and Mateu Sbert and John Anthony Howell and Ivan Viola and Simon John Buckley", year = "2013", abstract = "Photorealistic 3D models are used for visualization, interpretation and spatial measurement in many disciplines, such as cultural heritage, archaeology and geoscience. Using modern image- and laser-based 3D modelling techniques, it is normal to acquire more data than is finally used for 3D model texturing, as images may be acquired from multiple positions, with large overlap, or with different cameras and lenses. Such redundant image sets require sorting to restrict the number of images, increasing the processing efficiency and realism of models. However, selection of image subsets optimized for texturing purposes is an example of complex spatial analysis. Manual selection may be challenging and time-consuming, especially for models of rugose topography, where the user must account for occlusions and ensure coverage of all relevant model triangles. To address this, this paper presents a framework for computer-aided image geometry analysis and subset selection for optimizing texture quality in photorealistic models. The framework was created to offer algorithms for candidate image subset selection, whilst supporting refinement of subsets in an intuitive and visual manner. Automatic image sorting was implemented using algorithms originating in computer science and information theory, and variants of these were compared using multiple 3D models and covering image sets, collected for geological applications. The image subsets provided by the automatic procedures were compared to manually selected sets and their suitability for 3D model texturing was assessed. Results indicate that the automatic sorting algorithms are a promising alternative to manual methods. An algorithm based on a greedy solution to the weighted set-cover problem provided image sets closest to the quality and size of the manually selected sets. The improved automation and more reliable quality indicators make the photorealistic model creation workflow more accessible for application experts, increasing the user’s confidence in the final textured model completeness.", month = mar, journal = "Computers & Geosciences", volume = "52", pages = "281--291", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_CAI/", } @talk{Viola_Ivan_2013_DC, title = "Declarative Visualization", author = "Ivan Viola", year = "2013", abstract = "Visualization algorithms are nowadays formalized in an imperative manner, i.e. the algorithm is explicitly executed on input data and dictates a determined visualization outcome. The efficiency of such an algorithm is measured by means of the computational performance, data-scalability and user studies. In my talk I will speculate on a novel theoretical concept for the development of new visualization methodology that becomes ultimately declarative and algorithm-free, by moving the user study from a validation stage into the center of the iterative design stage. Initial visualization from input data is considered as the first design draft, which will undergo several revisions. This draft can be achieved by executing a traditional imperative algorithm or it can even be hand-crafted by a skilled illustrator. A consequent user study of initial visualization will trigger computational synthesis of a new, quantitatively more effective visualization technique. The visualization designs developed through several iterations of the study-redesign cycle will become declarative, aiming at optimally satisfying the purpose of the visualization, instead of explicit execution of algorithms on the input data. The declarative component will be specified by collected user statistics from completing certain perceptual or cognitive tasks. The user statistics will be analyzed for systematic trends in human perceptual and cognitive performance. These trends will form a basis for visualization redesign. Final satisfactory visualization will evolve over several design iterations.", event = "SCCG 2013", location = "Smolenice castle, Slovakia", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/Viola_Ivan_2013_DC/", } @article{Birkeland-2012-IMC, title = "Illustrative Membrane Clipping", author = "{\AA}smund Birkeland and Stefan Bruckner and Andrea Brambilla and Ivan Viola", year = "2012", abstract = "Clipping is a fast, common technique for resolving occlusions. It only requires simple interaction, is easily understandable, and thus has been very popular for volume exploration. However, a drawback of clipping is that the technique indiscriminately cuts through features. Illustrators, for example, consider the structures in the vicinity of the cut when visualizing complex spatial data and make sure that smaller structures near the clipping plane are kept in the image and not cut into fragments. In this paper we present a new technique, which combines the simple clipping interaction with automated selective feature preservation using an elastic membrane. In order to prevent cutting objects near the clipping plane, the deformable membrane uses underlying data properties to adjust itself to salient structures. To achieve this behaviour, we translate data attributes into a potential field which acts on the membrane, thus moving the problem of deformation into the soft-body dynamics domain. This allows us to exploit existing GPU-based physics libraries which achieve interactive frame rates. For manual adjustment, the user can insert additional potential fields, as well as pinning the membrane to interesting areas. We demonstrate that our method can act as a flexible and non-invasive replacement of traditional clipping planes.", month = jun, journal = "Computer Graphics Forum", volume = "31", number = "3", note = "presented at EuroVis 2012", pages = "905--914", keywords = "illustrative visualization, volume rendering, clipping", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/Birkeland-2012-IMC/", } @inproceedings{Ford-2012-HRV, title = "HeartPad: Real-Time Visual Guidance for Cardiac Ultrasound", author = "Steven Ford and Gabriel Kiss and Ivan Viola and Stefan Bruckner and Hans Torp", year = "2012", abstract = "Medical ultrasound is a challenging modality when it comes to image interpretation. The goal we address in this work is to assist the ultrasound examiner and partially alleviate the burden of interpretation. We propose to address this goal with visualization that provides clear cues on the orientation and the correspondence between anatomy and the data being imaged. Our system analyzes the stream of 3D ultrasound data and in real-time identifies distinct features that are basis for a dynamically deformed mesh model of the heart. The heart mesh is composited with the original ultrasound data to create the data-to-anatomy correspondence. The visualization is broadcasted over the internet allowing, among other opportunities, a direct visualization on the patient on a tablet computer. The examiner interacts with the transducer and with the visualization parameters on the tablet. Our system has been characterized by domain specialist as useful in medical training and for navigating occasional ultrasound users.", booktitle = "Proceedings of the Workshop at SIGGRAPH Asia 2012", keywords = "medical visualization, ultrasound", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/Ford-2012-HRV/", } @inproceedings{Balabanian-2010-IIV, title = "Interactive Illustrative Visualization of Hierarchical Volume Data", author = "Jean-Paul Balabanian and Ivan Viola and Eduard Gr\"{o}ller", year = "2010", abstract = "In scientific visualization the underlying data often has an inherent abstract and hierarchical structure. Therefore, the same dataset can simultaneously be studied with respect to its characteristics in the three-dimensional space and in the hierarchy space. Often both characteristics are equally important to convey. For such scenarios we explore the combination of hierarchy visualization and scientific visualization, where both data spaces are effectively integrated. We have been inspired by illustrations of species evolutions where hierarchical information is often present. Motivated by these traditional illustrations, we introduce integrated visualizations for hierarchically organized volumetric datasets. The hierarchy data is displayed as a graph, whose nodes are visually augmented to depict the corresponding 3D information. These augmentations include images due to volume raycasting, slicing of 3D structures, and indicators of structure visibility from occlusion testing. New interaction metaphors are presented that extend visualizations and interactions, typical for one visualization space, to control visualization parameters of the other space. Interaction on a node in the hierarchy influences visual representations of 3D structures and vice versa. We integrate both the abstract and the scientific visualizations into one view which avoids frequent refocusing typical for interaction with linked-view layouts. We demonstrate our approach on different volumetric datasets enhanced with hierarchical information.", month = jun, location = "Ottawa, Ontario, Canada", booktitle = "Proceedings of Graphics Interface 2010", pages = "137--144", keywords = "visualization, volume data, hierarchical", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/Balabanian-2010-IIV/", } @article{solteszova-2010-MOS, title = "A Multidirectional Occlusion Shading Model for Direct Volume Rendering", author = "Veronika Solteszova and Daniel Patel and Stefan Bruckner and Ivan Viola", year = "2010", abstract = "In this paper, we present a novel technique which simulates directional light scattering for more realistic interactive visualization of volume data. Our method extends the recent directional occlusion shading model by enabling light source positioning with practically no performance penalty. Light transport is approximated using a tilted cone-shaped function which leaves elliptic footprints in the opacity buffer during slice-based volume rendering. We perform an incremental blurring operation on the opacity buffer for each slice in front-to-back order. This buffer is then used to define the degree of occlusion for the subsequent slice. Our method is capable of generating high-quality soft shadowing effects, allows interactive modification of all illumination and rendering parameters, and requires no pre-computation.", month = jun, journal = "Computer Graphics Forum", volume = "29", number = "3", pages = "883--891", keywords = "global illumination, volume rendering, shadows, optical model", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/solteszova-2010-MOS/", } @inproceedings{patel-2010-SVV, title = "Seismic Volume Visualization for Horizon Extraction", author = "Daniel Patel and Stefan Bruckner and Ivan Viola and Eduard Gr\"{o}ller", year = "2010", abstract = "Seismic horizons indicate change in rock properties and are central in geoscience interpretation. Traditional interpretation systems involve time consuming and repetitive manual volumetric seeding for horizon growing. We present a novel system for rapidly interpreting and visualizing seismic volumetric data. First we extract horizon surface-parts by preprocessing the seismic data. Then during interaction the user can assemble in realtime the horizon parts into horizons. Traditional interpretation systems use gradient-based illumination models in the rendering of the seismic volume and polygon rendering of horizon surfaces. We employ realtime gradientfree forward-scattering in the rendering of seismic volumes yielding results similar to high-quality global illumination. We use an implicit surface representation of horizons allowing for a seamless integration of horizon rendering and volume rendering. We present a collection of novel techniques constituting an interpretation and visualization system highly tailored to seismic data interpretation.", month = mar, location = "Taipei, Taiwan", booktitle = "Proceedings of IEEE Pacific Visualization 2010", pages = "73--80", keywords = "volume visualization, horizon extraction, seismic data", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/patel-2010-SVV/", } @article{bruckner-2010-HVC, title = "Hybrid Visibility Compositing and Masking for Illustrative Rendering", author = "Stefan Bruckner and Peter Rautek and Ivan Viola and Mike Roberts and Mario Costa Sousa and Eduard Gr\"{o}ller", year = "2010", abstract = "In this paper, we introduce a novel framework for the compositing of interactively rendered 3D layers tailored to the needs of scientific illustration. Currently, traditional scientific illustrations are produced in a series of composition stages, combining different pictorial elements using 2D digital layering. Our approach extends the layer metaphor into 3D without giving up the advantages of 2D methods. The new compositing approach allows for effects such as selective transparency, occlusion overrides, and soft depth buffering. Furthermore, we show how common manipulation techniques such as masking can be integrated into this concept. These tools behave just like in 2D, but their influence extends beyond a single viewpoint. Since the presented approach makes no assumptions about the underlying rendering algorithms, layers can be generated based on polygonal geometry, volumetric data, pointbased representations, or others. Our implementation exploits current graphics hardware and permits real-time interaction and rendering.", journal = "Computers & Graphics", number = "34", pages = "361--369", keywords = "compositing, masking, illustration", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/bruckner-2010-HVC/", } @inproceedings{balabanian-2008-hvv, title = "Hierarchical Volume Visualization of Brain Anatomy", author = "Jean-Paul Balabanian and Martin Ystad and Ivan Viola and Arvid Lundervold and Helwig Hauser and Eduard Gr\"{o}ller", year = "2008", month = oct, isbn = "978-3-89838-609-8", location = "Konstanz, Deutschland", editor = "Oliver Deussen, Daniel Keim, Dietmar Saupe", booktitle = "VMV 2008, Vision, Modeling and Visualization", pages = "313--322", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/balabanian-2008-hvv/", } @misc{balabanian-2008-tst, title = "Temporal Styles for Time-Varying Volume Data", author = "Jean-Paul Balabanian and Ivan Viola and Torsten M\"{o}ller and Eduard Gr\"{o}ller", year = "2008", abstract = "This paper introduces interaction mechanisms for conveying temporal characteristics of time-varying volume data based on temporal styles. We demonstrate the flexibility of the new concept through different temporal style transfer function types and we define a set of temporal compositors as operators on them. The data is rendered by a multi-volume GPU raycaster that does not require any grid alignment over the individual time-steps of our data nor a rectilinear grid structure. The paper presents the applicability of the new concept on different data sets from partial to full voxel alignment with rectilinear and curvilinear grid layout.", month = jun, note = "POSTER PRESENTATION", location = "Atlanta, Georgia, USA", editor = "Stephan Gumhold, Jana Kosecka and Oliver Staadt", booktitle = "Proceedings of 3DPVT", Conference date = "Poster presented at (2008-06-18--2008-06-20)", note = "81--89", pages = "81 – 89", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/balabanian-2008-tst/", } @misc{Rautek-2008-kav, title = "Visual Abstractions and Interaction Metaphors for Knowledge Assisted Volume Visualization", author = "Peter Rautek and Ivan Viola", year = "2008", abstract = "Extended abstract published at Knowledge-assisted Visualization Workshop (colocated with the IEEE Visualization 2008 conference): http://kav.cs.wright.edu/", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/Rautek-2008-kav/", } @inproceedings{ruiz-2008-OVR, title = "Obscurance-based Volume Rendering Framework", author = "Marc Ruiz and Imma Boada and Ivan Viola and Stefan Bruckner and Miquel Feixas and Mateu Sbert", year = "2008", abstract = "Obscurances, from which ambient occlusion is a particular case, is a technology that produces natural-looking lighting effects in a faster way than global illumination. Its application in volume visualization is of special interest since it permits us to generate a high quality rendering at a low cost. In this paper, we propose an obscurance-based framework that allows us to obtain realistic and illustrative volume visualizations in an interactive manner. Obscurances can include color bleeding effects without additional cost. Moreover, we obtain a saliency map from the gradient of obscurances and we show its application to enhance volume visualization and to select the most salient views.", booktitle = "Proceedings of Volume Graphics 2008", keywords = "volume rendering, illustrative visualization, ambient occlusion", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/ruiz-2008-OVR/", } @misc{Rautek-2008-VF, title = "Illustrative Visualization – New Technology or Useless Tautology?", author = "Peter Rautek and Stefan Bruckner and Eduard Gr\"{o}ller and Ivan Viola", year = "2008", abstract = "This article can be accessed online in the ACM SIGGRAPH, Computer Graphics Quarterly, Volume 42, Number 3: http://www.siggraph.org/publications/newsletter/volume-42-number-3/illustrative-visualization-2013-new-technology-or-useless-tautology", note = "online journal, without talk", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/Rautek-2008-VF/", } @inproceedings{ruiz-2008-SEV, title = "Similarity-based Exploded Views", author = "Marc Ruiz and Ivan Viola and Imma Boada and Stefan Bruckner and Miquel Feixas and Mateu Sbert", year = "2008", abstract = "Exploded views are often used in illustration to overcome the problem of occlusion when depicting complex structures. In this paper, we propose a volume visualization technique inspired by exploded views that partitions the volume into a number of parallel slabs and shows them apart from each other. The thickness of slabs is driven by the similarity between partitions. We use an information-theoretic technique for the generation of exploded views. First, the algorithm identifies the viewpoint from which the structure is the highest. Then, the partition of the volume into the most informative slabs for exploding is obtained using two complementary similarity-based strategies. The number of slabs and the similarity parameter are freely adjustable by the user.", booktitle = "Proceedings of Smart Graphics 2008", pages = "154--165", keywords = "volume visualization, illustrative visualization, exploded views", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/ruiz-2008-SEV/", } @inproceedings{viola-2007-ort, title = "On the Role of Topology in Focus+Context Visualization", author = "Ivan Viola and Eduard Gr\"{o}ller", year = "2007", abstract = "In this paper three types of visualization scenarios are discussed, where topology improves the readability of particular visualization results. The rst type combines topology information represented by simple graphical primitives with other forms of visual representations. The second type uses the topology information to de ne the relevance of objects within the data. The relevance is re ected in the visualization by applying the cut-away concept. The third type of visualizations is based on the change of topology of the underlying data to increase visibility of the most interesting information. Every type handles topology in a di erent way. This illustrates various roles of topology in scienti c visualization.", month = sep, publisher = "Springer", note = "Konferenz hat 2005 stattgefunden, Proceeding ist allerdings erst 2007 erschienen", location = "Budmerice, Slovakia", editor = "H. Hauser, H. Hagen, H. Theisel", booktitle = "Proceedings of TopoInVis 2005, Topology-based Methods in Visualization", pages = "171--181", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/viola-2007-ort/", } @inproceedings{toth-2007-ndd, title = "N-dimensional Data-Dependent Reconstruction Using Topological Changes", author = "Zsolt Toth and Ivan Viola and Andrej Ferko and Eduard Gr\"{o}ller", year = "2007", abstract = "We introduce a new concept for a geometrically based feature preserving reconstruction technique of n-dimensional scattered data. Our goal is to generate an n-dimensional triangulation, which preserves the high frequency regions via local topology changes. It is the generalization of a 2D reconstruction approach based on data-dependent triangulation and Lawson‘s optimization procedure. The definition of the mathematic optimum of the reconstruction is given. We discuss an original cost function and a generalization of known functions for the n-dimensional case.", month = sep, publisher = "Springer", note = "Konferenz hat 2005 stattgefunden, Proceeding ist allerdings erst 2007 erschienen", location = "Budmerice, Slovakia", editor = "H. Hauser, H. Hagen, H. Theisel", booktitle = "Proceedings of TopoInVis 2005, Topology-based Methods in Visualization", pages = "183--198", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/toth-2007-ndd/", } @inproceedings{burns-2007-fea, title = "Feature Emphasis and Contextual Cutaways for Multimodal Medical Visualization", author = "Michael Burns and Martin Haidacher and Wolfgang Wein and Ivan Viola and Eduard Gr\"{o}ller", year = "2007", abstract = "Dense clinical data like 3D Computed Tomography (CT) scans can be visualized together with real-time imaging for a number of medical intervention applications. However, it is difficult to provide a fused visualization that allows sufficient spatial perception of the anatomy of interest, as derived from the rich pre-operative scan, while not occluding the real-time image displayed embedded within the volume. We propose an importance-driven approach that presents the embedded data such that it is clearly visible along with its spatial relation to the surrounding volumetric material. To support this, we present and integrate novel techniques for importance specification, feature emphasis, and contextual cutaway generation. We show results in a clinical context where a pre-operative CT scan is visualized alongside a tracked ultrasound image, such that the important vasculature is depicted between the viewpoint and the ultrasound image, while a more opaque representation of the anatomy is exposed in the surrounding area.", month = may, isbn = "9783905673456", publisher = "IEEE", location = "Nork\"{o}pping, Schweden", editor = "K. Museth, T. M\"{o}ller, A. Ynnerman", booktitle = "Proceedings of Eurographics / IEEE VGTC Symposium on Visualization (EuroVis 2007)", pages = "275--282", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/burns-2007-fea/", } @inproceedings{balabanian-2007-ant, title = "Sonar Explorer: A New Tool for Visualization of Fish Schools from 3D Sonar Data", author = "Jean-Paul Balabanian and Ivan Viola and Egil Ona and Ruben Patel and Eduard Gr\"{o}ller", year = "2007", abstract = "We present a novel framework for analysis and visualization of fish schools in 3D sonar surveys. The 3D sonar technology is new and there have not been applications to visualize the data in 3D. We have created an application called Sonar Explorer that satisfies the requirements of domain scientists. Sonar Explorer provides easy and intuitive semi-automatic fish school tracking and survey map generation. The overall pipeline is described and all pipeline stages relevant for visualization are highlighted. We present techniques to deal with 3D sonar data specifics: highly anisotropic volume data aligned on a curvilinear grid. Domain scientists provide initial impressions on interaction and outlook.", month = may, isbn = "9783905673456", publisher = "IEEE", location = "Nork\"{o}pping, Schweden", editor = "K. Museth, T. M\"{o}ller, A. Ynnerman", booktitle = "Data Visualization - EuroVis 2007", pages = "155--162", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/balabanian-2007-ant/", } @misc{tut-vis-2007, title = "IEEE Visualization Tutorial on Illustrative Display and Interaction in Visualization", author = "Ivan Viola and Stefan Bruckner and Mario Costa Sousa and David Ebert and Carlos Correa", year = "2007", abstract = "The area of illustrative visualization is concerned with developing methods to enhance the depiction of scientific data based on principles founded in traditional illustration. The illustration community has century-long experience in adapting their techniques to human perceptual needs in order to generate an effective depiction which conveys the desired message. Thus, their methods can provide us with important insights into visualization problems. In this tutorial, the concepts in illustrative visualization are reviewed. An important aspect here is interaction: while traditional illustrations are commonly only presented as static images, computer-assisted visualization enables interactive exploration and manipulation of complex scientific data. Only by coupling illustrative visualization with effective interaction techniques its full potential can be exploited. The tutorial starts with a general introduction into the area of illustrative visualization. The concept of importance-driven visualization and its applications are presented. Then we proceed with a discussion how traditional abstraction techniques can be applied in an interactive context using importance-based methods. This ranges from low-level appearance to smart viewpoint-dependent visibility techniques such as cutaways or exploded views. Further advanced manipulation strategies are discussed in the third part. The use deformations to enhance visibility of certain features while providing context or to abstract the structure of a complex objects through direct interaction with the data is examined. As many of the presented methods rely on a separation of focus and context, i.e., the important structures in the data have been identified, the tutorial discusses approaches for selecting objects of interest in a three-dimensional environment using intuitive sketch-based interfaces. Since the effectiveness of a user-interface is heavily dependent on the previous knowledge of the user, the last part of the tutorial examines the concept of layering interfaces based on user expertise. Finally, the application of illustrative display and interaction techniques for non-traditional modalities such as mobile devices concludes the tutorial. IEEE Visualization 2007 Tutorial Page: http://vis.computer.org/vis2007/session/tutorials.html#t7 See also previous tutorials on Illustrative Visualization: IEEE Visualization 2006 Tutorial on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-vis-2006/ Eurographics 2006 Tutorial on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-eg-2006/ SIGGRAPH 2006 Course on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-siggraph-2006/ IEEE Visualization 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/Viola-vistutillustrativevis/ Eurographics 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/eg-tut2005-iv/ ", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/tut-vis-2007/", } @article{Rautek06Vis, title = "Caricaturistic Visualization", author = "Peter Rautek and Ivan Viola and Eduard Gr\"{o}ller", year = "2006", abstract = "Caricatures are pieces of art depicting persons or sociological conditions in a non-veridical way. In both cases caricatures are referring to a reference model. The deviations from the reference model are the characteristic features of the depicted subject. Good caricatures exaggerate the characteristics of a subject in order to accent them. The concept of caricaturistic visualization is based on the caricature metaphor. The aim of caricaturistic visualization is an illustrative depiction of characteristics of a given dataset by exaggerating deviations from the reference model. We present the general concept of caricaturistic visualization as well as a variety of examples. We investigate different visual representations for the depiction of caricatures. Further, we present the caricature matrix, a technique to make differences between datasets easily identifiable.", month = nov, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "12", number = "5", issn = "1077-2626", pages = "1085--1092", keywords = "Focus+Context Techniques, Volume Visualization, Illustrative Visualization", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/Rautek06Vis/", } @article{vis-foa, title = "Importance-Driven Focus of Attention", author = "Ivan Viola and Miquel Feixas and Mateu Sbert and Eduard Gr\"{o}ller", year = "2006", abstract = "This paper introduces a concept for automatic focusing on features within a volumetric data set. The user selects a focus, i.e., object of interest, from a set of pre-defined features. Our system automatically determines the most expressive view on this feature. A characteristic viewpoint is estimated by a novel information-theoretic framework which is based on the mutual information measure. Viewpoints change smoothly by switching the focus from one feature to another one. This mechanism is controlled by changes in the importance distribution among features in the volume. The highest importance is assigned to the feature in focus. Apart from viewpoint selection, the focusing mechanism also steers visual emphasis by assigning a visually more prominent representation. To allow a clear view on features that are normally occluded by other parts of the volume, the focusing for example incorporates cut-away views.", month = oct, journal = "IEEE Transactions on Visualization and Computer Graphics", volume = "12", number = "5", pages = "933--940", keywords = "illustrative visualization, interacting with volumetric datasets, optimal viewpoint estimation, focus+context techniques, volume visualization", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/vis-foa/", } @misc{tut-siggraph-2006, title = "SIGGRAPH Course Illustrative Visualization for Medicine and Science", author = "Mario Costa Sousa and David Ebert and Bruce Gooch and Ivan Viola and Stefan Bruckner and Bill Andrews and Don Stredney and Nikolai Svakhine", year = "2006", abstract = "Research and recent development in computer-generated illustration techniques within non-photorealistic rendering. The course concentrates specifically on illustration methods for computer-generated technical, scientific, medical, and interactive illustrations of both surface and volumetric data. It also presents the perspective of two medical illustrators on computerized illustration. ACM SIGGRAPH 2006 course page: http://www.siggraph.org/s2006/main.php?f=conference&p=courses&s=6 Further Information: http://pages.cpsc.ucalgary.ca/~mario/webpage/publ/courses.htm See also previous tutorials on Illustrative Visualization: IEEE Visualization 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/Viola-vistutillustrativevis/ Eurographics 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/eg-tut2005-iv/ ", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/tut-siggraph-2006/", } @talk{viola-2006-FoA, title = "Focus of Attention for Volumetric Data Inspection", author = "Ivan Viola and Miquel Feixas and Mateu Sbert and Eduard Gr\"{o}ller", year = "2006", event = "Dagstuhl Seminar on Computational Aesthetics in Computer Graphics, Visualization, and Imaging", location = "Dagstuhl castle, Germany", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/viola-2006-FoA/", } @misc{viola-popular-article-2006, title = "Explodierende K\"{o}rper", author = "Michael Krassnitzer and Ivan Viola and Stefan Bruckner", year = "2006", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/viola-popular-article-2006/", } @misc{tut-eg-2006, title = "Eurographics Tutorial on Illustrative Visualization for Science and Medicine", author = "Ivan Viola and Mario Costa Sousa and David Ebert and Bernhard Preim and Bruce Gooch and Bill Andrews and Christian Tietjen", year = "2006", abstract = "This tutorial presents recent and important research and developments from academia in illustrative, nonphotorealistic rendering (NPR) focusing on its use for medical/science subjects. Lectures are organized within a comprehensive illustration framework, focusing on three main components: (a) Traditional and computerized illustration techniques and principles for Technical and Science Subjects, (b) Evaluation and Practical Use, (c) Viewing & Rendering. Presentation of topics is balanced between descriptions of traditional methods and practices, practical implementation motivated approaches and evaluation, and detailed descriptions and analysis of NPR techniques and algorithms. We begin with a lecture presenting an overview of traditional illustration in technical, science, and medical subjects followed by a description of the main components in a NPR pipeline for developing systems to help technical and science illustrators with their work. The tutorial progresses with an overview of the NPR used in illustration as well as approaches to evaluate their use and effectiveness. Following lectures describe the latest techniques in computerized illustration algorithms for scientific and medical data for both surface and volumetric data, covering techniques from silhouette enhancement to stippling, to cut-away viewing, labeling, and focus+context rendering. Each of the lectures also discusses practical issues in making these techniques interactive and their use for different application domains. Tutorial concludes with discussion on specific medical case studies where the illustrative visualization has been effectively applied. Eurographics 2006 tutorial page: http://www.cg.tuwien.ac.at/events/EG06/program-t1022.php See also previous tutorials on Illustrative Visualization: SIGGRAPH 2006 Course on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-siggraph-2006/ IEEE Visualization 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/Viola-vistutillustrativevis/ Eurographics 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/eg-tut2005-iv/", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/tut-eg-2006/", } @misc{tut-vis-2006, title = "IEEE Visualization Tutorial on Illustrative Visualization for Science and Medicine", author = "Ivan Viola and Mario Costa Sousa and David Ebert and Bill Andrews and Bruce Gooch and Stefan Bruckner and Bernhard Preim and Don Stredney and Nikolai Svakhine and Christian Tietjen", year = "2006", abstract = "This tutorial presents recent research and developments from academia in illustrative visualization focusing on its use for medical/science subjects. Lectures are organized within a comprehensive illustration framework, focusing on three main components: • Traditional and computerized illustration techniques and principles for technical and scientific subjects • Evaluation and practical use • Viewing & rendering Presentation of topics is balanced between descriptions of traditional methods and practices, practical implementation motivated approaches and evaluation, and detailed descriptions and analysis of illustrative techniques and algorithms. We begin in the morning with a lecture presenting an overview of traditional illustration for technical, scientific, and medical subjects. This is followed by a description of the main components in an illustrative visualization pipeline for developing systems to assist technical and scientific illustrators. The tutorial progresses with an overview of the techniques used in illustration as well as approaches to evaluate their use and effectiveness. The morning concludes with the start of the “viewing and rendering” section. The three lectures in this section describe the latest approaches in computerized illustration algorithms for scientific and medical data for both surface and volumetric data, covering techniques from silhouette enhancement to stippling, to cut-away viewing, labeling, and focus+context rendering. Each of the lectures also discusses practical issues in making these techniques interactive and their use for different application domains. The tutorial includes a trained medical illustrator discussing the principles/caveats/issues in using illustration techniques in real-world medical applications. This lecture will also describe an evaluation, from an illustrator’s point of view, of the use and quality of the techniques presented throughout the day. The tutorial concludes with discussion on specific medical case studies where illustrative visualization has been effectively applied. IEEE Visualization 2006 Tutorial Page: http://vis.computer.org/vis2006/session/tutorials.html#t3 See also previous tutorials on Illustrative Visualization: Eurographics 2006 Tutorial on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-eg-2006/ SIGGRAPH 2006 Course on Illustrative Visualization for Science and Medicine http://www.cg.tuwien.ac.at/research/publications/2006/tut-siggraph-2006/ IEEE Visualization 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/Viola-vistutillustrativevis/ Eurographics 2005 Tutorial on Illustrative Visualization http://www.cg.tuwien.ac.at/research/publications/2005/eg-tut2005-iv/ ", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/tut-vis-2006/", } @tv{xmastree2005, title = "X-rayed X-mastree", author = "Armin Kanitsar and Ivan Viola and Katja B\"{u}hler and Stefan Bruckner", year = "2005", abstract = "Further information can be found on: http://www.br-online.de/wissen-bildung/sendungen/faszinationwissen/magazin17.xml", month = dec, URL = "https://www.cg.tuwien.ac.at/research/publications/2005/xmastree2005/", } @misc{bruckner-2005-vid, title = "VolumeShop: Interactive Direct Volume Illustration", author = "Stefan Bruckner and Ivan Viola and Eduard Gr\"{o}ller", year = "2005", abstract = "Illustrations play a major role in the education process. Whether used to teach a surgical or radiologic procedure, to illustrate normal or aberrant anatomy, or to explain the functioning of a technical device, illustration significantly impacts learning. Many specimen are readily available as volumetric data sets, particular in medicine. Illustrations, however, are commonly produced manually as static images in a time-consuming process. Our goal is to create a fully dynamic three-dimensional illustration environment which directly operates on volume data. Single images have the aesthetic appeal of traditional illustrations, but can be interactively altered and explored. We present methods to realize such a system which combines artistic visual styles and expressive visualization techniques. Our implementation exploits the latest generation of GPUs and, thus, is capable of handling commonly sized data sets at interactive frame rates. ", month = aug, booktitle = "ACM Siggraph 2005 DVD Proceedings (Technical Sketch)", keywords = "focus+context techniques, volume rendering, illustrative techniques", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/bruckner-2005-vid/", } @inproceedings{Artner-2005-Hig, title = "High-Quality Volume Rendering with Resampling in the Frequency Domain", author = "Martin Artner and Torsten M\"{o}ller and Ivan Viola and Eduard Gr\"{o}ller", year = "2005", abstract = "This work introduces a volume rendering technique that is conceptually based on the shear-warp factorization. We propose to perform the shear transformation entirely in the frequency domain. Unlike the standard shear-warp algorithm, we allow for arbitrary sampling distances along the viewing rays, independent of the view direction. The accurate scaling of the volume slices is achieved by using the zero padding interpolation property. Finally, a high quality gradient estimation scheme is presented which uses the derivative theorem of the Fourier transform. Experimental results have shown that the presented method outperforms established algorithms in the quality of the produced images. If the data is sampled above the Nyquist rate the presented method is capable of a perfect reconstruction of the original function.", month = jun, isbn = "3-905673-19-3", location = "Leeds, United Kingdom", booktitle = "Proceedings of EuroVis", pages = "85--92", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/Artner-2005-Hig/", } @phdthesis{phd-viola, title = "Importance-Driven Expressive Visualization", author = "Ivan Viola", year = "2005", abstract = "In this thesis several expressive visualization techniques for volumetric data are presented. The key idea is to classify the underlying data according to its prominence on the resulting visualization by importance value. The importance property drives the visualization pipeline to emphasize the most prominent features and to suppress the less relevant ones. The suppression can be realized globally, so the whole object is suppressed, or locally. A local modulation generates cut-away and ghosted views because the suppression of less relevant features occurs only on the part where the occlusion of more important features appears. Features within the volumetric data are classified according to a new dimension denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance. An additional step to traditional volume rendering evaluates the areas of occlusion and assigns a particular level of sparseness. This step is denoted as importance compositing. Advanced schemes for importance compositing determine the resulting visibility of features and if the resulting visibility distribution does not correspond to the importance distribution different levels of sparseness are selected. The applicability of importance-driven visualization is demonstrated on several examples from medical diagnostics scenarios, flow visualization, and interactive illustrative visualization.", month = jun, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/phd-viola/", } @inproceedings{Viola-05-Smart, title = "Smart Visibility in Visualization", author = "Ivan Viola and Eduard Gr\"{o}ller", year = "2005", abstract = "In this paper we discuss expressive visualization techniques that smartly uncover the most important information in order to maximize the visual information of the underlying data. This is achieved through dynamic change in visual representations, through deformations, or through changing the spatial position of parts of the data. Such techniques originate from technical illustration and are called cut-away views, ghosted views, and exploded views. These illustrative techniques unveil the most important visual information by a high level of abstraction. The change in visual representation or spatial position is done in a way that is easily perceivable and the overall visual harmony is preserved.", month = may, isbn = "3905673274", location = "Girona, Spain", editor = "L. Neumann, M. Sbert, B. Gooch, W. Purgathofer", booktitle = "Proceedings of EG Workshop on Computational Aesthetics Computational Aesthetics in Graphics, Visualization and Imaging", pages = "209--216", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/Viola-05-Smart/", } @article{viola-2005-imp, title = "Importance-Driven Feature Enhancement in Volume Visualization", author = "Ivan Viola and Armin Kanitsar and Eduard Gr\"{o}ller", year = "2005", abstract = "This paper presents importance-driven feature enhancement as a technique for the automatic generation of cut-away and ghosted views out of volumetric data. The presented focus+context approach removes or suppresses less important parts of a scene to reveal more important underlying information. however, less important parts are fully visible in those regions, where important visual information is not lost, i.e., more relevant features are not occluded. Features within the volumetric data are first classified according to a new dimension denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance (importance compositing). The paper includes an extended discussion on several possible schemes for levels of sparseness specification. Furthermore different approaches to importance compositing are treated.", journal = "IEEE Transactions on Visualization and Computer Graphics", number = "4", volume = "11", pages = "408--418", keywords = "non-photorealistic techniques, view-dependent visualization, volume rendering, focus+context techniques, level-of-detail techniques", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/viola-2005-imp/", } @talk{diss-thesis-bratislava, title = "Importance-Driven Expressive Visualization", author = "Ivan Viola", year = "2005", abstract = "In this talk several expressive visualization techniques for volumetric data are presented. The key idea is to classify the underlying data according to its prominence on the resulting visualization by importance value. The importance property drives the visualization pipeline to emphasize the most prominent features and to suppress the less relevant ones. The suppression can be realized globally, so the whole object is suppressed, or locally. A local modulation generates cut-away and ghosted views because the suppression of less relevant features occurs only on the part where the occlusion of more important features appears. Features within the volumetric data are classified according to a new imension denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance. An additional step to traditional volume rendering evaluates the areas of occlusion and assigns a particular level of sparseness. This step is denoted as importance compositing. Advanced schemes for importance compositing determine the resulting visibility of features and if the resulting visibility distribution does not correspond to the importance distribution different levels of sparseness are selected. The applicability of importance-driven visualization is demonstrated on several examples from medical diagnostics scenarios, flow visualization, and interactive illustrative visualization. ", event = "Dissertation Thesis Report", location = "Comenius University Bratislava, Slovakia", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/diss-thesis-bratislava/", } @talk{diss-thesis-siegen, title = "Importance-Driven Expressive Visualization", author = "Ivan Viola", year = "2005", abstract = "In this talk several expressive visualization techniques for volumetric data are presented. The key idea is to classify the underlying data according to its prominence on the resulting visualization by importance value. The importance property drives the visualization pipeline to emphasize the most prominent features and to suppress the less relevant ones. The suppression can be realized globally, so the whole object is suppressed, or locally. A local modulation generates cut-away and ghosted views because the suppression of less relevant features occurs only on the part where the occlusion of more important features appears. Features within the volumetric data are classified according to a new imension denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance. An additional step to traditional volume rendering evaluates the areas of occlusion and assigns a particular level of sparseness. This step is denoted as importance compositing. Advanced schemes for importance compositing determine the resulting visibility of features and if the resulting visibility distribution does not correspond to the importance distribution different levels of sparseness are selected. The applicability of importance-driven visualization is demonstrated on several examples from medical diagnostics scenarios, flow visualization, and interactive illustrative visualization. ", event = "Dissertation Thesis Report", location = "University of Siegen, Germany", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/diss-thesis-siegen/", } @misc{Viola-vistutillustrativevis, title = "IEEE Visualization Tutorial on Illustrative Visualization", author = "Ivan Viola and Eduard Gr\"{o}ller and Katja B\"{u}hler and Markus Hadwiger and Bernhard Preim and David Ebert and Mario Costa Sousa and Don Stredney", year = "2005", abstract = "The tutorial presents state-of-the-art visualization techniques inspired by traditional technical and medical illustrations. Such techniques exploit the perception of the human visual system and provide effective visual abstractions to make the visualization clearly understandable. Visual emphasis and abstraction has been used for expressive presentation from prehistoric paintings to nowadays scientific and medical illustrations. Many of the expressive techniques used in art are adopted in computer graphics, and are denoted as illustrative or non-photorealistic rendering. Different stroke techniques, or brush properties express a particular level of abstraction. Feature emphasis or feature suppression is achieved by combining different abstraction levels in illustrative rendering. Challenges in visualization research are very large data visualization as well as multi-dimensional data visualization. To effectively convey the most important visual information there is a significant need for visual abstraction. For less relevant information the dedicated image space is reduced to enhance more prominent features. The discussed techniques in the context of scientic visualization are based on iso-surfaces and volume rendering. Apart from visual abstraction, i.e., illustrative representation, the visibility of prominent features can be achieved by illustrative visualization techniques such as cut-away views or ghosted views. The structures that occlude the most prominent information are suppressed in order to clearly see more interesting parts. A different smart way to provide information on the data is using exploded views or other types of deformation. Furthermore intuitive feature classification via 3D painting and manipulation with the classified data including label placement is presented. Discussed non-photorealistic and illustrative techniques from visualization and graphics are shown from the perspective as tools for illustrators from medicine, botany, archeology, and zoology. The limitations of existing NPR systems for science illustration are highlighted, and proposals for possible new directions are made. Illustrative visualization is demonstrated via application-specific tasks in medical visualization. An important aspect as compared to traditional medical illustrations is the interactivity and real-time manipulation of the acquired patient data. This can be very useful in anatomy education. Another application area is surgical planning which is demonstrated with two case studies: neck dissection and liver surgery planning.", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/Viola-vistutillustrativevis/", } @talk{diss-thesis-magdeburg, title = "Importance-Driven Expressive Visualization", author = "Ivan Viola", year = "2005", abstract = "In this talk several expressive visualization techniques for volumetric data are presented. The key idea is to classify the underlying data according to its prominence on the resulting visualization by importance value. The importance property drives the visualization pipeline to emphasize the most prominent features and to suppress the less relevant ones. The suppression can be realized globally, so the whole object is suppressed, or locally. A local modulation generates cut-away and ghosted views because the suppression of less relevant features occurs only on the part where the occlusion of more important features appears. Features within the volumetric data are classified according to a new imension denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance. An additional step to traditional volume rendering evaluates the areas of occlusion and assigns a particular level of sparseness. This step is denoted as importance compositing. Advanced schemes for importance compositing determine the resulting visibility of features and if the resulting visibility distribution does not correspond to the importance distribution different levels of sparseness are selected. The applicability of importance-driven visualization is demonstrated on several examples from medical diagnostics scenarios, flow visualization, and interactive illustrative visualization. ", event = "Dissertation Thesis Report", location = "University of Magdeburg, Germany", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/diss-thesis-magdeburg/", } @misc{eg-tut2005-iv, title = "Eurographics Tutorial on Illustrative Visualization", author = "Ivan Viola and Eduard Gr\"{o}ller and Katja B\"{u}hler and Markus Hadwiger and Bernhard Preim and David Ebert", year = "2005", abstract = "The tutorial presents state-of-the-art visualization techniques inspired by traditional technical and medical illustrations. Such techniques exploit the perception of the human visual system and provide effective visual abstractions to make the visualization clearly understandable. Visual emphasis and abstraction has been used for expressive presentation from prehistoric paintings to nowadays scientific and medical illustrations. Many of the expressive techniques used in art are adopted in computer graphics, and are denoted as illustrative or non-photorealistic rendering. Different stroke techniques, or brush properties express a particular level of abstraction. Feature emphasis or feature suppression is achieved by combining different abstraction levels in illustrative rendering. Challenges in visualization research are very large data visualization as well as multi-dimensional data visualization. To effectively convey the most important visual information there is a significant need for visual abstraction. For less relevant information the dedicated image space is reduced to enhance more prominent features. The discussed techniques in the context of scientific visualization are based on iso-surfaces and volume rendering. Apart from visual abstraction, i.e., illustrative representation, the visibility of prominent features can be achieved by illustrative visualization techniques such as cut-away views or ghosted views. The structures that occlude the most prominent information are suppressed in order to clearly see more interesting parts. Another smart way to provide information on the data is using exploded views or other types of deformation. Illustrative visualization is demonstrated via application-specific tasks in medical visualization. An important aspect as compared to traditional medical illustrations is the interactivity and real-time manipulation of the acquired patient data. This can be very useful in anatomy education. Another application area is surgical planning which is demonstrated with two case studies: neck dissection and liver surgery planning.", booktitle = "Tutorial Notes on Illustrative Visualization", publisher = "Eurographics", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/eg-tut2005-iv/", } @inproceedings{Viola-2004-ImpX2, title = "Importance-Driven Volume Rendering", author = "Ivan Viola and Armin Kanitsar and Eduard Gr\"{o}ller", year = "2004", abstract = "This paper introduces importance-driven volume rendering as a novel technique for automatic focus and context display of volumetric data. Our technique is a generalization of cut-away views, which – depending on the viewpoint – remove or suppress less important parts of a scene to reveal more important underlying information. We automatize and apply this idea to volumetric data. Each part of the volumetric data is assigned an object importance which encodes visibility priority. This property determines which structures should be readily discernible and which structures are less important. In those image regions, where an object occludes more important structures it is displayed more sparsely than in those areas where no occlusion occurs. Thus the objects of interest are clearly visible. For each object several representations, i.e., levels of sparseness, are specified. The display of an individual object may incorporate different levels of sparseness. The goal is to emphasize important structures and to maximize the information content in the final image. This paper also discusses several possible schemes for level of sparseness specification and different ways how object importance can be composited to determine the final appearance of a particular object.", month = oct, isbn = "0780387880", publisher = "H. Rushmeier, G. Turk, J. van Wijk", booktitle = "Proceedings of IEEE Visualization 2004", pages = "139--145", keywords = "view-dependent visualization, non-photorealistic techniques, level-of-detail techniques, focus+context techniques, volume rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/Viola-2004-ImpX2/", } @inproceedings{Viola-2004-GPU, title = "GPU-based Frequency Domain Volume Rendering", author = "Ivan Viola and Armin Kanitsar and Eduard Gr\"{o}ller", year = "2004", abstract = "Frequency domain volume rendering (FVR) is a volume rendering technique with lower computational complexity as compared to other techniques. In this paper the FVR algorithm is accelerated by factor of 17 by mapping the rendering stage to the GPU. The overall hardware-accelerated pipeline is discussed and the changes according to previous work are pointed out. The three-dimensional transformation into frequency domain is done in a pre-processing step. The rendering step is computed completely on the GPU. First the projection slice is extracted. Four different interpolation schemes are used for resampling the slice from the data represented by a 3D texture. The extracted slice is transformed back into the spatial domain using the inverse Fast Fourier or Fast Hartley Transform. The rendering stage is implemented through shader programs running on programmable graphics hardware achieving highly interactive framerates.", month = apr, isbn = "80-223-1730-6", note = "second-best paper award!", booktitle = "Proceedings of SCCG 2004", pages = "49--58", keywords = "Fourier Transform, Fourier Volume Rendering, Hardware Acceleration", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/Viola-2004-GPU/", } @talk{viola-2004-gbf, title = "GPU-Based Frequency Domain Volume Rendering", author = "Ivan Viola", year = "2004", event = "SCCG", location = "Budmerice", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/viola-2004-gbf/", } @talk{viola-2004-idv, title = "Importance-Driven Volume Rendering", author = "Ivan Viola", year = "2004", event = "IDVR", location = "Austin, USA", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/viola-2004-idv/", } @inproceedings{Viola-2003-Har, title = "Hardware-Based Nonlinear Filtering and Segmentation using High-Level Shading Languages.", author = "Ivan Viola and Armin Kanitsar and Eduard Gr\"{o}ller", year = "2003", abstract = "Non-linear filtering is an important task for volume analysis. This paper presents hardware-based implementations of various nonlinear filters for volume smoothing with edge preservation. The Cg high-level shading language is used in combination with latest PC consumer graphics hardware. Filtering is divided into pervertex and per-fragment stages. In both stages we propose techniques to increase the filtering performance. The vertex program pre-computes texture coordinates in order to address all contributing input samples of the operator mask. Thus additional computations are avoided in the fragment program. The presented fragment programs preserve cache coherence, exploit 4D vector arithmetic, and internal fixed point arithmetic to increase performance. We show the applicability of non-linear filters as part of a GPU-based segmentation pipeline. The resulting binary mask is compressed and decompressed in the graphics memory on-the-fly.", month = oct, isbn = "0780381203", publisher = "IEEE", editor = "G. Turk, J. van Wijk, K. Moorhead", booktitle = "Proceedings of IEEE Visualization 2003", pages = "309--316", keywords = "Hardware Acceleration, Segmentation, Non-linear Filtering", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Viola-2003-Har/", } @talk{viola-2003-hbn, title = "Hardware-Based Nonlinear Filtering and Segmentation using High-Level Shading Languages Visualization", author = "Ivan Viola", year = "2003", event = "Visualization", location = "Seattle, USA", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/viola-2003-hbn/", } @inproceedings{Hadwiger-2002-Fas, title = "Fast and Flexible High-Quality Texture Filtering With Tiled High-Resolution Filters", author = "Markus Hadwiger and Ivan Viola and Thomas Theu{\ss}l and Helwig Hauser", year = "2002", abstract = "Current graphics hardware offers only very limited support for convolution operations, which is primarily intended for image processing. The input and output sample grids have to coincide, making it impossible to use these features for more general filtering tasks such as image or texture resampling. Furthermore, most hardware employs linear interpolation for texture reconstruction purposes, incurring noticeable artifacts. Higher-order interpolation via general convolution is able to remove most of these artifacts. Real-time applications currently do not consider higher-order filtering due to lack of hardware support. We present algorithms for extremely fast convolution on graphics hardware. This framework can be used for general convolution tasks, but is especially suited to substituting the native bilinear or tri-linear interpolation currently used for texture magnification, while still achieving frame rates of up to 100 frames per second for full screen filtering with bi-cubic interpolation.", month = nov, publisher = "Akademische Verlagsgesellschaft Aka GmbH, Berlin", booktitle = "Vision, Modeling and Visualization 2002", pages = "155--162", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Hadwiger-2002-Fas/", } @inproceedings{Neumann-2002-Fea, title = "Feature-Preserving Volume Filtering", author = "L\'{a}szl\'{o} Neumann and Bal\'{a}zs Cs\'{e}bfalvi and Ivan Viola and Matej Mlejnek and Eduard Gr\"{o}ller", year = "2002", abstract = "In this paper a feature-preserving volume filtering method is presented. The basic idea is to minimize a three-component global error function penalizing the density and gradient errors and the curvature of the unknown filtered function. The optimization problem leads to a large linear equation system defined by a sparse coefficient matrix. We will show that such an equation system can be efficiently solved in frequency domain using fast Fourier transformation (FFT). For the sake of clarity, first we illustrate our method on a 2D example which is a dedithering problem. Afterwards the 3D extension is discussed in detail since we propose our method mainly for volume filtering. We will show that the 3D version can be efficiently used for elimination of the typical staircase artifacts of direct volume rendering without losing fine details. Unlike local filtering techniques, our novel approach ensures a global smoothing effect. Previous global 3D methods are restricted to binary volumes or segmented iso-surfaces and they are based on area minimization of one single reconstructed surface. In contrast, our method is a general volume-filtering technique, implicitly smoothing all the iso-surfaces at the same time. Although the strength of the presented algorithm is demonstrated on a specific 2D and a specific 3D application, it is considered as a general mathematical tool for processing images and volumes.", month = may, publisher = "ACM", booktitle = "Data Visualization 2002", pages = "105--114", keywords = "antialiasing, noise filtering, derivative and gradient estimation, feature-preserving smoothing, direct volume rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Neumann-2002-Fea/", } @mastersthesis{Masterthesis-Viola, title = "Applications of Hardware-Accelerated Filtering in Computer Graphics", author = "Ivan Viola", year = "2002", abstract = "Two of the most important issues of computer graphics – especially in raster graphics and volume visualisation – are sampling and reconstruction. These operations must fulfill particular conditions of sampling theory in order to be able to represent arbitrary continuous functions by discrete samples and reconstruct them from these samples without significant information loss. Several approaches for high-quality reconstruction have been introduced to the computer graphics community. These approaches are mostly implemented in software, possible only as pre-process step. The only two ways of reconstruction that are usually fast enough for real-time rendering are nearest neighbor and linear interpolation filtering, but the quality of these filtering processes is often not sufficient. This work summarizes the hardware-based methods that exploit the features of today’s graphics chips for filtering tasks. These methods are divided in two parts, i.e., high-resolution filtering and image processing. Both methods are based on the distribution principle of convolution known from splatting based volume rendering algorithms and they share the same general principle. The difference is in the implementation of the algorithms themselves. High-resolution filtering employs high-order filters in order to improve the quality of resampling tremendously. The implemented algorithms exploit symmetry or separability properties to make the filtering more efficient. We compare it to the existing, natively supported solution, i.e., linear interpolation to our filtering implementation using higher order filters. This is shown in various application areas like surface-texturing, and solid-texturing, animated textures, or derivative filtering; at interactive framerates. The image processing algorithms are simplified general filtering algorithms to increase effciency and performance. We show the usability on smoothing and edge detection, the important operations of image processing and pattern recognition. We combine this techniques together with other hardware features to provide hardware-accelerated artistic rendering techniques. These are also presented in a rendering system that provides non-photorealistic rendering effects.", month = apr, note = "1", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Masterthesis-Viola/", }