@article{zsolnaifeher-2020-pme, title = "Photorealistic Material Editing Through Direct Image Manipulation", author = "Karoly Zsolnai-Feh\'{e}r and Peter Wonka and Michael Wimmer", year = "2020", abstract = "Creating photorealistic materials for light transport algorithms requires carefully fine-tuning a set of material properties to achieve a desired artistic effect. This is typically a lengthy process that involves a trained artist with specialized knowledge. In this work, we present a technique that aims to empower novice and intermediate-level users to synthesize high-quality photorealistic materials by only requiring basic image processing knowledge. In the proposed workflow, the user starts with an input image and applies a few intuitive transforms (e.g., colorization, image inpainting) within a 2D image editor of their choice, and in the next step, our technique produces a photorealistic result that approximates this target image. Our method combines the advantages of a neural network-augmented optimizer and an encoder neural network to produce high-quality output results within 30 seconds. We also demonstrate that it is resilient against poorly-edited target images and propose a simple extension to predict image sequences with a strict time budget of 1-2 seconds per image. Video: https://www.youtube.com/watch?v=8eNHEaxsj18", month = jun, journal = "Computer Graphics Forum", volume = "39", number = "4", issn = "1467-8659", doi = "10.1111/cgf.14057", pages = "14", pages = "107--120", keywords = "neural rendering, neural networks, photorealistic rendering, photorealistic material editing", URL = "https://www.cg.tuwien.ac.at/research/publications/2020/zsolnaifeher-2020-pme/", } @article{nguyen_2020-covid, title = "Modeling in the Time of COVID-19: Statistical and Rule-based Mesoscale Models", author = "Ngan Nguyen and Ondrej Strnad and Tobias Klein and Ruwayda Alharbi and Peter Wonka and Martina Maritan and Peter Mindek and Ludovic Autin and David Goodsell and Ivan Viola", year = "2020", abstract = "We present a new technique for rapid modeling and construction of scientifically accurate mesoscale biological models. Resulting 3D models are based on few 2D microscopy scans and the latest knowledge about the biological entity represented as a set of geometric relationships. Our new technique is based on statistical and rule-based modeling approaches that are rapid to author, fast to construct, and easy to revise. From a few 2D microscopy scans, we learn statistical properties of various structural aspects, such as the outer membrane shape, spatial properties and distribution characteristics of the macromolecular elements on the membrane. This information is utilized in 3D model construction. Once all imaging evidence is incorporated in the model, additional information can be incorporated by interactively defining rules that spatially characterize the rest of the biological entity, such as mutual interactions among macromolecules, their distances and orientations to other structures. These rules are defined through an intuitive 3D interactive visualization and modeling feedback loop. We demonstrate the utility of our approach on a use case of the modeling procedure of the SARS-CoV-2 virus particle ultrastructure. Its first complete atomistic model, which we present here, can steer biological research to new promising directions in fighting spread of the virus.", journal = "IEEE Transactions on Visualization and Computer Graphics", URL = "https://www.cg.tuwien.ac.at/research/publications/2020/nguyen_2020-covid/", } @article{zsolnai-2018-gms, title = "Gaussian Material Synthesis", author = "Karoly Zsolnai-Feh\'{e}r and Peter Wonka and Michael Wimmer", year = "2018", abstract = "We present a learning-based system for rapid mass-scale material synthesis that is useful for novice and expert users alike. The user preferences are learned via Gaussian Process Regression and can be easily sampled for new recommendations. Typically, each recommendation takes 40-60 seconds to render with global illumination, which makes this process impracticable for real-world workflows. Our neural network eliminates this bottleneck by providing high-quality image predictions in real time, after which it is possible to pick the desired materials from a gallery and assign them to a scene in an intuitive manner. Workflow timings against Disney’s “principled” shader reveal that our system scales well with the number of sought materials, thus empowering even novice users to generate hundreds of high-quality material models without any expertise in material modeling. Similarly, expert users experience a significant decrease in the total modeling time when populating a scene with materials. Furthermore, our proposed solution also offers controllable recommendations and a novel latent space variant generation step to enable the real-time fine-tuning of materials without requiring any domain expertise.", month = aug, journal = "ACM Transactions on Graphics (SIGGRAPH 2018)", volume = "37", number = "4", issn = "0730-0301", doi = "10.1145/3197517.3201307", pages = "76:1--76:14", keywords = "gaussian material synthesis, neural rendering, neural rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/zsolnai-2018-gms/", } @article{HECHER-2017-HDY, title = "How Do Users Map Points Between Dissimilar Shapes?", author = "Michael Hecher and Paul Guerrero and Peter Wonka and Michael Wimmer", year = "2018", abstract = "Finding similar points in globally or locally similar shapes has been studied extensively through the use of various point descriptors or shape-matching methods. However, little work exists on finding similar points in dissimilar shapes. In this paper, we present the results of a study where users were given two dissimilar two-dimensional shapes and asked to map a given point in the first shape to the point in the second shape they consider most similar. We find that user mappings in this study correlate strongly with simple geometric relationships between points and shapes. To predict the probability distribution of user mappings between any pair of simple two-dimensional shapes, two distinct statistical models are defined using these relationships. We perform a thorough validation of the accuracy of these predictions and compare our models qualitatively and quantitatively to well-known shape-matching methods. Using our predictive models, we propose an approach to map objects or procedural content between different shapes in different design scenarios.", month = aug, doi = "10.1109/TVCG.2017.2730877", issn = "1077-2626", journal = "IEEE Transactions on Visualization and Computer Graphics", number = "8", volume = "24", pages = "2327--2338", keywords = "shape matching, transformations, shape similarity", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/HECHER-2017-HDY/", } @article{birsak-2017-dpe, title = "Dynamic Path Exploration on Mobile Devices", author = "Michael Birsak and Przemyslaw Musialski and Peter Wonka and Michael Wimmer", year = "2018", abstract = "We present a novel framework for visualizing routes on mobile devices. Our framework is suitable for helping users explore their environment. First, given a starting point and a maximum route length, the system retrieves nearby points of interest (POIs). Second, we automatically compute an attractive walking path through the environment trying to pass by as many highly ranked POIs as possible. Third, we automatically compute a route visualization that shows the current user position, POI locations via pins, and detail lenses for more information about the POIs. The visualization is an animation of an orthographic map view that follows the current user position. We propose an optimization based on a binary integer program (BIP) that models multiple requirements for an effective placement of detail lenses. We show that our path computation method outperforms recently proposed methods and we evaluate the overall impact of our framework in two user studies.", month = may, doi = "10.1109/TVCG.2017.2690294", issn = "1077-2626", journal = "IEEE Transactions on Visualization and Computer Graphics", number = "5", volume = "24", pages = "1784--1798", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/birsak-2017-dpe/", } @article{Birsak2018-SA, title = "String Art: Towards Computational Fabrication of String Images", author = "Michael Birsak and Florian Rist and Peter Wonka and Przemyslaw Musialski", year = "2018", abstract = "In this paper we propose a novel method for the automatic computation and digital fabrication of artistic string images. String art is a technique used by artists for the creation of abstracted images which are composed of straight lines of strings ten- sioned between pins distributed on a frame. Together the strings fuse to a perceptible image. Traditionally, artists craft such images manually in a highly sophisticated and tedious design process. To achieve this goal fully automatically we propose a computational setup driven by a discrete optimization algorithm which takes an ordinary picture as input and converts it into a connected graph of strings that tries to reassemble the input image best possibly. Furthermore, we propose a hardware setup for automatic digital fabrication of these images using an industrial robot that spans the strings. Finally, we demonstrate the applicability of our approach by generating and fabricating a set of real string art images.", month = apr, journal = "Computer Graphics Forum (Proc. EUROGRAPHICS 2018)", volume = "37", number = "2", doi = "10.1111/cgf.13359", pages = "accepted", pages = "263--274", URL = "https://www.cg.tuwien.ac.at/research/publications/2018/Birsak2018-SA/", } @article{guerrero-2015-lsp, title = "Learning Shape Placements by Example", author = "Paul Guerrero and Stefan Jeschke and Michael Wimmer and Peter Wonka", year = "2015", abstract = "We present a method to learn and propagate shape placements in 2D polygonal scenes from a few examples provided by a user. The placement of a shape is modeled as an oriented bounding box. Simple geometric relationships between this bounding box and nearby scene polygons define a feature set for the placement. The feature sets of all example placements are then used to learn a probabilistic model over all possible placements and scenes. With this model we can generate a new set of placements with similar geometric relationships in any given scene. We introduce extensions that enable propagation and generation of shapes in 3D scenes, as well as the application of a learned modeling session to large scenes without additional user interaction. These concepts allow us to generate complex scenes with thousands of objects with relatively little user interaction.", month = aug, journal = "ACM Transactions on Graphics", volume = "34", number = "4", issn = "0730-0301", doi = "10.1145/2766933", pages = "108:1--108:13", keywords = "modeling by example, complex model generation", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/guerrero-2015-lsp/", } @article{fan-2014-scfl, title = "Structure Completion for Facade Layouts", author = "Lubin Fan and Przemyslaw Musialski and Ligang Liu and Peter Wonka", year = "2014", abstract = "We present a method to complete missing structures in facade layouts. Starting from an abstraction of the partially observed layout as a set of shapes, we can propose one or multiple possible completed layouts. Structure completion with large missing parts is an ill-posed problem. Therefore, we combine two sources of information to derive our solution: the observed shapes and a database of complete layouts. The problem is also very difficult, because shape positions and attributes have to be estimated jointly. Our proposed solution is to break the problem into two components: a statistical model to evaluate layouts and a planning algorithm to generate candidate layouts. This ensures that the completed result is consistent with the observation and the layouts in the database.", month = nov, journal = "ACM Transactions on Graphics (ACM SIGGRAPH Asia 2014)", volume = "33", number = "6", pages = "210:1--210:11", keywords = "facade modeling, facade completion, structure completion, urban modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/fan-2014-scfl/", } @article{birsak-2014-agtb, title = "Automatic Generation of Tourist Brochures", author = "Michael Birsak and Przemyslaw Musialski and Peter Wonka and Michael Wimmer", year = "2014", abstract = "We present a novel framework for the automatic generation of tourist brochures that include routing instructions and additional information presented in the form of so-called detail lenses. The first contribution of this paper is the automatic creation of layouts for the brochures. Our approach is based on the minimization of an energy function that combines multiple goals: positioning of the lenses as close as possible to the corresponding region shown in an overview map, keeping the number of lenses low, and an efficient numbering of the lenses. The second contribution is a route-aware simplification of the graph of streets used for traveling between the points of interest (POIs). This is done by reducing the graph consisting of all shortest paths through the minimization of an energy function. The output is a subset of street segments that enable traveling between all the POIs without considerable detours, while at the same time guaranteeing a clutter-free visualization. Video: http://www.youtube.com/watch?v=t3w7uxzSR-Y", month = apr, journal = "Computer Graphics Forum (Proceedings of EUROGRAPHICS 2014)", volume = "33", number = "2", issn = "1467-8659", pages = "449--458", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/birsak-2014-agtb/", } @article{Guerrero-2014-GRF, title = "Edit Propagation using Geometric Relationship Functions", author = "Paul Guerrero and Stefan Jeschke and Michael Wimmer and Peter Wonka", year = "2014", abstract = "We propose a method for propagating edit operations in 2D vector graphics, based on geometric relationship functions. These functions quantify the geometric relationship of a point to a polygon, such as the distance to the boundary or the direction to the closest corner vertex. The level sets of the relationship functions describe points with the same relationship to a polygon. For a given query point we ?rst determine a set of relationships to local features, construct all level sets for these relationships and accumulate them. The maxima of the resulting distribution are points with similar geometric relationships. We show extensions to handle mirror symmetries, and discuss the use of relationship functions as local coordinate systems. Our method can be applied for example to interactive ?oor-plan editing, and is especially useful for large layouts, where individual edits would be cumbersome. We demonstrate populating 2D layouts with tens to hundreds of objects by propagating relatively few edit operations.", month = mar, journal = "ACM Transactions on Graphics", volume = "33", number = "2", issn = "0730-0301", doi = "10.1145/2591010", pages = "15:1--15:15", keywords = "Shape Modeling, Floor Plans, Edit Propagation, Geometric Relationship Functions", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/Guerrero-2014-GRF/", } @article{musialski-2013-surcgf, title = "A Survey of Urban Reconstruction", author = "Przemyslaw Musialski and Peter Wonka and Daniel G. Aliaga and Michael Wimmer and Luc van Gool and Werner Purgathofer", year = "2013", abstract = "This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under very active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision, and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved.", month = sep, issn = "1467-8659", journal = "Computer Graphics Forum", number = "6", volume = "32", pages = "146--177", keywords = "facade modeling, state-of-the-art report, multi-view stereo, structure from motion, urban modeling, urban reconstruction, inverse-procedural modeling, facade reconstruction", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/musialski-2013-surcgf/", } @article{musialski_2012_fice, title = "A Framework for Interactive Image Color Editing", author = "Przemyslaw Musialski and Ming Cui and Jieping Ye and Anshuman Razdan and Peter Wonka", year = "2012", abstract = "We propose a new method for interactive image color replacement that creates smooth and naturally looking results with minimal user interaction. Our system expects as input a source image and rawly scribbled target color values and generates high quality results in interactive rates. To achieve this goal we introduce an algorithm that preserves pairwise distances of the signatures in the original image and simultaneously maps the color to the user defined target values. We propose efficient sub-sampling in order to reduce the computational load and adapt semi-supervised locally linear embedding to optimize the constraints in one objective function. We show the application of the algorithm on typical photographs and compare the results to other color replacement methods.", month = nov, journal = "The Visual Computer", number = "11", volume = "29", pages = "1173--1186", keywords = "interactive image editing, color manipulation, image processing, recoloring, computational photography", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/musialski_2012_fice/", } @inproceedings{musialski-2012-sur, title = "A Survey of Urban Reconstruction", author = "Przemyslaw Musialski and Peter Wonka and Daniel G. Aliaga and Michael Wimmer and Luc van Gool and Werner Purgathofer", year = "2012", abstract = "This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under very active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision, and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved. ", month = may, booktitle = "EUROGRAPHICS 2012 State of the Art Reports", location = "Cagliari, Sardinia, Italy", publisher = "Eurographics Association", series = "EG STARs", pages = "1--28", keywords = "facade modeling, structure from motion, multi-view stereo, urban reconstruction, inverse-procedural modeling, urban modeling, image-based modeling, city reconstruction, state-of-the-art report", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/musialski-2012-sur/", } @article{musialski-2012-icb, title = "Interactive Coherence-Based Fa\c{c}ade Modeling", author = "Przemyslaw Musialski and Michael Wimmer and Peter Wonka", year = "2012", abstract = "We propose a novel interactive framework for modeling building fa\c{c}ades from images. Our method is based on the notion of coherence-based editing which allows exploiting partial symmetries across the fa\c{c}ade at any level of detail. The proposed workflow mixes manual interaction with automatic splitting and grouping operations based on unsupervised cluster analysis. In contrast to previous work, our approach leads to detailed 3d geometric models with up to several thousand regions per fa\c{c}ade. We compare our modeling scheme to others and evaluate our approach in a user study with an experienced user and several novice users.", month = may, journal = "Computer Graphics Forum (Proceedings of EUROGRAPHICS 2012)", volume = "31", number = "2", pages = "661--670", keywords = "facade modeling, urban modeling, facade reconstruction, image-based modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/musialski-2012-icb/", } @article{liu-2012-tcvd, title = "Tensor Completion for Estimating Missing Values in Visual Data", author = "Ji Liu and Przemyslaw Musialski and Peter Wonka and Jieping Ye", year = "2012", abstract = "In this paper we propose an algorithm to estimate missing values in tensors of visual data. Our methodology is built on recent studies about matrix completion using the matrix trace norm. The contribution of our paper is to extend the matrix case to the tensor case by proposing the first definition of the trace norm for tensors and then by building a working algorithm. First, we propose a definition for the tensor trace norm, that generalizes the established definition of the matrix trace norm. Second, similar to matrix completion, the tensor completion is formulated as a convex optimization problem. We developed three algorithms: SiLRTC, FaLRTC, and HaLRTC. The SiLRTC algorithm is simple to implement and employs a relaxation technique to separate the dependant relationships and uses the block coordinate descent (BCD) method to achieve a globally optimal solution; The FaLRTC algorithm utilizes a smoothing scheme to transform the original nonsmooth problem into a smooth one; The HaLRTC algorithm applies the alternating direction method of multipliers (ADMM) to our problem. Our experiments show potential applications of our algorithms and the quantitative evaluation indicates that our methods are more accurate and robust than heuristic approaches.", month = jan, issn = "0162-8828", journal = "IEEE Transactions on Pattern Analysis & Machine Intelligence (PAMI)", number = "1", volume = "35", pages = "208--220", keywords = "matrix completion, trace norm, tensor completion", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/liu-2012-tcvd/", } @article{jeschke-2011-est, title = "Estimating Color and Texture Parameters for Vector Graphics", author = "Stefan Jeschke and David Cline and Peter Wonka", year = "2011", abstract = "Diffusion curves are a powerful vector graphic representation that stores an image as a set of 2D Bezier curves with colors defined on either side. These colors are diffused over the image plane, resulting in smooth color regions as well as sharp boundaries. In this paper, we introduce a new automatic diffusion curve coloring algorithm. We start by defining a geometric heuristic for the maximum density of color control points along the image curves. Following this, we present a new algorithm to set the colors of these points so that the resulting diffused image is as close as possible to a source image in a least squares sense. We compare our coloring solution to the existing one which fails for textured regions, small features, and inaccurately placed curves. The second contribution of the paper is to extend the diffusion curve representation to include texture details based on Gabor noise. Like the curves themselves, the defined texture is resolution independent, and represented compactly. We define methods to automatically make an initial guess for the noise texure, and we provide intuitive manual controls to edit the parameters of the Gabor noise. Finally, we show that the diffusion curve representation itself extends to storing any number of attributes in an image, and we demonstrate this functionality with image stippling an hatching applications.", month = apr, journal = "Computer Graphics Forum", volume = "30", number = "2", note = "This paper won the 2nd best paper award at Eurographics 2011.", issn = "0167-7055", pages = "523--532", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/jeschke-2011-est/", } @article{lipp2011a, title = "Interactive Modeling of City Layouts using Layers of Procedural Content", author = "Markus Lipp and Daniel Scherzer and Peter Wonka and Michael Wimmer", year = "2011", abstract = "In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand-craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection-free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated. ", month = apr, journal = "Computer Graphics Forum (Proceedings EG 2011)", volume = "30", number = "2", issn = "0167-7055", pages = "345--354", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/lipp2011a/", } @article{LIPP-2010-PGMS, title = "Parallel Generation of Multiple L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2010", abstract = "This paper introduces a solution to compute L-systems on parallel architectures like GPUs and multi-core CPUs. Our solution can split the derivation of the L-system as well as the interpretation and geometry generation into thousands of threads running in parallel. We introduce a highly parallel algorithm for L-system evaluation that works on arbitrary L-systems, including parametric productions, context sensitive productions, stochastic production selection, and productions with side effects. This algorithm is further extended to allow evaluation of multiple independent L-systems in parallel. In contrast to previous work, we directly interpret the productions defined in plain-text, without requiring any compilation or transformation step (e.g., into shaders). Our algorithm is efficient in the sense that it requires no explicit inter-thread communication or atomic operations, and is thus completely lock free.", month = oct, issn = "0097-8493", journal = "Computers & Graphics", number = "5", volume = "34", pages = "585--593", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/LIPP-2010-PGMS/", } @inproceedings{musialski-2010-tof, title = "Tiling of Ortho-Rectified Fa\c{c}ade Images", author = "Przemyslaw Musialski and Meinrad Recheis and Stefan Maierhofer and Peter Wonka and Werner Purgathofer", year = "2010", abstract = "Typical building facades consist of regular structures such as windows arranged in a predominantly grid-like manner. We propose a method that handles precisely such facades and assumes that there must be horizontal and vertical repetitions of similar patterns. Using a Monte Carlo sampling approach, this method is able to segment repetitive patterns on orthogonal images along the axes even if the pattern is partially occluded. Additionally, it is very fast and can be used as a preprocessing step for finer segmentation stages.", month = may, isbn = "978-80-223-2644-5", publisher = "Comenius University, Bratislava", location = "Budmerice, Slovak Republic", editor = "Helwig Hauser , Reinhard Klein", booktitle = "Proceedings of 26th Spring Conference on Computer Graphics (SCCG 2010)", keywords = "image processing, facade segmentation, urban reconstruction", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/musialski-2010-tof/", } @article{jeschke-09-rendering, title = "Rendering Surface Details with Diffusion Curves", author = "Stefan Jeschke and David Cline and Peter Wonka", year = "2009", abstract = "Diffusion curve images (DCI) provide a powerful tool for efficient 2D image generation, storage and manipulation. A DCI consist of curves with colors defined on either side. By diffusing these colors over the image, the final result includes sharp boundaries along the curves with smoothly shaded regions between them. This paper extends the application of diffusion curves to render high quality surface details on 3D objects. The first extension is a view dependent warping technique that dynamically reallocates texture space so that object parts that appear large on screen get more texture for increased detail. The second extension is a dynamic feature embedding technique that retains crisp, anti-aliased curve details even in extreme closeups. The third extension is the application of dynamic feature embedding to displacement mapping and geometry images. Our results show high quality renderings of diffusion curve textures, displacements, and geometry images, all rendered interactively.", month = dec, journal = "Transaction on Graphics (Siggraph Asia 2009)", volume = "28", number = "5", issn = "0730-0301", booktitle = "Transactions on Graphics (Siggraph Asia 2009)", organization = "ACM", publisher = "ACM Press", pages = "1--8", keywords = "Geometry images, Displacement mapping, Diffusion curves, Line and Curve rendering ", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/jeschke-09-rendering/", } @article{jeschke-09-solver, title = "A GPU Laplacian Solver for Diffusion Curves and Poisson Image Editing", author = "Stefan Jeschke and David Cline and Peter Wonka", year = "2009", abstract = "We present a new Laplacian solver for minimal surfaces—surfaces having a mean curvature of zero everywhere except at some fixed (Dirichlet) boundary conditions. Our solution has two main contributions: First, we provide a robust rasterization technique to transform continuous boundary values (diffusion curves) to a discrete domain. Second, we define a variable stencil size diffusion solver that solves the minimal surface problem. We prove that the solver converges to the right solution, and demonstrate that it is at least as fast as commonly proposed multigrid solvers, but much simpler to implement. It also works for arbitrary image resolutions, as well as 8 bit data. We show examples of robust diffusion curve rendering where our curve rasterization and diffusion solver eliminate the strobing artifacts present in previous methods. We also show results for real-time seamless cloning and stitching of large image panoramas.", month = dec, journal = "Transaction on Graphics (Siggraph Asia 2009)", volume = "28", number = "5", issn = "0730-0301", booktitle = "Transactions on Graphics (Siggraph Asia 2009)", organization = "ACM", publisher = "ACM Press", pages = "1--8", keywords = "Poisson equation, Line and Curve rendering , Diffusion", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/jeschke-09-solver/", } @inproceedings{LIPP-2009-PGL, title = "Parallel Generation of L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2009", abstract = "This paper introduces a solution to compute L-systems on parallel architectures like GPUs and multi-core CPUs. Our solution can split the derivation of the L-system as well as the interpretation and geometry generation into thousands of threads running in parallel. We introduce a highly parallel algorithm for L-system evaluation that works on arbitrary L-systems, including parametric productions, context sensitive productions, stochastic production selection, and productions with side effects. Further we directly interpret the productions defined in plain-text, without requiring any compilation or transformation step (e.g., into shaders). Our algorithm is efficient in the sense that it requires no explicit inter-thread communication or atomic operations, and is thus completely lock free.", month = nov, isbn = "978-3980487481", location = "Braunschweig", editor = "Marcus Magnor, Bodo Rosenhahn, Holger Theisel", booktitle = "Vision, Modeling, and Visualization Workshop (VMV) 2009 ", pages = "205--214", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/LIPP-2009-PGL/", } @inproceedings{musialski-2009-sbfr, title = "Symmetry-Based Facade Repair", author = "Przemyslaw Musialski and Peter Wonka and Meinrad Recheis and Stefan Maierhofer and Werner Purgathofer", year = "2009", abstract = "In this paper we address the problem of removing unwanted image content in a single orthographic facade image. We exploit the regular structure present in building facades and introduce propagation process that is guided by the symmetry prevalent in the image. It removes larger unwanted image objects such as traffic lights, street signs, or cables as well as smaller noise, such as reflections in the windows. The output is intended as source for textures in urban reconstruction projects.", month = nov, isbn = "978-3980487481", location = "Braunschweig", editor = "Marcus Magnor, Bodo Rosenhahn, Holger Theisel ", booktitle = "Vision, Modeling, and Visualization Workshop 2009", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/musialski-2009-sbfr/", } @article{BITTNER-2009-AGVS, title = "Adaptive Global Visibility Sampling", author = "Jir\'{i} Bittner and Oliver Mattausch and Peter Wonka and Vlastimil Havran and Michael Wimmer", year = "2009", abstract = "In this paper we propose a global visibility algorithm which computes from-region visibility for all view cells simultaneously in a progressive manner. We cast rays to sample visibility interactions and use the information carried by a ray for all view cells it intersects. The main contribution of the paper is a set of adaptive sampling strategies based on ray mutations that exploit the spatial coherence of visibility. Our method achieves more than an order of magnitude speedup compared to per-view cell sampling. This provides a practical solution to visibility preprocessing and also enables a new type of interactive visibility analysis application, where it is possible to quickly inspect and modify a coarse global visibility solution that is constantly refined. ", month = aug, journal = "ACM Transactions on Graphics", volume = "28", number = "3", issn = "0730-0301", pages = "94:1--94:10", keywords = "occlusion culling, visibility sampling, visibility, PVS", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/BITTNER-2009-AGVS/", } @misc{LIPP-2009-PGL2, title = "Parallel Generation of L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2009", abstract = "In this work we investigate whether it is possible to efficiently evaluate one of the most classical procedural modeling primitives, L-systems, directly on parallel architectures, exemplified by current GPUs and multi-core CPUs. The main motivation is to enable interactive editing of large L-systems by designers, therefore it is important to speed up the computation of L-systems in order to achieve low response times.", month = aug, location = "New Orleans, LA", event = "High-Performance Graphics 2009", Conference date = "Poster presented at High-Performance Graphics 2009 (2009-08-01--2009-08-03)", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/LIPP-2009-PGL2/", } @article{cline-09-poisson, title = "Dart Throwing on Surfaces", author = "David Cline and Stefan Jeschke and Anshuman Razdan and Kenric White and Peter Wonka", year = "2009", abstract = "In this paper we present dart throwing algorithms to generate maximal Poisson disk point sets directly on 3D surfaces. We optimize dart throwing by efficiently excluding areas of the domain that are already covered by existing darts. In the case of triangle meshes, our algorithm shows dramatic speed improvement over comparable sampling methods. The simplicity of our basic algorithm naturally extends to the sampling of other surface types, including spheres, NURBS, subdivision surfaces, and implicits. We further extend the method to handle variable density points, and the placement of arbitrary ellipsoids without overlap. Finally, we demonstrate how to adapt our algorithm to work with geodesic instead of Euclidean distance. Applications for our method include fur modeling, the placement of mosaic tiles and polygon remeshing.", month = jun, journal = "Computer Graphics Forum", volume = "28", number = "4", pages = "1217--1226", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/cline-09-poisson/", } @article{Karnik-2010-routevis, title = "Route Visualization using Detail Lenses", author = "Pushpak Karnik and David Cline and Stefan Jeschke and Anshuman Razdan and Peter Wonka", year = "2009", abstract = "We present a method designed to address some limitations of typical route map displays of driving directions. The main goal of our system is to generate a printable version of a route map that shows the overview and detail views of the route within a single, consistent visual frame. Our proposed visualization provides a more intuitive spatial context than a simple list of turns. We present a novel multi-focus technique to achieve this goal, where the foci are defined by points-of-interest (POI) along the route. A detail lens that encapsulates the POI at a finer geospatial scale is created for each focus. The lenses are laid out on the map to avoid occlusion with the route and each other, and to optimally utilize the free space around the route. We define a set of layout metrics to evaluate the quality of a lens layout for a given route map visualization. We compare standard lens layout methods to our proposed method and demonstrate the effectiveness of our method in generating aesthetically pleasing layouts. Finally, we perform a user study to evaluate the effectiveness of our layout choices.", issn = "1077-2626", journal = "IEEE Transactions on Visualization and Computer Graphics", number = "2", volume = "16", pages = "235--247", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/Karnik-2010-routevis/", } @article{bhagvat-09-frusta, title = "GPU Rendering of Relief Mapped Conical Frusta", author = "Deepali Bhagvat and Stefan Jeschke and David Cline and Peter Wonka", year = "2009", abstract = "This paper proposes to use relief-mapped conical frusta (cones cut by planes) to skin skeletal objects. Based on this representation, current programmable graphics hardware can perform the rendering with only minimal communication between the CPU and GPU. A consistent definition of conical frusta including texture parametrization and a continuous surface normal is provided. Rendering is performed by analytical ray casting of the relief-mapped frusta directly on the GPU. We demonstrate both static and animated objects rendered using our technique and compare to polygonal renderings of similar quality.", issn = "0167-7055", journal = "Computer Graphics Forum", number = "28", volume = "8", pages = "2131--2139", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/bhagvat-09-frusta/", } @article{karnik-09-shapegrammar, title = "A Shape Grammar for Developing Glyph-based Visualizations", author = "Pushpak Karnik and Stefan Jeschke and David Cline and Anshuman Razdan and E. Wentz and Peter Wonka", year = "2009", abstract = "In this paper we address the question of how to quickly model glyph-based GIS visualizations. Our solution is based on using shape grammars to set up the different aspects of a visualization, including the geometric content of the visualization, methods for resolving layout conflicts and interaction methods. Our approach significantly increases modeling efficiency over similarly flexible systems currently in use.", issn = "0167-7055", journal = "Computer Graphics Forum", number = "8", volume = "28", pages = "2176--2188", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/karnik-09-shapegrammar/", } @article{LIPP-2008-IEV, title = "Interactive Visual Editing of Grammars for Procedural Architecture", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2008", abstract = "We introduce a real-time interactive visual editing paradigm for shape grammars, allowing the creation of rulebases from scratch without text file editing. In previous work, shape-grammar based procedural techniques were successfully applied to the creation of architectural models. However, those methods are text based, and may therefore be difficult to use for artists with little computer science background. Therefore the goal was to enable a visual workflow combining the power of shape grammars with traditional modeling techniques. We extend previous shape grammar approaches by providing direct and persistent local control over the generated instances, avoiding the combinatorial explosion of grammar rules for modifications that should not affect all instances. The resulting visual editor is flexible: All elements of a complex state-of-the-art grammar can be created and modified visually.", month = aug, journal = "ACM Transactions on Graphics", volume = "27", number = "3", note = "Article No. 102", issn = "0730-0301", doi = "10.1145/1360612.1360701", pages = "102:1--10", keywords = "procedural modeling, shape grammars, architectural modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/LIPP-2008-IEV/", } @inproceedings{MATTAUSCH-2007-OSP, title = "Optimized Subdivisions for Preprocessed Visibility", author = "Oliver Mattausch and Jir\'{i} Bittner and Peter Wonka and Michael Wimmer", year = "2007", abstract = "This paper describes a new tool for preprocessed visibility. It puts together view space and object space partitioning in order to control the render cost and memory cost of the visibility description generated by a visibility solver. The presented method progressively refines view space and object space subdivisions while minimizing the associated render and memory costs. Contrary to previous techniques, both subdivisions are driven by actual visibility information. We show that treating view space and object space together provides a powerful method for controlling the efficiency of the resulting visibility data structures.", month = may, isbn = "978-1-56881-337-0", publisher = "Canadian Human-Computer Communications Society", location = "Montreal, Canada", editor = "Christopher G. Healey and Edward Lank", booktitle = "Proceedings of Graphics Interface 2007", pages = "335--342", keywords = "visibility preprocessing, potentially visible sets, view cells", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/MATTAUSCH-2007-OSP/", } @article{WONKA-2006-GVS, title = "Guided Visibility Sampling", author = "Peter Wonka and Michael Wimmer and Kaichi Zhou and Stefan Maierhofer and Gerd Hesina and Alexander Reshetov", year = "2006", abstract = "This paper addresses the problem of computing the triangles visible from a region in space. The proposed aggressive visibility solution is based on stochastic ray shooting and can take any triangular model as input. We do not rely on connectivity information, volumetric occluders, or the availability of large occluders, and can therefore process any given input scene. The proposed algorithm is practically memoryless, thereby alleviating the large memory consumption problems prevalent in several previous algorithms. The strategy of our algorithm is to use ray mutations in ray space to cast rays that are likely to sample new triangles. Our algorithm improves the sampling efficiency of previous work by over two orders of magnitude.", month = jul, journal = "ACM Transactions on Graphics", volume = "25", number = "3", note = "Proceedings ACM SIGGRAPH 2006", issn = "0730-0301", doi = "10.1145/1141911.1141914", pages = "494--502", keywords = "visibility, visibility sampling, occlusion culling, PVS", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/WONKA-2006-GVS/", } @inproceedings{bittner-2005-egsr, title = "Fast Exact From-Region Visibility in Urban Scenes", author = "Jir\'{i} Bittner and Peter Wonka and Michael Wimmer", year = "2005", abstract = "We present a fast exact from-region visibility algorithm for 2.5D urban scenes. The algorithm uses a hierarchical subdivision of line-space for identifying visibility interactions in a 2D footprint of the scene. Visibility in the remaining vertical dimension is resolved by testing for the existence of lines stabbing sequences of virtual portals. Our results show that exact analytic from-region visibility in urban scenes can be computed at times comparable or even superior to recent conservative methods. ", month = jun, isbn = "3-905673-23-1", publisher = "Eurographics Association", organization = "Eurographics", location = "Konstanz, Germany", editor = "Kavita Bala and Philip Dutr\'{e}", booktitle = "Rendering Techniques 2005 (Proceedings Eurographics Symposium on Rendering)", pages = "223--230", keywords = "real-time rendering, visibility", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/bittner-2005-egsr/", } @article{Bittner-2003-Vis, title = "Visibility in Computer Graphics", author = "Jir\'{i} Bittner and Peter Wonka", year = "2003", abstract = "Visibility computation is crucial for computer graphics from its very beginning. The first visibility algorithms in computer graphics aimed to determine visible surfaces in a synthesized image of a 3D scene. Nowadays there are many different visibility algorithms for various visibility problems. We propose a new taxonomy of visibility problems that is based on a classification according to the problem domain. We provide a broad overview of visibility problems and algorithms in computer graphics grouped by the proposed taxonomy. The paper surveys visible surface algorithms, visibility culling algorithms, visibility algorithms for shadow computation, global illumination, point-based and image-based rendering, and global visibility computations. Finally, we discuss common concepts of visibility algorithm design and several criteria for the classification of visibility algorithms.", month = sep, issn = "0265-8135", journal = "Environment and Planning B: Planning and Design", number = "5", volume = "30", pages = "729--756", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Bittner-2003-Vis/", } @article{Wonka-2003-Ins, title = "Instant Architecture", author = "Peter Wonka and Michael Wimmer and Fran\c{c}ois Sillion and William Ribarsky", year = "2003", abstract = "This paper presents a new method for the automatic modeling of architecture. Building designs are derived using split grammars, a new type of parametric set grammar based on the concept of shape. The paper also introduces an attribute matching system and a separate control grammar, which offer the flexibility required to model buildings using a large variety of different styles and design ideas. Through the adaptive nature of the design grammar used, the created building designs can either be generic or adhere closely to a specified goal, depending on the amount of data available.", month = jul, journal = "ACM Transaction on Graphics", volume = "22", number = "3", note = "Proceedings ACM SIGGRAPH 2003", issn = "0730-0301", doi = "10.1145/882262.882324", pages = "669--677", keywords = "architecture, shape grammars, urban environments, modeling, real-time simulation, building design", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Wonka-2003-Ins/", } @inproceedings{Wimmer-2003-RTE, title = "Rendering Time Estimation for Real-Time Rendering", author = "Michael Wimmer and Peter Wonka", year = "2003", abstract = "This paper addresses the problem of estimating the rendering time for a real-time simulation. We study different factors that contribute to the rendering time in order to develop a framework for rendering time estimation. Given a viewpoint (or view cell) and a list of potentially visible objects, we propose several algorithms that can give reasonable upper limits for the rendering time on consumer hardware. This paper also discusses several implementation issues and design choices that are necessary to make the rendering time predictable. Finally, we lay out two extensions to current rendering hardware which would allow implementing a system with constant frame rates.", month = jun, isbn = "3-905673-03-7", publisher = "Eurographics Association", organization = "Eurographics", location = "Leuven, Belgium", editor = "Per Christensen and Daniel Cohen-Or", booktitle = "Rendering Techniques 2003 (Proceedings Eurographics Symposium on Rendering)", pages = "118--129", keywords = "graphics hardware, real-time rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Wimmer-2003-RTE/", } @inproceedings{Bittner-2001-Vis, title = "Visibility Preprocessing for Urban Scenes using Line Space Subdivision", author = "Jir\'{i} Bittner and Peter Wonka and Michael Wimmer", year = "2001", abstract = "We present an algorithm for visibility preprocessing of urban environments. The algorithm uses a subdivision of line space to analytically calculate a conservative potentially visible set for a given region in the scene. We present a detailed evaluation of our method including a comparison to another recently published visibility preprocessing algorithm. To the best of our knowledge the proposed method is the first algorithm that scales to large scenes and efficiently handles large view cells.", month = oct, isbn = "0-7695-1227-5", publisher = "IEEE Computer Society Press", location = "Tokyo, Japan", editor = "Bob Werner", booktitle = "Proceedings of Pacific Graphics 2001 (Ninth Pacific Conference on Computer Graphics and Applications)", pages = "276--284", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Bittner-2001-Vis/", } @article{Wonka-2001-Ins, title = "Instant Visibility", author = "Peter Wonka and Michael Wimmer and Fran\c{c}ois Sillion", year = "2001", abstract = "We present an online occlusion culling system which computes visibility in parallel to the rendering pipeline. We show how to use point visibility algorithms to quickly calculate a tight potentially visible set (PVS) which is valid for several frames, by shrinking the occluders used in visibility calculations by an adequate amount. These visibility calculations can be performed on a visibility server, possibly a distinct computer communicating with the display host over a local network. The resulting system essentially combines the advantages of online visibility processing and region-based visibility calculations, allowing asynchronous processing of visibility and display operations. We analyze two different types of hardware-based point visibility algorithms and address the problem of bounded calculation time which is the basis for true real-time behavior. Our results show reliable, sustained 60 Hz performance in a walkthrough with an urban environment of nearly 2 million polygons, and a terrain flyover.", month = sep, journal = "Computer Graphics Forum", volume = "20", number = "3", note = "G\"{u}nther Enderle [Best Paper] Award, Best Student Paper Award. A. Chalmers and T.-M. Rhyne (eds.), Proceedings EUROGRAPHICS 2001", issn = "0167-7055", pages = "411--421", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Wonka-2001-Ins/", } @inproceedings{Wimmer-2001-Poi, title = "Point-Based Impostors for Real-Time Visualization", author = "Michael Wimmer and Peter Wonka and Fran\c{c}ois Sillion", year = "2001", abstract = "We present a new data structure for encoding the appearance of a geometric model as seen from a viewing region (view cell). This representation can be used in interactive or real-time visualization applications to replace a complex model by an impostor, maintaining high quality rendering while cutting down rendering time. Our approach relies on an object-space sampled representation similar to a point cloud or a layered depth image, but introduces two fundamental additions to previous techniques. First, the sampling rate is controlled to provide sufficient density across all possible viewing conditions from the specified view cell. Second, a correct, antialiased representation of the plenoptic function is computed using Monte Carlo integration. Our system therefore achieves high quality rendering using a simple representation with bounded complexity. We demonstrate the method for an application in urban visualization.", month = jun, isbn = "3-211-83709-4", publisher = "Springer-Verlag", organization = "Eurographics", editor = "Steven J. Gortler and Karol Myszkowski", booktitle = "Rendering Techniques 2001 (Proceedings Eurographics Workshop on Rendering)", pages = "163--176", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Wimmer-2001-Poi/", } @phdthesis{Wonka-thesis, title = "Occlusion Culling for Real-Time Rendering of Urban Environments", author = "Peter Wonka", year = "2001", 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/2001/Wonka-thesis/", } @inproceedings{wonka-2000-VisP, title = "Visibility Preprocessing with Occluder Fusion for Urban Walkthroughs", author = "Peter Wonka and Michael Wimmer and Dieter Schmalstieg", year = "2000", abstract = "This paper presents an efficient algorithm for occlusion culling of urban environments. It is conservative and accurate in finding all significant occlusion. It discretizes the scene into view cells, for which cell-to-object visibility is precomputed, making on-line overhead negligible. Unlike other precomputation methods for view cells, it is able to conservatively compute all forms of occluder interaction for an arbitrary number of occluders. To speed up preprocessing, standard graphics hardware is exploited and occluder occlusion is considered. A walkthrough application running an 8 million polygon model of the city of Vienna on consumer-level hardware illustrates our results.", month = jun, isbn = "3-211-83535-0", publisher = "Springer-Verlag Wien New York", organization = "Eurographics", location = "held in Brno, Czech Republic, June 26-28, 2000", editor = "Bernard P\'{e}roche and Holly Rushmeier", booktitle = "Rendering Techniques 2000 (Proceedings Eurographics Workshop on Rendering)", pages = "71--82", keywords = "Visibility determination, image-based rendering., occluder occlusion, occluder fusion, urban environments, walkthrough, real-time graphics, shadow algorithms, occlusion culling", URL = "https://www.cg.tuwien.ac.at/research/publications/2000/wonka-2000-VisP/", } @article{Wonka-1999-Occ, title = "Occluder Shadows for Fast Walkthroughs of Urban Environments.", author = "Peter Wonka and Dieter Schmalstieg", year = "1999", abstract = "This paper describes a new algorithm that employs image-based rendering for fast occlusion culling in complex urban environments. It exploits graphics hardware to render and automatically combine a relatively large set of occluders. The algorithm is fast to calculate and therefore also useful for scenes of moderate complexity and walkthroughs with over 20 frames per second. Occlusion is calculated dynamically and does not rely on any visibility precalculation or occluder preselection. Speed-ups of one order of magnitude can be obtained.", month = sep, journal = "Computer Graphics Forum", volume = "18", number = "3", issn = "1067-7055", pages = "51--60", URL = "https://www.cg.tuwien.ac.at/research/publications/1999/Wonka-1999-Occ/", } @misc{Wonka-1998-Ray, title = "Raytracing of nonlinear fractals", author = "Peter Wonka and Michael Gervautz", year = "1998", note = "WSCG Plzen 1998 Proceedings, pp. 424-431, 1998.", URL = "https://www.cg.tuwien.ac.at/research/publications/1998/Wonka-1998-Ray/", }