@article{wilkie-2009-cc, title = "A Robust Illumination Estimate for Chromatic Adaptation in Rendered Images", author = "Alexander Wilkie and Andrea Weidlich", year = "2009", abstract = "We propose a method that improves automatic colour correction operations for rendered images. In particular, we propose a robust technique for estimating the visible and pertinent illumination in a given scene. We do this at very low computational cost by mostly re-using information that is already being computed during the image synthesis process. Conventional illuminant estimations either operate only on 2D image data, or, if they do go beyond pure image analysis, only use information on the luminaires found in the scene. The latter is usually done with little or no regard for how the light sources actually affect the part of the scene that is being viewed. Our technique goes beyond that, and also takes object reflectance into account, as well as the incident light that is actually responsible for the colour of the objects that one sees. It is therefore able to cope with difficult cases, such as scenes with mixed illuminants, complex scenes with many light sources of varying colour, or strongly coloured indirect illumination. ", month = jun, journal = "Computer Graphics Forum", volume = "28", number = "4", pages = "1101--1109", keywords = "chromatic adaptation, predicitve rendering, colour constancy", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/wilkie-2009-cc/", } @article{weidlich-2009-dispersion, title = "Anomalous Dispersion in Predictive Rendering", author = "Andrea Weidlich and Alexander Wilkie", year = "2009", abstract = "In coloured media, the index of refraction does not decrease monotonically with increasing wavelength, but behaves in a quite non-monotonical way. This behaviour is called anomalous dispersion and results from the fact that the absorption of a material influences its index of refraction. So far, this interesting fact has not been widely acknowledged by the graphics community. In this paper, we demonstrate how to calculate the correct refractive index for a material based on its absorption spectrum with the Kramers-Kronig relation, and we discuss for which types of objects this effect is relevant in practice. ", month = jun, journal = "Computer Graphics Forum", volume = "28", number = "4", pages = "1065--1072", keywords = "Predictive rendering, Spectral Rendering, Dispersion", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/weidlich-2009-dispersion/", } @inproceedings{weidlich_2009_REL, title = "Rendering the Effect of Labradorescence", author = "Andrea Weidlich and Alexander Wilkie", year = "2009", abstract = "Labradorescence is a complex optical phenomenon that can be found in certain minerals, such as Labradorite or Spectrolite. Because of their unique colour properties these minerals are often used as gemstones and decorative objects. Since the phenomenon is strongly orientation dependent, such minerals need a special cut to make the most of their unique type of colourful sheen, which makes it desirable to be able to predict the final appearance of a given stone prior to the cutting process. Also, the peculiar properties of the effect make a believable replication with an ad-hoc shader dificult even for normal, non-predictive rendering purposes. We provide a reflectance model for labradorescence that is directly derived from the physical characteristics of such materials. Due to its inherent accuracy, it can be used for predictive rendering purposes, but also for generic rendering applications. ", month = may, isbn = "978-1-56881-470-4", publisher = "ACM", location = "Kelowna, British Columbia, Canada ", booktitle = "Proceedings of Graphics Interface 2009", pages = "79--85", keywords = "Predictive Rendering, Surface, Crystals", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/weidlich_2009_REL/", } @inproceedings{wilkie-209.pr, title = "Predictive Rendering", author = "Alexander Wilkie and Andrea Weidlich and Marcus Magnor and A. Chalmers", year = "2009", abstract = "This course intends to serve two closely related purposes: to provide an accurate definition of the term predictive rendering, the sub-discipline of computer graphics that attempts to provide reliable predictions of object appearance, and to present the technological foundations on which one can currently conduct research in this area. The first goal of the course – a clear definition of what predictive rendering actually is – seems to be necessary due to the extreme prevalence of its antonym, believable rendering. Practically all contemporary production computer graphics, as well as most current graphics research efforts, fall into the latter category. Coupled with the fact that in the collective mindset of the graphics community, the distinction between these areas has, for a variety of reasons, been somewhat blurry so far, a precise clarifying statement appears to be in order. The second, much larger and technical part of the course then presents the foundations of current predictive rendering. Unlike believable rendering, where any technology that delivers visually convincing (as opposed to radiometrically correct) results is acceptable for a given task, a predictive pipeline suffers from the fundamental problem that all components – modeling, rendering, display – have to be of a uniformly high quality to ensure a predictive result. This fact has, over time, no doubt served to deter many researchers from entering this promising and interesting field, in which a large amount of work still lies ahead of us. In the second part, we cover an entire predictive rendering pipeline, and for each stage present those – in some cases surprisingly few – graphics technologies that can be used in such a context. This course should enable anyone with a solid background in graphics to bootstrap a basic predictive rendering environment, with which further research, or perhaps even specialised production work, can be conducted.", booktitle = "SIGGRAPH Asia 2009 Courses", location = "Yokohama, Japan", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/wilkie-209.pr/", } @inproceedings{weidlich_2009_EPLBM, title = "Exploring the Potential of Layered BRDF Models", author = "Andrea Weidlich and Alexander Wilkie", year = "2009", abstract = "This course serves as a guide on the considerable potential of layered surface models. The key advantage of using such layered BRDFs over traditional, more general shading language constructs is that the end result is automatically highly physically plausible. In particular, we demonstrate on a simple layered surface model that combines several traditional BRDF components how a surprisingly large number of interesting and important surface types can be efficiently represented by using the same, not particularly complex, BRDF code. We also show how handy such an approach is for the eventual end user, whose main concern is the ease with which one can describe object appearance based only on a few intuitive parameters. We first discuss layered surface models in computer graphics and the constraints of modelling object appearance in a physically plausible fashion. We then demonstrate the techniques that can be used to efficiently evaluate layered BRDF models, give examples of the surface types that can be described in this way. We also go beyond plain surface models, and showcase how a texture-based combination of layered surface components can be used to describe highly complex object appearance attributes, while implicitly remaining physically plausible.", booktitle = "SIGGRAPH Asia 2009 Courses", location = "Yokohama, Japan", publisher = "webpage: http://portal.acm.org/citation.cfm?id=1665824", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/weidlich_2009_EPLBM/", } @inproceedings{weidlich_2008_magwpt, title = "Modeling Aventurescent Gems with Procedural Textures", author = "Andrea Weidlich and Alexander Wilkie", year = "2008", abstract = "In this paper we present the results of an investigation on how one can model aventurescence, an interesting and optically appealing property of some gemstones. Our goal was to find a method that is both efficient and reasonably realistic, and that can still be used in the context of a global illumination rendering system.", month = apr, publisher = "ACM", location = "Budmarice", booktitle = "Proceedings of the Spring Conference on Computer Graphics (SCCG)", keywords = "gemstone rendering, aventurescence, procedural textures", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/weidlich_2008_magwpt/", } @article{weidlich_2007_rrbuc, title = "Realistic Rendering of Birefringency in Uniaxial Crystals", author = "Andrea Weidlich and Alexander Wilkie", year = "2008", abstract = "In this paper we derive the complete set of formulas which is needed to generate physically plausible images of uniaxial crystals. So far no computer graphics publication contains all the formulas one needs to compute the interaction of light with such crystals in a form that is useable by a graphics application, especially if a polarisation-aware rendering system is being used. This paper contains the complete derivation of the Fresnel coefficients for birefringent transparent materials, as well as for the direction cosines of the extraordinary ray and the Mueller matrices necessary to describe polarisation effects. The formulas we derive can be directly used in a ray based renderer, and we demonstrate these capabilities in test scenes.", month = mar, journal = "ACM Transactions on Graphics", volume = "27", number = "1", pages = "6:1--6:12", keywords = "polarization, crystals, Birefringence", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/weidlich_2007_rrbuc/", } @inproceedings{weidlich_2007_almfs, title = "Arbitrarily Layered Micro-Facet Surfaces", author = "Andrea Weidlich and Alexander Wilkie", year = "2007", abstract = "In this paper we present a method to combine several micro-facet based surface layers into a single unified, expressive BRDF model that is easy to use. The restriction to micro-facet based layers constitutes no loss of generality, since both perfectly specular and perfectly diffuse surfaces can be seen as limit cases of the micro-facet approach. Such multi-layered surfaces can be used to re-create the appearance of a wide range of different materials, and yield good results without having to perform explicit sub–surface scattering computations. This is achieved through suitable approximations and simplifications of the scattering within the simulated layered surface, while still taking absorption and total internal reflection into account. We also discuss the corresponding probability distribution function that is needed for sampling purposes, and investigate how the flexibility of this new approach is best put to use. ", month = dec, isbn = "978-1-59593-912-8", publisher = "ACM", location = "Perth, Australia", booktitle = "GRAPHITE 2007", pages = "171--178", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/weidlich_2007_almfs/", } @inproceedings{zotti-2007-wscg, title = "A Critical Review of the Preetham Skylight Model", author = "Georg Zotti and Alexander Wilkie and Werner Purgathofer", year = "2007", abstract = "The Preetham skylight model is currently one of the most widely used analytic models of skylight luminance in computer graphics. Despite its widespread use, very little work has been carried out to verify the results generated by the model, both in terms of the luminance patterns it generates, and in terms of numerical reliability and stability. We have implemented the model in Mathematica, visualise and discuss those parameter ranges which exhibit problematic behaviour, and compare the computed luminance values with references from literature, especially the 15 standard skylight distributions of the CIE 2003 Standard General Sky. We also performed luminance measurements on real cloudless skies, and compare these measurements to the predictions of the model.", month = jan, isbn = "978-80-86943-02-2", publisher = "University of West Bohemia", location = "Plzen", editor = "Vaclav Skala", booktitle = "WSCG ", pages = "23--30", keywords = "Verification, Skylight", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/zotti-2007-wscg/", } @inproceedings{wilkie-2006-dfs, title = "A Reflectance Model for Diffuse Fluorescent Surfaces", author = "Alexander Wilkie and Andrea Weidlich and Caroline Larboulette and Werner Purgathofer", year = "2006", abstract = "Fluorescence is an interesting and visually prominent effect, which has not been fully covered by Computer Graphics research so far. While the physical phenomenon of fluorescence has been addressed in isolation, the actual reflection behaviour of real fluorescent surfaces has never been documented, and no analytical BRDF models for such surfaces have been published yet. This paper aims to illustrate the reflection properties typical for diffuse fluorescent surfaces, and provides a BRDF model based on a layered microfacet approach that mimics them.", month = nov, isbn = "1-59593-564-9", location = "Kuala Lumpur, Malaysia", booktitle = "Proceedings of Graphite 2006", pages = "8", pages = "321--328", keywords = "Fluorescence, Analytical BRDF models", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/wilkie-2006-dfs/", } @inproceedings{zotti-2006-pla, title = "Using Virtual Reconstructions in a Planetarium for Demonstrations in Archaeo-Astronomy", author = "Georg Zotti and Alexander Wilkie and Werner Purgathofer", year = "2006", abstract = "In the last decades, archaeologists in central Europe have found traces of enigmatic neolithic circular building structures buried in the soil. Recent studies indicate that the orientation of many of their doorways may have been chosen with an astronomical background in mind. This paper explains the use of virtual reconstructions of these buildings from archaeological data, in combination with a simulation of the sky of that time in a Planetarium, to present the astronomical findings to the public.", month = nov, isbn = "963-9495-89-1", publisher = "Pannonian University Press", location = "Eger", editor = "Cecilia Sik Lanyi ", booktitle = "Third Central European Multimedia and Virtual Reality Conference (Proc. CEMVRC2006)", pages = "43--51", keywords = "Virtual Reality, Public Dissemination, Archaeo-Astronomy", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/zotti-2006-pla/", } @article{ulbricht-2006-VOP, title = "Verification of Physically Based Rendering Algorithms", author = "Christiane Ulbricht and Alexander Wilkie and Werner Purgathofer", year = "2006", abstract = "Within computer graphics, the field of predictive rendering is concerned with those methods of image synthesis which yield results that do not only look real, but are also radiometrically correct renditions of nature, i.e.which are accurate predictions of what a real scene would look like under given lighting conditions. In order to guarantee the correctness of the results obtained by such techniques, three stages of such a rendering system have to be verified with particular care: the light reflection models, the light transport simulation and the perceptually based calculations used at display time. In this report, we will concentrate on the state of the art with respect to the second step in this chain. Various approaches for experimental verification of the implementation of a physically based rendering system have been proposed so far. However, the problem of proving that the results are correct is not fully solved yet, and no standardized methodology is available. We give an overview of existing literature, discuss the strengths and weaknesses of the described methods and illustrate the unsolved problems. We also briefly discuss the related issue of image quality metrics. ", month = jun, issn = "0167-7055", journal = "Computer Graphics Forum", number = "2", volume = "25", pages = "237--255", keywords = "visual comparisons, experimental validation, test scenes, physically based rendering, image quality metrics", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/ulbricht-2006-VOP/", } @incollection{PURGATHOFER-2006-IHB, title = "Grafische Datenverarbeitung", author = "Werner Purgathofer and Michael Wimmer and Alexander Wilkie", year = "2006", abstract = "Die grafische Datenverarbeitung oder Computergrafik umfa{\ss}t im weitesten Sinn alle Methoden und Techniken, bei denen mit dem Computer Bilder und Bildinformationen erstellt oder verarbeitet werden.", address = "Munich", booktitle = "Informatik Handbuch (4th Edition)", editor = "Peter Rechenberg and Gustav Pomberger", isbn = "3-446-40185-7", publisher = "Carl Hanser Verlag", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/PURGATHOFER-2006-IHB/", } @inproceedings{ulbricht-2006apw, title = "A Problem with the Use of XYZ Colour Space for Photorealistic Rendering Computations", author = "Christiane Ulbricht and Alexander Wilkie", year = "2006", abstract = "CIE XYZ colour space is sometimes recommended in literature for photorealistic rendering computations because it allows one to simultaneously handle all perceivable colours at much lower computational cost than by using spectral rendering. In this paper we show that XYZ is actually a poor choice for such computations, since it is not closed under the component-wise multiplication which is a typical operation in a rendering system. We also discuss why this rather obvious fact has not received much attention yet, and give pointers to alternative solutions.", publisher = "CGIV", booktitle = "Third European Conference on Colour in Graphics, Imaging, and Vision", pages = "435--437", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/ulbricht-2006apw/", } @inproceedings{wilkie-2005-sco, title = "Spectral Colour Order Systems and Appearance Metrics for Fluorescent Solid Colours", author = "Alexander Wilkie and Caroline Larboulette and Werner Purgathofer", year = "2005", abstract = "One aspect of Computational Aesthetics is the finding of harmonic colours for the objects in a scene. Although the obtained degree of colour harmony is a subjective criterion, experience shows that on average human observers tend to have quite similar responses to individual colour stimuli and their combinations. This observation is the basis for what is commonly referred to as Colour Order Systems (COS), which aim to arrange colours in a fashion such that users can intuitively select individual colours – or even whole sets of them – according to some criterion. However, when dealing with a spectral rendering system, the use of traditional colour space COS to obtain pleasant associations of colours becomes impossible, principally due to metamerism. An interesting problem would be the derivation of a COS for spectral data which includes the ability to deal with fluorescent colours, the indirect goal of such a metric system being the selection of aesthetically pleasing colour values for a spectral renderer. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism: Color", month = may, location = "Girona, Spain", editor = "L. Neumann, M. Sbert, B. Gooch, W. Purgathofer", booktitle = "Proceedings of Computational Aesthetics in Graphics, Visualization and Imaging", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/wilkie-2005-sco/", } @inproceedings{ulbricht-2005-VOP, title = "Verification of Physically Based Rendering Algorithms", author = "Christiane Ulbricht and Alexander Wilkie and Werner Purgathofer", year = "2005", abstract = "Within computer graphics, the field of predictive rendering is concerned with those methods of image synthesis which yield results that do not only look real, but are also radiometrically correct renditions of nature, i.e. which are accurate predictions of what a real scene would look like under given lighting conditions. In order to guarantee the correctness of the results obtained by such techniques, three stages of such a rendering system have to be verified with particular care: the light reflection models, the light transport simulation and the perceptually based calculations used at display time. In this report, we will concentrate on the state of the art with respect to the second step in this chain. Various approaches for experimental verification of the implementation of a physically based rendering system have been proposed so far. However, the problem of proving that the results are correct is not fully solved yet, and no standardized methodology is available. We give an overview of existing literature, discuss the strengths and weaknesses of the described methods and illustrate the unsolved problems. We also briefly discuss the related issue of image quality metrics. ", booktitle = "State of the Art Reports, Eurographics 05", publisher = "The Eurographics Association, and The Image Synthesis Group", pages = "95--112", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/ulbricht-2005-VOP/", } @inproceedings{Wilkie-2004-AMS, title = "An Analytical Model for Skylight Polarisation", author = "Alexander Wilkie and Robert F. Tobler and Christiane Ulbricht and Georg Zotti and Werner Purgathofer", year = "2004", abstract = "Under certain circumstances the polarisation state of the illumination can have a significant influence on the appearance of scenes; outdoor scenes with specular surfaces -- such as water bodies or windows -- under clear, blue skies are good examples of such environments. In cases like that it can be essential to use a polarising renderer if a true prediction of nature is intended, but so far no polarising skylight models have been presented. This paper presents a plausible analytical model for the polarisation of the light emitted from a clear sky. Our approach is based on a suitable combination of several components with well-known characteristics, and yields acceptable results in considerably less time than an exhaustive simulation of the underlying atmospheric scattering phenomena would require.", month = jun, isbn = "3-905673-12-6", publisher = "?", editor = "Alexander Keller and Henrik Wann Jensen ", booktitle = "Proceedings of the Eurographics Symposium on Rendering", pages = "387--399", keywords = "skylight rendering, polarisation", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/Wilkie-2004-AMS/", } @misc{meseth-2004-hqr, title = "High Quality Rendering of Reflectance Data", author = "Jan Meseth and Gero M\"{u}ller and Mirko Sattler and Ralf Sarlette and Alessandro Artusi and Alexander Wilkie and Georg Zotti and Klein Reinhard and Werner Purgathofer", year = "2004", abstract = "The tutorial will introduce the basic terminology, show techniques for acquisition of reflectance properties of both synthetic and real-world materials, present common representations for reflectance properties and will elaborate on rendering techniques both for real-time and offline applications. While the tutorial gives an overview over existing techniques for most aspects, selected topics will be described in much more detail. In addition to describing acquisition, storage and rendering of reflectance properties, related areas will be covered. In fact, texturing and parameterization, texture- and BTF synthesis and tone mapping represent techniques which are inevitable to achieve really photorealistic results and are therefore required by every system that aims at using reflectance properties. Here, as well, an overview over the research areas will be given, existing techniques will de described and selected topics will be elaborated on in more detail. ", note = "Tutorial auf CGI 2004", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/meseth-2004-hqr/", } @article{Artusi-2003-Col, title = "Novel Colour Printer Characterization Model", author = "Alessandro Artusi and Alexander Wilkie", year = "2003", abstract = "A key problem in multimedia systems is the faithful reproduction of color. One of the main reasons why this is a complicated issue are the different color reproduction technologies used by the various devices; displays use easily modeled additive color mixing, while printers use a subtractive process, the characterization of which is much more complex than that of self--luminous displays. In order to resolve these problems several processing steps are necessary, one of which is accurate device characterization. Our study examines different learning algorithms for one particular neural network technique which already has been found to be useful in related contexts -- namely radial basis function network models -- and proposes a modified learning algorithm which improves the colorimetric characterization process of printers. In particular our results show that is possible to obtain good performance by using a learning algorithm that is trained on only small sets of color samples, and use it to generate a larger look--up table (LUT) through use of multiple polynomial regression or an interpolation algorithm. We deem our findings to be a good start point for further studies on learning algorithms used in conjunction with this problem.", month = jul, issn = "1017-9909", journal = "Journal of Electronic Imaging", number = "3", volume = "12", pages = "448--458", keywords = "neural network, Colorimetric characterization, Radial basis function", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Artusi-2003-Col/", } @inproceedings{Artusi-2003-Del, title = "Delivering Interactivity to Complex Tone Mapping Operators", author = "Alessandro Artusi and Jir\'{i} Bittner and Michael Wimmer and Alexander Wilkie", year = "2003", abstract = "The accurate display of high dynamic range images requires the application of complex tone mapping operators. These operators are computationally costly, which prevents their usage in interactive applications. We propose a general framework that delivers interactive performance to an important subclass of tone mapping operators, namely global tone mapping operators. The proposed framework consists of four steps: sampling the input image, applying the tone mapping operator, tting the point-sampled tone mapping curve, and reconstructing the tone mapping curve for all pixels of the input image. We show how to make use of recent graphics hardware while keeping the advantage of generality by performing tone mapping in software. We demonstrate the capabilities of our method by accelerating several common global tone mapping operators and integrating the operators in a real-time rendering application.", 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 = "38--44", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/Artusi-2003-Del/", } @xmascard{xmas-2003, title = "X-Mas 2003", author = "Werner Purgathofer and Alexander Wilkie", year = "2003", abstract = "25 Jahre Computergraphik an der TU Wien Geschichte ist eng mit Personen verbunden. Die Geschichte der Computergraphik an der Technischen Universit\"{a}t Wien begann unabh\"{a}ngig voneinander an zwei Instituten. In beiden F\"{a}llen entstanden die ersten Diplomarbeiten im Jahr 1978. Eine Initiative begann mit Johann Wei{\ss}, der sich mit dem Tracken von Lichtstiften besch\"{a}ftigte, und Georg Stonawski, der eine Diplomarbeit \"{u}ber GKS schrieb. Die zweite Initiative kam von Prof. Wilhelm Barth, der die zwei Diplomanden Emanuel Wenger und Edwin Scherzer die Programmiersprache Pascal um graphische Elemente erweitern lie{\ss}. Im Jahr 1980 begann Werner Purgathofer zusammen mit einigen anderen bei Prof. Barth als Assistent und schloss 1984 seine Dissertation ab. Anschlie{\ss}end baute er zusammen mit Michael Gervautz und anderen eine Computergraphik-Arbeitsgruppe auf, die haupts\"{a}chlich im Bereich Rendering aktiv war. Als Werner Purgathofer 1988 Professor wurde, stellte er M. Eduard Gr\"{o}ller ein, der die Arbeitsgruppe f\"{u}r Visualisierung gr\"{u}ndete. 1990 wurde das Institut in "Institut f\"{u}r Computergraphik" umbenannt, 1991 organisierte die Gruppe die Jahrestagung der Eurographics in der Wiener Hofburg. Bald danach begann Michael Gervautz im Bereich Virtual Reality zu forschen, woraufhin er 1998 die Spinoff-Firma "Imagination" gr\"{u}ndete und Dieter Schmalstieg die Leitung der Virtual Reality-Gruppe \"{u}bernahm. Anfang 2000 gr\"{u}ndete das Institut zusammen mit anderen ein Kompetenzzentrum f\"{u}r Virtual Reality und Visualisierung (VRVis), in dem jetzt Georg Stonawski Gesch\"{a}ftsf\"{u}hrer und Helwig Hauser wissenschaftlicher Direktor sind. Nach diesen 25 Jahren arbeiten heute in Wien mehr als 100 Personen im Bereich innovativer Computergraphik. Die Karte wurde unter Verwendung von Adobe Illustrator und Photoshop auf einem Apple iBook produziert. F\"{u}r die Farbkalibration des bei der Herstellung der physischen Karten verwendeten Druckers wurde die Software ProfileMaker von Gretag Macbeth verwendet. Idee: Werner Purgathofer Bilder: Der Meister, Emanuel Wenger, Michael Gervautz, Robert F. Tobler, Michael Feda, Christoph Traxler, Michael Wimmer, Alexander Wilkie, Helwig Hauser, Anton L. Fuhrmann und das Kollektiv der Visualisierungsgruppe Herstellung: Alexander Wilkie 25 Years of Computer Graphics at the TU Vienna History is strongly connected to people. The history of Computer Graphics at the Vienna University of Technology began independently at two institutes. In both cases the first diploma theses were written in 1978. One initiative was started by Johann Weiss, who implemented the tracking of a light pen, and Georg Stonawski, who wrote a thesis about GKS. The second initiative was by Prof. Wilhelm Barth, who worked with the two diploma students Emanuel Wenger and Edwin Scherzer on extending the programming language Pascal with graphical elements. Amongst others, Werner Purgathofer started to work as an assistant of Prof. Barth in 1980, and finished his PhD in 1984. Together with Michael Gervautz and other colleagues, he then built up a Computer Graphics group that was active mainly in the area of Rendering. When Werner Purgathofer became Professor in 1988, he employed M. Eduard Gr\"{o}ller, who in turn founded a Visualisation research group. In 1990 the institute was renamed to "Institute of Computer Graphics", in 1991 the group organized the annual Eurographics conference in the Vienna Hofburg. Soon after that, Michael Gervautz started research in the area of Virtual Reality, which led to the founding of the spin-off company "Imagination" in 1998. Since then, the Virtual Reality group was led by Dieter Schmalstieg. Together with others, the institute created a competence center for Virtual Reality and Visualisation (VRVis) in January 2000, of which Georg Stonawski is the CEO and Helwig Hauser is the scientific director. After these 25 years, there are now more than 100 people in Vienna working in the field of innovative Computer Graphics. The card was produced using Adobe Illustrator and Photoshop on an Apple iBook. The colour calibration of the printer used for the production of the pysical cards was performed using Gretag Macbeth ProfileMaker software. Idea: Werner Purgathofer Images by: The Master, Emanuel Wenger, Michael Gervautz, Robert F. Tobler, Michael Feda, Christoph Traxler, Michael Wimmer, Alexander Wilkie, Helwig Hauser, Anton L. Fuhrmann and the collective of the Visualisation group Production: Alexander Wilkie ", URL = "https://www.cg.tuwien.ac.at/research/publications/2003/xmas-2003/", } @techreport{Artusi-2002-NRE, title = "New Realistic Tone mapping Algorithm", author = "Alessandro Artusi and Alexander Wilkie", year = "2002", abstract = "To properly reproduce a highy dynamic range image on a graphic display system is a harder problem than is commonly acknowledged. The last years have seen great progress in this area, and for non-interactive tone mapping problems adequate levels of realism have already been demonstrated, namely through the multiscale model of adaptation of Pattanaik et al.. Unfortunately, the high computational cost of their methods has so far precluded their use for the purposes of real-time rendering, and they have also been confined to single images without a temporal dependency. Conversely, the work of Tumblin et al. have demonstrated time dependency and interactivity for tone mapping techniques, but at the cost of significantly reduced realism. In this report we present a new high-quality time-dependent tone mapping algorithm which is comparable to the work of Pattanaik et al. in terms of visual realism, and demonstrate its viability on a number of test scenes.", month = feb, number = "TR-186-2-02-03", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "Human Visual system, Color sensitivity, Visual acuity, Glare, Time-Dependency", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Artusi-2002-NRE/", } @techreport{Artusi-2002-NRT, title = "New Real-Time Tone mapping Algorithm", author = "Alessandro Artusi and Alexander Wilkie", year = "2002", abstract = "The conversion from real-world to display luminance is known as tone-mapping, and the goals of the so-called tone mapping operator are to reproduce visibility and the overall impression of brightness, contrast and color. To truly realize this means to employ a very complex algorithm that exactly simulates how the human visual system is working. Due to its complexity, such a simulation cannot be used inside a real-time application. This means that realistic tone mapping models so far could not be used in interactive rendering applications, and that one had to resort to simpler, less convincing techniques in this case. We demostrate a new approach with which it is finally possible to use a realistic tone mapping model in a real time.", month = jan, number = "TR-186-2-02-02", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "Texture Mapping, Rendering Systems, Reflectance & Shading Models, Image-Based Rendering, Graphics Systems, Computer Vision, Color", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Artusi-2002-NRT/", } @inproceedings{Devlin-2002-STA, title = "STAR Report on Tone Reproduction and Physically Based Spectral Rendering", author = "K. Devlin and A. Chalmers and Alexander Wilkie and Werner Purgathofer", year = "2002", booktitle = "Eurographics 2002", publisher = "Eurographics Association", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/Devlin-2002-STA/", } @inproceedings{tobler02_amrmg, title = "A Multiresolution Mesh Generation Approach for Procedural Definition of Complex Geometry", author = "Robert F. Tobler and Stefan Maierhofer and Alexander Wilkie", year = "2002", isbn = "0-7695-1546-0", publisher = "IEEE", location = "Banff, Alberta, Canada", booktitle = "Shape Modeling International 2002", pages = "35--42", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/tobler02_amrmg/", } @xmascard{xmas-2002, title = "X-Mas 2002", author = "Georg Zotti and Attila Neumann and Alexander Wilkie", year = "2002", abstract = "Der Blick auf Wien wurde Hartmann Schedels Weltchronik (1493) entnommen. Das Motiv "Die K\"{o}nige folgen dem Stern" findet sich im Atlas Catalan der Biblioth\`{e}que Nationale de France (14. Jahrhundert). Es wurde f\"{u}r die Karte etwas \"{u}berarbeitet. Die drei Buchstaben stehen f\"{u}r die Initialen der Magoi (gr.: Meister). Der Himmel basiert auf einem Screenshot von VRMoSS, dem Virtual Reality Model of the Solar System, entwickelt f\"{u}r das EU-Projekt "ASH" (http://www.ashproject.org, jetzt http://www.virtualcontrolroom.org). Es stellt den Blick auf den abendlichen Westhimmel im November des Jahres 7 v.u.Z. dar, an dem eine Konjunktion von Jupiter (K\"{o}nigsstern der chald\"{a}ischen Astrologie) und Saturn (Stern der Juden) vor dem Hintergrund der Fische (der Region Pal\"{a}stina zugeordnet) sichtbar war. Dieses Ereignis ist eine der besten nat\"{u}rlichen Erkl\"{a}rungen f\"{u}r den Biblischen "Stern der Weisen". Die Planeten sind stark vergr\"{o}{\ss}ert dargestellt. Der Lichtkegel des Zodiakallichts (an interplanetarem Staub gestreutes Sonnenlicht) wurde w\"{a}hrend der Nachbearbeitung eingef\"{u}gt. Das Gesamtbild wurde mit GIMP, dem freien GNU Image Manipulation Programm, erstellt. Idee, Materialien: Attila Neumann, Georg Zotti, Alexander Wilkie und andere. VRMoSS, Ausf\"{u}hrung: Georg Zotti (2002) The lower part of the image is a woodcut of Vienna taken from Hartmann Schedel's Chronicle Of The World (1493). The image "The Kings Follow the Star" was taken from the Atlas Catalan, Biblioth\`{e}que Nationale de France (14th Century) and slightly modified. According to central European tradition, one of the kings was a Moor. The three letters represent the initials of the Magi (gr.: Master). The sky image is a screenshot from VRMoSS (Virtual Reality Model of the Solar System), developed at our institute for the EU project "ASH" (http://www.ashproject.org, now http://www.virtualcontrolroom.org). It represents the evening sky of mid-November of the year 7 B.C.E., showing the close conjunction of Jupiter (star of the kings in Chaldean astrology) and Saturn (star of the Jews) - both greatly enlarged - in the constellation of Pisces (the fishes; related to Palestine), which is one of the best natural explanations of the biblical story of the star followed by the magi ("wise men" or "kings"). The light cone of the Zodiacal Light (sunlight reflected by dust in the Solar System) has been added during the postprocessing. The image has been composed with GIMP, the free GNU Image Manipulation Program. Idea, material: Attila Neumann, Georg Zotti, Alexander Wilkie, and others. VRMoSS, artwork: Georg Zotti (2002) ", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/xmas-2002/", } @article{tobler02_mbpls, title = "Mesh-Based Parametrized L-Systems and Generalized Subdivision for Generating Complex Geometry", author = "Robert F. Tobler and Stefan Maierhofer and Alexander Wilkie", year = "2002", journal = "International Journal of Shape Modeling", number = "2", volume = "8", pages = "173--191", URL = "https://www.cg.tuwien.ac.at/research/publications/2002/tobler02_mbpls/", } @techreport{Artusi-2001-NTD, title = "New Time-Dependent Tone mapping Algorithm", author = "Alessandro Artusi and Christian Faisstnauer and Alexander Wilkie", year = "2001", abstract = "In this report we present a new time-dependent tone mapping model which describes the ability of the human vision to adapt to even strong changes in the luminance of the surroundings. This ability depends on time; in fact the human visual system needs a determined amount of time until reaching the final stage of adaptation. Our model accepts the CIEXYZ values of an image as input and converts them into RGB values reproducible on a monitor. This work is based on the retinal model presented by Pattanaik et al. , but introducing substantial modifications. In fact, we define a new dynamic model which describes the time dependence of the human visual system, utilizing different filters; the cromatic adaptation is taken into account by introducing the model of von Kries. Furthermore, we introduce new techniques of gamut mapping and conversion between the values of retinal response and luminance of the display.", month = nov, number = "TR-186-2-01-21", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "colours, chromatic adaptation, appearance model, time-dependence, visual adaptation", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Artusi-2001-NTD/", } @techreport{wilkie-2001-crp, title = "Combined Rendering of Polarization and Fluorescence Effects", author = "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer", year = "2001", abstract = "We propose a practicable way to include both polarization and fluorescence effects in a rendering system at the same time. Previous research in this direction only demonstrated support for either one of these phenomena; using both effects simultaneously was so far not possible, mainly because the techniques for the treatment of polarized light were complicated and required rendering systems written specifically for this task. The key improvement over previous work is that we use a different, more easily handled formalism for the description of polarization state, which also enables us to include fluorescence effects in a natural fashion. Moreover, all of our proposals are straightforward extensions to a conventional spectral rendering system.", month = apr, number = "TR-186-2-01-11", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "predictive rendering, fluorescence, polarization", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/wilkie-2001-crp/", } @inproceedings{Artusi-2001-Col, title = "Color Printer Characterization Using Radial Basis Function Networks", author = "Alessandro Artusi and Alexander Wilkie", year = "2001", abstract = "Colorimetric characterization is one step in the colorimetric reproduction process that permits faithful image reproduction across different devices. Its goal is to define a mapping function between the device--dependent color spaces in question (such as RGB or CMYK) and device--independent colour spaces (such as CIELAB or CIEXYZ), and vice versa. The work presented in this paper is an application study of utilizing radial basis function networks for the problem of colorimetric characterization of printer devices. The work we present is novel in seven ways: to begin with, this is the first work that uses radial basis function networks to resolve the colorimetric characterization of printers. Second, we used a new learning model to train such networks; our approach is based on a proposal by Carozza. Third, we use only 125 measured samples for the training of the network. Fourth, the computational costs for this training are very low when compared to previous techniques and allow to use this model in consumer products. Fifth, it is a general model which one can also use to define other transformations between color spaces. Sixth, it is possible to have a fast recharacterization of the device because the computational cost of the training phase and the number of training samples are low. Finally, it improves on the performance of multiple polynomials regression and tetrahedral interpolation. ", month = jan, isbn = "0-8194-3978-9", publisher = "SPIE", note = "SPIE Conference, San Jose California, January 2001", location = "San Jose (USA)", booktitle = "Proceedings Colour Imaging Conference: Device-Independent Colour, Colour Hardcopy, and Graphics Arts VI, IST&SPIE, Electronic Imaging", pages = "70--80", keywords = "neural network, Colorimetric characterization", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Artusi-2001-Col/", } @misc{Wilkie-2001-Com, title = "Combined Rendering of Polarization and Fluorescence Effects", author = "Werner Purgathofer and Alexander Wilkie and Robert F. Tobler", year = "2001", note = "In Rendering Techniques'01 (proceedings of Eurographics Workshop on Rendering 2001), June 2001, Springer- Verlag, Wien, 2001", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Wilkie-2001-Com/", } @article{Wilkie-2001-Ori, title = "Orientation Lightmaps for Photon Radiosity in Complex Environments", author = "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer", year = "2001", abstract = "We present a method that makes the use of photon tracing methods feasible for complex scenes when a totally accurate solution is not essential. This is accomplished by using orientation lightmaps, which average the illumination of complex objects depending on the surface normal. Through this averaging, they considerably reduce the variance of the stochastic solution. In order to use these specialised lightmaps, which consume comparatively small amounts of memory, no changes have to be made to the basic photon-tracing algorithm. Also, they can be freely mixed with normal lightmaps. This gives the user good control over the amount of inaccuracy he introduces by their application. The area computations necessary for their insertion are performed using a stochastic sampling method that performs well for highly complex objects.", journal = "The Visual Computer", note = "In The Visual Computer, Vol. 17, No. 5, pp. 318-327, Springer, Heidelberg, 2001", URL = "https://www.cg.tuwien.ac.at/research/publications/2001/Wilkie-2001-Ori/", } @phdthesis{Wilkie-thesis, title = "Photon Tracing for Complex Environments", author = "Alexander Wilkie", 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/Wilkie-thesis/", } @misc{Wilkie-2000-Ray, title = "Raytracing of Dispersion Effects", author = "Werner Purgathofer and Alexander Wilkie and Robert F. Tobler", year = "2000", note = "In Proceedings of WSCG2000, Plzen, Czech Republic, February 2000", URL = "https://www.cg.tuwien.ac.at/research/publications/2000/Wilkie-2000-Ray/", } @techreport{wilkie-1999-ORI, title = "Orientation Lightmaps for Photon Radiosity in Complex Environments", author = "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer", year = "1999", abstract = "We present a method that makes the use of photon radiosity methods feasi ble for complex scenes when a totally accurate solution is not essential. This is accompl ished by using {\em orientation lightmaps}, which average the illumination of complex obj ects depending on the surface normal. Through this averaging, they considerably reduce th e variance of the stochastic solution. For the use of these specialised lightmaps, which consume comparatively small amounts of memory, no changes have to be made to the actual p hoton tracing algorithm. Also, they can be freely mixed with normal lightmaps and inserte d at any point in the scene description graph. This gives the user good control over the amount of inaccuracy he introduces by their application. The area computations necessary for their insertion are performed using a stochastic sampling method that performs well f or highly complex objects.", month = apr, number = "TR-186-2-99-11", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "lightmaps, complex scenes, photon radiosity, global illumination", URL = "https://www.cg.tuwien.ac.at/research/publications/1999/wilkie-1999-ORI/", } @misc{Wilkie-1999-ASp, title = "A Spectral Extension to the Tagged Image File Format.", author = "Werner Purgathofer and Alexander Wilkie and Robert F. Tobler", year = "1999", note = "Short Communications of The Seventh International Conference in Central Europe on Computer Graphics, Visualisation and Digital Interactive Media '99, University of West Bohemia, Pilsen, Czech Republic, February 1999.", URL = "https://www.cg.tuwien.ac.at/research/publications/1999/Wilkie-1999-ASp/", } @techreport{Wilkie-1998-Ase, title = "A Spectral Extension to the Tag Image File Format", author = "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer", year = "1998", abstract = "We propose a simple, consistent and yet powerful extension to the Tagged Image File Format (commonly referred to as TIFF) that enables the user to store spectral image data.", month = oct, number = "TR-186-2-98-28", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "image file format, spectral rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/1998/Wilkie-1998-Ase/", } @misc{Wilkie-1998-Pho, title = "Photon Radiosity Lightmaps for CSG Solids", author = "Werner Purgathofer and Alexander Wilkie and Robert F. Tobler", year = "1998", note = "In Proceedings of the CSG98 conference "CSG98 - Set theoretic Solid Modelling Techniques and Applications", Ammerdown, UK, April 1998.", URL = "https://www.cg.tuwien.ac.at/research/publications/1998/Wilkie-1998-Pho/", } @xmascard{xmas-1998, title = "X-Mas 1998", author = "Alexander Wilkie", year = "1998", abstract = "Die Schneeflocken wurden mit ART (Advanced Rendering Toolkit), einem am Institut fur Computergraphik entwickelten Programmsystem zur Berechnung von realistischen Bildern, erzeugt. Als Vorlage dienten Photos von echten Schneeflocken. Die sichtbaren Farbeffekte entstehen durch physikalisch korrekte Simulation der Lichtbrechung. Dieses Bild ist auch in seiner vollen Aufl\"{o}sung von 1536x1024 im von Greg Larson et al. eingef\"{u}hrten TIFF LogLuv-Format zum Download bereit (es unterst\"{u}tzen leider erst sehr wenige Programme diese Erweiterung des TIFF-Formates). This image was rendered with the spectral ray tracer of ART, the Advanced Rendering Toolkit, a software package for rendering realistic images developed at the Institute of Computer Graphics. The snowflakes have been modelled based on photos of real snowflakes. The colour effects are due to the use of a physically correct simulation of light dispersion. You can also download this image in the high dynamic range TIFF LogLuv image format developed by Greg Larson et al. in full 1536x1024 resolution here (note that most programs are not yet able to view this extension to the TIFF format).", URL = "https://www.cg.tuwien.ac.at/research/publications/1998/xmas-1998/", } @techreport{Wilkie-1997-PRL, title = "Photon Radiosity Lightmaps for CSG Solids", author = "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer", year = "1997", abstract = "We propose a technique that enables one to exploit the inherent ability of stochastic radiosity algorithms to work correctly in the presence of arbitrary CSG intersections. With such radiosity algorithms the common approach to storing the illumination over a surface is to attach so--called {\em lightmaps} to them. By suitably splitting those lightmap elements at set--up time that are partitioned in some way by CSG intersections, we create an environment where a photon simulation can be performed without any modifications to the algorithm and little run--time penalty.", month = sep, number = "TR-186-2-97-19", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "CSG, functional radiosity, stochastic radiosity, lightmaps", URL = "https://www.cg.tuwien.ac.at/research/publications/1997/Wilkie-1997-PRL/", } @inproceedings{tobler97_hsdasr, title = "A Hierarchical Subdivision Algorithm for Stochastic Radiosity Methods", author = "Robert F. Tobler and Alexander Wilkie and Martin Feda and Werner Purgathofer", year = "1997", abstract = "The algorithm proposed in this paper uses a stochastic approach to incrementally calculate the illumination function over a surface. By tracking the illumination function at different levels of meshing resolution, it is possible to get a measure for the quality of the current representation, and to adoptively subdivide in places with inadequate accuracy. With this technique a hierarchical mesh that is based on the stochastic evaluation of global illumination is generated.", month = jun, publisher = "Springer Wien", organization = "Eurographics", address = "St. Etienne, France", editor = "Julie Dorsey and Philipp Slusallek", booktitle = "Eurographics Rendering Workshop 1997", pages = "193--204", keywords = "radiosity, monte carlo methods", URL = "https://www.cg.tuwien.ac.at/research/publications/1997/tobler97_hsdasr/", } @xmascard{xmas-1997, title = "X-Mas 1997", author = "Alexander Wilkie", year = "1997", abstract = "This image was rendered with the ray tracer of ART, the Advanced Rendering Toolkit, a software package for rendering realistic images developed at the Institute of Computer Graphics. ART includes multiple rendering technologies and is intended as a development platform for research in global illumination.", URL = "https://www.cg.tuwien.ac.at/research/publications/1997/xmas-1997/", } @techreport{Tobler-1996-HSA, title = "A Hierarchical Subdivision Algorithm for Stochastic Radiosity Methods", author = "Robert F. Tobler and Martin Feda and Werner Purgathofer and Alexander Wilkie", year = "1996", abstract = "Stochastic radiosity methods have become a standard tool for generating global illumination solutions for very large scenes. Unfortunately, these methods need scene descriptions that are premeshed to a very fine resolution, in order to compute an adequate solution of the global illumination. The algorithm proposed in this paper uses a stochastic Galerkin approach to incrementally calculate the illumination function. By tracking the illumination function at different levels of resolution it is possible to get a measure for the quality of the representation, and thus adaptively subdivide in places with inadequate accuracy. With this technique a hierarchical mesh is generated, that is based on the stochastic evaluation of global illumination.", month = apr, number = "TR-186-2-96-14", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", note = "human contact: technical-report@cg.tuwien.ac.at", keywords = "radiosity, stochastic, Monte Carlo, hierarchical, Galerkin, density estimation", URL = "https://www.cg.tuwien.ac.at/research/publications/1996/Tobler-1996-HSA/", }