@article{hecher-2014-MH, title = "A Comparative Perceptual Study of Soft Shadow Algorithms", author = "Michael Hecher and Matthias Bernhard and Oliver Mattausch and Daniel Scherzer and Michael Wimmer", year = "2014", abstract = "We performed a perceptual user study of algorithms that approximate soft shadows in real time. Although a huge body of soft-shadow algorithms have been proposed, to our knowledge this is the first methodical study for comparing different real-time shadow algorithms with respect to their plausibility and visual appearance. We evaluated soft-shadow properties like penumbra overlap with respect to their relevance to shadow perception in a systematic way, and we believe that our results can be useful to guide future shadow approaches in their methods of evaluation. In this study, we also capture the predominant case of an inexperienced user observing shadows without comparing to a reference solution, such as when watching a movie or playing a game. One important result of this experiment is to scientifically verify that real-time soft-shadow algorithms, despite having become physically based and very realistic, can nevertheless be intuitively distinguished from a correct solution by untrained users.", month = jun, issn = "1544-3558", journal = "ACM Transactions on Applied Perception", number = "5", volume = "11", pages = "5:1--5:21", keywords = "Perception Studies, Soft Shadows", URL = "https://www.cg.tuwien.ac.at/research/publications/2014/hecher-2014-MH/", } @inproceedings{SCHWAERZLER-2013-FPCSS, title = "Fast Percentage Closer Soft Shadows using Temporal Coherence", author = "Michael Schw\"{a}rzler and Christian Luksch and Daniel Scherzer and Michael Wimmer", year = "2013", abstract = "We propose a novel way to efficiently calculate soft shadows in real-time applications by overcoming the high computational effort involved with the complex corresponding visibility estimation each frame: We exploit the temporal coherence prevalent in typical scene movement, making the estimation of a new shadow value only necessary whenever regions are newly disoccluded due to camera adjustment, or the shadow situation changes due to object movement. By extending the typical shadow mapping algorithm by an additional light-weight buffer for the tracking of dynamic scene objects, we can robustly and efficiently detect all screen space fragments that need to be updated, including not only the moving objects themselves, but also the soft shadows they cast. By applying this strategy to the popular Percentage Closer Soft Shadow algorithm (PCSS), we double rendering performance in scenes with both static and dynamic objects - as prevalent in various 3D game levels - while maintaining the visual quality of the original approach.", month = mar, isbn = "978-1-4503-1956-0", publisher = "ACM", location = "Orlando, Florida", address = "New York, NY, USA", booktitle = "Proceedings of ACM Symposium on Interactive 3D Graphics and Games 2013", pages = "79--86", keywords = "real-time, temporal coherence, soft shadows", URL = "https://www.cg.tuwien.ac.at/research/publications/2013/SCHWAERZLER-2013-FPCSS/", } @article{SCHERZER-2012-TCM, title = "Temporal Coherence Methods in Real-Time Rendering", author = "Daniel Scherzer and Lei Yang and Oliver Mattausch and Diego Nehab and Pedro V. Sander and Michael Wimmer and Elmar Eisemann", year = "2012", abstract = "Nowadays, there is a strong trend towards rendering to higher-resolution displays and at high frame rates. This development aims at delivering more detail and better accuracy, but it also comes at a significant cost. Although graphics cards continue to evolve with an ever-increasing amount of computational power, the speed gain is easily counteracted by increasingly complex and sophisticated shading computations. For real-time applications, the direct consequence is that image resolution and temporal resolution are often the first candidates to bow to the performance constraints (e.g., although full HD is possible, PS3 and XBox often render at lower resolutions). In order to achieve high-quality rendering at a lower cost, one can exploit temporal coherence (TC). The underlying observation is that a higher resolution and frame rate do not necessarily imply a much higher workload, but a larger amount of redundancy and a higher potential for amortizing rendering over several frames. In this survey, we investigate methods that make use of this principle and provide practical and theoretical advice on how to exploit temporal coherence for performance optimization. These methods not only allow incorporating more computationally intensive shading effects into many existing applications, but also offer exciting opportunities for extending high-end graphics applications to lower-spec consumer-level hardware. To this end, we first introduce the notion and main concepts of TC, including an overview of historical methods. We then describe a general approach, image-space reprojection, with several implementation algorithms that facilitate reusing shading information across adjacent frames. We also discuss data-reuse quality and performance related to reprojection techniques. Finally, in the second half of this survey, we demonstrate various applications that exploit TC in real-time rendering. ", month = dec, issn = "1467-8659", journal = "Computer Graphics Forum", number = "8", volume = "31", pages = "2378--2408", keywords = "remote rendering; sampling, perception-based rendering, occlusion culling, non-photo-realistic rendering, level-of-detail, large data visualization, image-based rendering, global illumination, frame interpolation, anti-aliasing, shadows, streaming, temporal coherance, upsampling", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/SCHERZER-2012-TCM/", } @inproceedings{SCHWAERZLER-2012-FAS, title = "Fast Accurate Soft Shadows with Adaptive Light Source Sampling", author = "Michael Schw\"{a}rzler and Oliver Mattausch and Daniel Scherzer and Michael Wimmer", year = "2012", abstract = "Physically accurate soft shadows in 3D applications can be simulated by taking multiple samples from all over the area light source and accumulating them. Due to the unpredictability of the size of the penumbra regions, the required sampling density has to be high in order to guarantee smooth shadow transitions in all cases. Hence, several hundreds of shadow maps have to be evaluated in any scene configuration, making the process computationally expensive. Thus, we suggest an adaptive light source subdivision approach to select the sampling points adaptively. The main idea is to start with a few samples on the area light, evaluating there differences using hardware occlusion queries, and adding more sampling points if necessary. Our method is capable of selecting and rendering only the samples which contribute to an improved shadow quality, and hence generate shadows of comparable quality and accuracy. Even though additional calculation time is needed for the comparison step, this method saves valuable rendering time and achieves interactive to real-time frame rates in many cases where a brute force sampling method does not. ", month = nov, isbn = "978-3-905673-95-1", publisher = "Eurographics Association", location = "Magdeburg, Germany", booktitle = "Proceedings of the 17th International Workshop on Vision, Modeling, and Visualization (VMV 2012)", pages = "39--46", keywords = "soft shadows, real-time rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/SCHWAERZLER-2012-FAS/", } @article{MATTAUSCH-2012-TIS, title = "Tessellation-Independent Smooth Shadow Boundaries", author = "Oliver Mattausch and Daniel Scherzer and Michael Wimmer and Takeo Igarashi", year = "2012", abstract = "We propose an efficient and light-weight solution for rendering smooth shadow boundaries that do not reveal the tessellation of the shadow-casting geometry. Our algorithm reconstructs the smooth contours of the underlying mesh and then extrudes shadow volumes from the smooth silhouettes to render the shadows. For this purpose we propose an improved silhouette reconstruction using the vertex normals of the underlying smooth mesh. Then our method subdivides the silhouette loops until the contours are sufficiently smooth and project to smooth shadow boundaries. This approach decouples the shadow smoothness from the tessellation of the geometry and can be used to maintain equally high shadow quality for multiple LOD levels. It causes only a minimal change to the fill rate, which is the well-known bottleneck of shadow volumes, and hence has only small overhead. ", month = jun, journal = "Computer Graphics Forum", volume = "4", number = "31", issn = "1467-8659", pages = "1465--1470", keywords = "real-time rendering, shadows", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/MATTAUSCH-2012-TIS/", } @incollection{MATTAUSCH-2012-EOV, title = "Efficient Online Visibility for Shadow Maps", author = "Oliver Mattausch and Jir\'{i} Bittner and Ari Silvennoinen and Daniel Scherzer and Michael Wimmer", year = "2012", abstract = "Standard online occlusion culling is able to vastly improve the rasterization performance of walkthrough applications by identifying large parts of the scene as invisible from the camera and rendering only the visible geometry. However, it is of little use for the acceleration of shadow map generation (i.e., rasterizing the scene from the light view [Williams 78]), so that typically a high percentage of the geometry will be visible when rendering shadow maps. For example, in outdoor scenes typical viewpoints are near the ground and therefore have significant occlusion, while light viewpoints are higher up and see most of the geometry. Our algorithm remedies this situation by quickly detecting and culling the geometry that does not contribute to the shadow in the final image.", month = feb, booktitle = "GPU Pro 3: Advanced Rendering Techniques", editor = "Wolfgang Engel", isbn = "978-1439887820", publisher = "CRC Press", keywords = "shadow maps, visibility culling", URL = "https://www.cg.tuwien.ac.at/research/publications/2012/MATTAUSCH-2012-EOV/", } @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{scherzer2011d, title = "A Survey of Real-Time Hard Shadow Mapping Methods", author = "Daniel Scherzer and Michael Wimmer and Werner Purgathofer", year = "2011", abstract = "Due to its versatility, speed and robustness, shadow mapping has always been a popular algorithm for fast hard shadow generation since its introduction in 1978, first for off-line film productions and later increasingly so in real-time graphics. So it is not surprising that recent years have seen an explosion in the number of shadow map related publications. The last survey that encompassed shadow mapping approaches, but was mainly focused on soft shadow generation, dates back to 2003~cite{HLHS03}, while the last survey for general shadow generation dates back to 1990~cite{Woo:1990:SSA}. No survey that describes all the advances made in hard shadow map generation in recent years exists. On the other hand, shadow mapping is widely used in the game industry, in production, and in many other applications, and it is the basis of many soft shadow algorithms. Due to the abundance of articles on the topic, it has become very hard for practitioners and researchers to select a suitable shadow algorithm, and therefore many applications miss out on the latest high-quality shadow generation approaches. The goal of this survey is to rectify this situation by providing a detailed overview of this field. We provide a detailed analysis of shadow mapping errors and derive a comprehensive classification of the existing methods. We discuss the most influential algorithms, consider their benefits and shortcomings and thereby provide the readers with the means to choose the shadow algorithm best suited to their needs. ", month = feb, issn = "0167-7055", journal = "Computer Graphics Forum", number = "1", volume = "30", pages = "169--186", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/scherzer2011d/", } @incollection{2011scherzerE, title = "Fast Soft Shadows with Temporal Coherence", author = "Daniel Scherzer and Michael Schw\"{a}rzler and Oliver Mattausch", year = "2011", month = feb, booktitle = "GPU Pro 2", editor = "Wolfgang Engel", isbn = "978-1568817187", publisher = "A.K. Peters", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/2011scherzerE/", } @incollection{matt2011, title = "Temporal Screen-Space Ambient Occlusion", author = "Oliver Mattausch and Daniel Scherzer and Michael Wimmer", year = "2011", month = feb, booktitle = "GPU Pro 2", editor = "Wolfgang Engel", isbn = "978-1568817187", publisher = "A.K. Peters", keywords = "ambient occlusion", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/matt2011/", } @inproceedings{scherzer2011c, title = "A Survey on Temporal Coherence Methods in Real-Time Rendering", author = "Daniel Scherzer and Lei Yang and Oliver Mattausch and Diego Nehab and Pedro V. Sander and Michael Wimmer and Elmar Eisemann", year = "2011", abstract = "Nowadays, there is a strong trend towards rendering to higher-resolution displays and at high frame rates. This development aims at delivering more detail and better accuracy, but it also comes at a significant cost. Although graphics cards continue to evolve with an ever-increasing amount of computational power, the processing gain is counteracted to a high degree by increasingly complex and sophisticated pixel computations. For real-time applications, the direct consequence is that image resolution and temporal resolution are often the first candidates to bow to the performance constraints (e.g., although full HD is possible, PS3 and XBox often render at lower resolutions). In order to achieve high-quality rendering at a lower cost, one can exploit emph{temporal coherence} (TC). The underlying observation is that a higher resolution and frame rate do not necessarily imply a much higher workload, but a larger amount of redundancy and a higher potential for amortizing rendering over several frames. In this STAR, we will investigate methods that make use of this principle and provide practical and theoretical advice on how to exploit temporal coherence for performance optimization. These methods not only allow us to incorporate more computationally intensive shading effects into many existing applications, but also offer exciting opportunities for extending high-end graphics applications to lower-spec consumer-level hardware. To this end, we first introduce the notion and main concepts of TC, including an overview of historical methods. We then describe a key data structure, the so-called emph{reprojection cache}, with several supporting algorithms that facilitate reusing shading information from previous frames. Its usefulness is illustrated in the second part of the STAR, where we present various applications. We illustrate how expensive pixel shaders, multi-pass shading effects, stereo rendering, shader antialiasing, shadow casting, and global-illumination effects can profit from pixel reuse. Furthermore, we will see that optimizations for visibility culling and object-space global illumination can also be achieved by exploiting TC. This STAR enables the reader to gain an overview of many techniques in this cutting-edge field and provides many insights into algorithmic choices and implementation issues. It delivers working knowledge of how various existing techniques are optimized via data reuse. Another goal of this STAR is to inspire the reader and to raise awareness for temporal coherence as an elegant tool that could be a crucial component to satisfy the recent need for higher resolution and more detailed content. ", booktitle = "EUROGRAPHICS 2011 State of the Art Reports", location = "Llandudno UK", publisher = "Eurographics Association", pages = "101--126", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/scherzer2011c/", } @article{mattausch-2010-tao, title = "High-Quality Screen-Space Ambient Occlusion using Temporal Coherence", author = "Oliver Mattausch and Daniel Scherzer and Michael Wimmer", year = "2010", abstract = "Ambient occlusion is a cheap but effective approximation of global illumination. Recently, screen-space ambient occlusion (SSAO) methods, which sample the frame buffer as a discretization of the scene geometry, have become very popular for real-time rendering. We present temporal SSAO (TSSAO), a new algorithm which exploits temporal coherence to produce high-quality ambient occlusion in real time. Compared to conventional SSAO, our method reduces both noise as well as blurring artifacts due to strong spatial filtering, faithfully representing fine-grained geometric structures. Our algorithm caches and reuses previously computed SSAO samples, and adaptively applies more samples and spatial filtering only in regions that do not yet have enough information available from previous frames. The method works well for both static and dynamic scenes.", month = dec, issn = "0167-7055", journal = "Computer Graphics Forum", number = "8", volume = "29", pages = "2492--2503", keywords = "temporal coherence, ambient occlusion, real-time rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/mattausch-2010-tao/", } @inproceedings{scherzer2010e, title = "An Overview of Temporal Coherence Methods in Real-Time Rendering ", author = "Daniel Scherzer", year = "2010", abstract = "Most of the power of modern graphics cards is put into the acceleration of shading tasks because here lies the major bottleneck for most sophisticated real-time algorithms. By using temporal coherence, i.e. reusing shading information from a previous frame, this problem can be alleviated. This paper gives an overview of the concepts of temporal coherence in real-time rendering and should give the reader the working practical and theoretical knowledge to exploit temporal coherence in his own algorithms. ", month = oct, organization = "IEEE", location = "Sinaia, Romania", issn = "2068-0465", booktitle = " 14th International Conference on System Theory and Control 2010", pages = "497--502", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/scherzer2010e/", } @article{bagar2010, title = "A Layered Particle-Based Fluid Model for Real-Time Rendering of Water", author = "Florian Bagar and Daniel Scherzer and Michael Wimmer", year = "2010", abstract = "We present a physically based real-time water simulation and rendering method that brings volumetric foam to the real-time domain, significantly increasing the realism of dynamic fluids. We do this by combining a particle-based fluid model that is capable of accounting for the formation of foam with a layered rendering approach that is able to account for the volumetric properties of water and foam. Foam formation is simulated through Weber number thresholding. For rendering, we approximate the resulting water and foam volumes by storing their respective boundary surfaces in depth maps. This allows us to calculate the attenuation of light rays that pass through these volumes very efficiently. We also introduce an adaptive curvature flow filter that produces consistent fluid surfaces from particles independent of the viewing distance.", month = jun, journal = "Computer Graphics Forum (Proceedings EGSR 2010)", volume = "29", number = "4", issn = "0167-7055", pages = "1383--1389", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/bagar2010/", } @inproceedings{scherzer2010d, title = "Exploiting Temporal Coherence in Real-Time Rendering", author = "Daniel Scherzer and Lei Yang and Oliver Mattausch", year = "2010", abstract = "Temporal coherence (TC), the correlation of contents between adjacent rendered frames, exists across a wide range of scenes and motion types in practical real-time rendering. By taking advantage of TC, we can save redundant computation and improve the performance of many rendering tasks significantly with only a marginal decrease in quality. This not only allows us to incorporate more computationally intensive shading effects to existing applications, but also offers exciting opportunities of extending high-end graphics applications to reach lower-spec consumer-level hardware. This course aims to introduce participants to the concepts of TC, and provide them the working practical and theoretical knowledge to exploit TC in a variety of shading tasks. It begins with an introduction of the general notion of TC in rendering, as well as an overview of the recent developments in this field. Then it focuses on a key data structure - the reverse reprojection cache, which is the foundation of many applications. The course proceeds with a number of extensions of the basic algorithm for assisting in multi-pass shading effects, shader antialiasing, casting shadows and global-illumination effects. Finally, several more general coherence topics beyond pixel reuse are introduced, including visibility culling optimization and object-space global-illumination approximations. For all the major techniques and applications covered, implementation and practical issues involved in development are addressed in detail. In general, we emphasize "know how" and the guidelines related to algorithm choices. After the course, participants are encouraged to find and utilize TC in their own applications and rapidly adapt existing algorithms to meet their requirements.", booktitle = "SIGGRAPH Asia 2010 Courses", location = "Seoul, S\"{u}dkorea", keywords = "shadows, temporal coherence, real-time, rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/scherzer2010d/", } @book{scherzer2010b, title = "Temporal Coherence in Real-Time Rendering", author = "Daniel Scherzer", year = "2010", abstract = "Real-time rendering imposes the challenging task of creating a new rendering of an input scene at least 60 times per second. Although computer graphics hardware has made staggering advances in terms of speed and freedom of programmability in recent years, there still exists a number of algorithms that are just too expensive to be calculated in this time budget, like for instance exact shadows or an exact global illumination solution. One way to circumvent this hard time limit is to capitalize on temporal coherence to formulate algorithms incremental in time. To this end, three algorithms which successfully incorporate temporal coherence are analysed in detail. To highlight the benefits which are provided by these new practical algorithms, this book also includes the respective previous work. This includes not only the field of temporal coherence, but also the fields of real-time hard and soft shadows and discrete LOD blending. This book targets computer scientists and students with prior knowledge in real-time rendering.", isbn = "978-3-639-09196-0", pages = "122", publisher = "Verlag Dr. M\"{u}ller", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/scherzer2010b/", } @inproceedings{scherzer_2010a, title = "A Survey of Real-Time Hard Shadow Mapping Methods", author = "Daniel Scherzer and Michael Wimmer and Werner Purgathofer", year = "2010", abstract = "Due to its versatility, speed and robustness, shadow mapping has always been a popular algorithm for fast hard shadow generation since its introduction in 1978, first for off-line film productions and later increasingly so in real-time graphics. So it is not surprising that recent years have seen an explosion in the number of shadow map related publications. The last survey that encompassed shadow mapping approaches, but was mainly focused on soft shadow generation, dates back to 2003~cite{HLHS03} and the last survey for general shadow generation dates back to 1990~cite{Woo:1990:SSA}. No survey that describes all the advances made in hard shadow map generation in recent years exists. On the other hand, shadow mapping is widely used in the game industry, in production, and in many other applications, and it is the basis of many soft shadow algorithms. Due to the abundance of articles on the topic, it has become very hard for practioners and researchers to select a suitable shadow algorithm, and therefore many applications miss out on the latest high-quality shadow generation approaches. %Real-time research was always tempted to bring global lighting techniques into the real-time domain. One of the most popular adaptations in this respect are hard shadows. It is therefore not surprising that real-time hard shadow generation has been one of the most active areas in research in recent years. But what is surprising is that the last state-of-the-art report that encompassed this field dates back to 1990~cite{Woo:1990:SSA}, were only the beginnings of this field were explored. The goal of this survey is to rectify this situation by providing a detailed overview of this field. We provide a detailed analysis of shadow mapping errors and derive from this a comprehensive classification of the existing methods. We discuss the most influential algorithms, consider their benefits and shortcomings and thereby provide the reader with the means to choose the shadow algorithm best suited to her needs.", booktitle = "EUROGRAPHICS 2010 State of the Art Reports", location = "Norrk\"{o}ping, Sweden", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/scherzer_2010a/", } @WorkshopTalk{scherzer2009c, title = "Casting Shadows in Real Time", author = "Michael Schwarz and Elmar Eisemann and Ulf Assarsson and Daniel Scherzer", year = "2009", abstract = "Shadows are crucial for enhancing realism, and they provide important visual cues. In recent years, many important contributions have been made in representation of both hard shadows and soft shadows. With the tremendous increase of computational power and capabilities of graphics hardware, high-quality real-time shadows are now a reachable goal. But with the growing volume of available choices, it is particularly difficult to pick the right solution and assess product shortcomings. Because currently there is no ideal approach available, algorithms should be selected in accordance with the context in which shadows are produced. The possibilities range across a wide spectrum, from very approximate but really efficient to slower but accurate, adapted only to smaller or only to larger sources, addressing directional lights or positional lights, or involving GPU or CPU-heavy computations. This course is a guide to better understanding of the limitations and failure cases, advantages and disadvantages, and suitability of the algorithms for different application scenarios. It focuses on real-time, interactive solutions but also discusses offline approaches.", month = dec, event = "SIGGRAPH Asia Course", location = "Yokohama, Japan", keywords = "shadows, real-time", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/scherzer2009c/", } @inproceedings{SSMW09, title = "Real-Time Soft Shadows Using Temporal Coherence", author = "Daniel Scherzer and Michael Schw\"{a}rzler and Oliver Mattausch and Michael Wimmer", year = "2009", abstract = "A vast amount of soft shadow map algorithms have been presented in recent years. Most use a single sample hard shadow map together with some clever filtering technique to calculate perceptually or even physically plausible soft shadows. On the other hand there is the class of much slower algorithms that calculate physically correct soft shadows by taking and combining many samples of the light. In this paper we present a new soft shadow method that combines the benefits of these approaches. It samples the light source over multiple frames instead of a single frame, creating only a single shadow map each frame. Where temporal coherence is low we use spatial filtering to estimate additional samples to create correct and very fast soft shadows. ", month = dec, isbn = "978-3642103308", series = "Lecture Notes in Computer Science", publisher = "Springer", location = "Las Vegas, Nevada, USA", editor = "Bebis, G.; Boyle, R.; Parvin, B.; Koracin, D.; Kuno, Y.; Wang, J.; Pajarola, R.; Lindstrom, P.; Hinkenjann, A.; Encarnacao, M.; Silva, C.; Coming, D.", booktitle = "Advances in Visual Computing: 5th International Symposium on Visual Computing (ISVC 2009)", pages = "13--24", keywords = "real-time rendering, soft shadows", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/SSMW09/", } @phdthesis{scherzer-thesis, title = "Applications of temporal coherence in real-time rendering", author = "Daniel Scherzer", year = "2009", abstract = "Real-time rendering imposes the challenging task of creating a new rendering of an input scene at least 60 times a second. Although computer graphics hardware has made staggering advances in terms of speed and freedom of programmability, there still exist a number of algorithms that are too expensive to be calculated in this time budget, like exact shadows or an exact global illumination solution. One way to circumvent this hard time limit is to capitalize on temporal coherence to formulate algorithms incremental in time. The main thesis of this work is that temporal coherence is a characteristic of real-time graphics that can be used to redesign well-known rendering methods to become faster, while exhibiting better visual fidelity. To this end we present our adaptations of algorithms from the fields of exact hard shadows, physically correct soft shadows and fast discrete LOD blending, in which we have successfully incorporated temporal coherence. Additionally, we provide a detailed context of previous work not only in the field of temporal coherence, but also in the respective fields of the presented algorithms.", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "shadows, lod, real-time, image-space", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/scherzer-thesis/", } @article{SCHERZER-2008-FSR, title = "Frame Sequential Interpolation for Discrete Level-of-Detail Rendering", author = "Daniel Scherzer and Michael Wimmer", year = "2008", abstract = "In this paper we present a method for automatic interpolation between adjacent discrete levels of detail to achieve smooth LOD changes in image space. We achieve this by breaking the problem into two passes: We render the two LOD levels individually and combine them in a separate pass afterwards. The interpolation is formulated in a way that only one level has to be updated per frame and the other can be reused from the previous frame, thereby causing roughly the same render cost as with simple non interpolated discrete LOD rendering, only incurring the slight overhead of the final combination pass. Additionally we describe customized interpolation schemes using visibility textures. The method was designed with the ease of integration into existing engines in mind. It requires neither sorting nor blending of objects, nor does it introduce any constrains in the LOD used. The LODs can be coplanar, alpha masked, animated, impostors, and intersecting, while still interpolating smoothly. ", month = jun, journal = "Computer Graphics Forum (Proceedings EGSR 2008)", volume = "27", number = "4", issn = "0167-7055", pages = "1175--1181", keywords = "LOD blending, real-time rendering, levels of detail", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/SCHERZER-2008-FSR/", } @inproceedings{Scherzer-2007-PCS, title = "Pixel-Correct Shadow Maps with Temporal Reprojection and Shadow Test Confidence", author = "Daniel Scherzer and Stefan Jeschke and Michael Wimmer", year = "2007", abstract = "Shadow mapping suffers from spatial aliasing (visible as blocky shadows) as well as temporal aliasing (visible as flickering). Several methods have already been proposed for reducing such artifacts, but so far none is able to provide satisfying results in real time. This paper extends shadow mapping by reusing information of previously rasterized images, stored efficiently in a so-called history buffer. This buffer is updated in every frame and then used for the shadow calculation. In combination with a special confidence-based method for the history buffer update (based on the current shadow map), temporal and spatial aliasing can be completely removed. The algorithm converges in about 10 to 60 frames and during convergence, shadow borders are sharpened over time. Consequently, in case of real-time frame rates, the temporal shadow adaption is practically imperceptible. The method is simple to implement and is as fast as uniform shadow mapping, incurring only the minor speed hit of the history buffer update. It works together with advanced filtering methods like percentage closer filtering and more advanced shadow mapping techniques like perspective or light space perspective shadow maps.", month = jun, isbn = "978-3-905673-52-4", publisher = "Eurographics Association", organization = "Eurographics", location = "Grenoble, France", editor = "Jan Kautz and Sumanta Pattanaik", booktitle = "Rendering Techniques 2007 (Proceedings Eurographics Symposium on Rendering)", pages = "45--50", keywords = "shadow mapping", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/Scherzer-2007-PCS/", } @incollection{Wimmer-2006, title = "Robust Shadow Mapping with Light Space Perspective Shadow Maps", author = "Michael Wimmer and Daniel Scherzer", year = "2006", abstract = "In this paper, we present a new shadow mapping technique that improves upon the quality of perspective and uniform shadow maps. Our technique uses a perspective transform specified in light space which allows treating all lights as directional lights and does not change the direction of the light sources. This gives all the benefits of the perspective mapping but avoids the problems inherent in perspective shadow mapping like singularities in post-perspective space, missed shadow casters etc. Furthermore, we show that both uniform and perspective shadow maps distribute the perspective aliasing error that occurs in shadow mapping unequally over the available depth range. We therefore propose a transform that equalizes this error and gives equally pleasing results for near and far viewing distances. Our method is simple to implement, requires no scene analysis and is therefore as fast as uniform shadow mapping.", month = mar, booktitle = "ShaderX 4 -- Advanced Rendering Techniques", editor = "Wolfgang Engel", isbn = "1-58450-425-0", publisher = "Charles River Media", series = "ShaderX", volume = "4", keywords = "real-time rendering, shadows", URL = "https://www.cg.tuwien.ac.at/research/publications/2006/Wimmer-2006/", } @mastersthesis{S05, title = "Shadow Mapping of Large Environments", author = "Daniel Scherzer", year = "2005", abstract = "This thesis is about shadow generation in real-time and its problems. Its focus is on shadow mapping, a real-time technique to render high quality shadows. A lot of literature is available concerning shadow mapping and the problems associated with it. But most of this literature concerns itself only with certain problematic parts of shadow mapping, but not with all the problems of shadow mapping together. In this thesis we will give a minute report of all these problems and why and how they occur. We will discuss the major methods to cure them and identify and adopt the methods so that they can be used together for demanding real-time applications to avoid all of the shadow mapping problems. All things considered this thesis should provide an insight into the current state of research in the field of real-time shadow generation with shadow maps, and should expand this overview by giving the reader all the methods at hand to cure the problems of shadow mapping and use it in a complex real-time scenario without visible artefacts.", month = aug, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "real-time rendering, shadow mapping", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/S05/", } @inproceedings{Scherzer_2005, title = "Robust Shadow Maps for Large Environments", author = "Daniel Scherzer", year = "2005", abstract = "One of the most demanding challenges for real-time shadow algorithms is their application to large-scale, polygon-rich and dynamic environments. In this paper, we discuss the major problems encountered in applying shadow maps to such an environment and provide practical and robust solutions to the appearing problems. We tackle projection aliasing with the aid of an eye space blur. We compare the major biasing methods to remove incorrect self-shadowing of polygons. Finally we are providing some advancements to the recently published light space perspective shadow mapping method to resolve projection aliasing problems. ", publisher = "Eigenverlag", booktitle = "Proceedings of the Central European Seminar on Computer Graphics 2005", keywords = "real-time, shadow algorithm", URL = "https://www.cg.tuwien.ac.at/research/publications/2005/Scherzer_2005/", } @inproceedings{Wimmer-2004-LSPM, title = "Light Space Perspective Shadow Maps", author = "Michael Wimmer and Daniel Scherzer and Werner Purgathofer", year = "2004", abstract = "In this paper, we present a new shadow mapping technique that improves the quality of perspective and uniform shadow maps. Our technique uses a perspective transform specified in light space which allows treating all lights as directional lights and does not change the direction of the light sources. This gives all the benefits of the perspective mapping but avoids the problems inherent in perspective shadow mapping like singularities in post-perspective space, missed shadow casters etc. Furthermore, we show that both uniform and perspective shadow maps distribute the perspective aliasing error that occurs in shadow mapping unequally over the available z-range. We therefore propose a transform that equalizes this error and gives equally pleasing results for near and far viewing distances. Our method is simple to implement, requires no scene analysis and is therefore as fast as uniform shadow mapping.", month = jun, isbn = "3-905673-12-6", publisher = "Eurographics Association", organization = "Eurographics", location = "Norrk\"{o}ping, Sweden", editor = "Alexander Keller and Henrik W. Jensen", booktitle = "Rendering Techniques 2004 (Proceedings Eurographics Symposium on Rendering)", pages = "143--151", keywords = "shadows, real-time rendering", URL = "https://www.cg.tuwien.ac.at/research/publications/2004/Wimmer-2004-LSPM/", }