@misc{brugger-2020-tdp, title = "Test Scene Design for Physically Based Rendering", author = "Elias Brugger and Christian Freude and Michael Wimmer", year = "2020", abstract = "Physically based rendering is a discipline in computer graphics which aims at reproducing certain light and material appearances that occur in the real world. Complex scenes can be difficult to compute for rendering algorithms. This paper introduces a new comprehensive test database of scenes that treat different light setups in conjunction with diverse materials and discusses its design principles. A lot of research is focused on the development of new algorithms that can deal with difficult light conditions and materials efficiently. This database delivers a comprehensive foundation for evaluating existing and newly developed rendering techniques. A final evaluation compares different results of different rendering algorithms for all scenes.", month = aug, URL = "https://www.cg.tuwien.ac.at/research/publications/2020/brugger-2020-tdp/", } @techreport{freude_2020_rs, title = "R-Score: A Novel Approach to Compare Monte Carlo Renderings", author = "Christian Freude and Hiroyuki Sakai and Karoly Zsolnai-Feh\'{e}r and Michael Wimmer", year = "2020", abstract = "In this paper, we propose a new approach for the comparison and analysis of Monte Carlo (MC) rendering algorithms. It is based on a novel similarity measure called render score (RS) that is specically designed for MC rendering, statistically motivated, and incorporates bias and variance. Additionally, we propose a comparison scheme that alleviates the need for practically converged reference images (RIs). Our approach can be used to compare and analyze dierent rendering methods by revealing detailed (per-pixel) dierences and subsequently potential conceptual or implementation-related issues, thereby offering a more informative and meaningful alternative to commonly used metrics.", month = aug, number = "TR-193-02-2020-4", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", institution = "Research Unit of Computer Graphics, Institute of Visual Computing and Human-Centered Technology, Faculty of Informatics, TU Wien ", note = "human contact: technical-report@cg.tuwien.ac.at", URL = "https://www.cg.tuwien.ac.at/research/publications/2020/freude_2020_rs/", } @article{Jimenez_SSS_2015, title = "Separable Subsurface Scattering", author = "Jorge Jimenez and Karoly Zsolnai-Feh\'{e}r and Adrian Jarabo and Christian Freude and Thomas Auzinger and Xian-Chun Wu and Javier van der Pahlen and Michael Wimmer and Diego Gutierrez", year = "2015", abstract = "In this paper we propose two real-time models for simulating subsurface scattering for a large variety of translucent materials, which need under 0.5 milliseconds per frame to execute. This makes them a practical option for real-time production scenarios. Current state-of-the-art, real-time approaches simulate subsurface light transport by approximating the radially symmetric non-separable diffusion kernel with a sum of separable Gaussians, which requires multiple (up to twelve) 1D convolutions. In this work we relax the requirement of radial symmetry to approximate a 2D diffuse reflectance profile by a single separable kernel. We first show that low-rank approximations based on matrix factorization outperform previous approaches, but they still need several passes to get good results. To solve this, we present two different separable models: the first one yields a high-quality diffusion simulation, while the second one offers an attractive trade-off between physical accuracy and artistic control. Both allow rendering subsurface scattering using only two 1D convolutions, reducing both execution time and memory consumption, while delivering results comparable to techniques with higher cost. Using our importance-sampling and jittering strategies, only seven samples per pixel are required. Our methods can be implemented as simple post-processing steps without intrusive changes to existing rendering pipelines. https://www.youtube.com/watch?v=P0Tkr4HaIVk", month = jun, journal = "Computer Graphics Forum", volume = "34", number = "6", issn = "1467-8659", pages = "188--197", keywords = "separable, realtime rendering, subsurface scattering, filtering", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/Jimenez_SSS_2015/", } @mastersthesis{Freude_MSc, title = "Extending Separable Subsurface Scattering to Arbitrary Materials", author = "Christian Freude", year = "2015", abstract = "This thesis proposes extensions for the Separable Subsurface Scattering algorithm to support arbitrary materials. Four separable (rank-1) kernel models for the approximation of physically based diffuse reflectance profiles are presented. Each model offers different approximation quality and controllability. The first two models are based on singular value decomposition and a custom analytic pre-integration scheme. They enable fast deterministic kernel computation and provide fixed-quality solutions. Two additional parametrized models are based on automatic and manual optimization and provide more control over the approximation quality but are more time-consuming to generate. Higher rank approximations can be computed using the approach based on singular value decomposition. All four kernel models are used to compute approximations for physically measured diffuse reflectance profiles of different materials and tested using several special-case irradiance signals and complex proof-of-concept scenes. The results are compared to the state of the art in realtime rendering of subsurface scattering, showing comparable approximation quality at lower computational cost. The proposed extensions enable rendering of physically based subsurface scattering for arbitrary materials and dynamic scenes in real time. https://www.youtube.com/watch?v=P0Tkr4HaIVk", month = jan, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "subsurface scattering, real-time", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/Freude_MSc/", } @xmascard{freude-2015-xmc, title = "X-Mas Card 2015", author = "Christian Freude", year = "2015", abstract = "This greeting card shows the branch of a Christmas tree which is decorated with a candle as well as the logos of our institute and the TU Wien. For a realistic representation of Subsurface Scattering in the candle and the pine needles, a method called Separable Subsurface Scattering was used, which was developed in cooperation with our institute. This image was calculated in real time, with the additional use of HDR rendering and depth-of-field. Only the frost effect and the flame of the candle were added later using GIMP. The images on the right show additional examples of the used Subsurface Scattering technique. Diese Gru{\ss}karte zeigt den Ast eines Christbaums welcher mit einer Kerze sowie den Logos des Instituts und der TU Wien dekoriert ist. Um eine m\"{o}glichst realistische Darstellung von Subsurface Scattering in der Kerze sowie den Tannennadeln zu erzielen, wurde eine Methode namens Separable Subsurface Scattering verwendet, welche in Kooperation mit unserem Institut entwickelt wurde. Dieses Bild wurde in Echtzeit berechnet, unter zus\"{a}tzlicher Verwendung von HDR Rendering und Tiefenunsch\"{a}rfe. Lediglich der Frost-Effekt sowie die Flamme der Kerze wurden nachtr\"{a}glich mittels GIMP hinzugef\"{u}gt. Die Bilder auf der rechten Seite zeigen weitere Beispiele der verwendeten Subsurface Scattering Technik.", keywords = "X-Mas Card", URL = "https://www.cg.tuwien.ac.at/research/publications/2015/freude-2015-xmc/", }