Using Perception-Based Filtering to Hide Shadow Artifacts

Information

• Publication Type: Master Thesis
• Workgroup(s)/Project(s):
  • Rendering and Modeling
• Date: October 2017
• Date (Start): 1. June 2016
• Date (End): 5. October 2017
• Diploma Examination: 5. October 2017
• First Supervisor:
  • Michael Wimmer
  • Michael Hecher
• Keywords: soft shadows

Abstract

Shadows are an indispensable aid for understanding spatial relations of objects in natural scenes, which is why they are very important for real-time rendering applications. Combining filtering techniques with shadow mapping is a common tool to simulate visually-pleasing shadows in interactive applications. A positive effect of such approaches is that the filtering blurs aliasing artifacts caused by sampling the discretized geometric data stored in the shadow map, thereby improving the visual quality of the shadow. The goal of this thesis is to exploit common filtering algorithms, in order to find a function of blur radius and shadow-map sampling frequency, which allows for optimized computational performance while mostly preserving the visual quality of the shadow. In the course of this work, we investigate how shadow artifacts arise and how to hide them. We set up and execute a user study to find the optimal relation between the shadow-map sampling frequency and the filter radius. From the results of the user study, we derive a formula and develop an algorithm that can be incorporated into existing shadow-mapping algorithms. We evaluate our results by applying the algorithm to a custom-made rendering framework and observe an increase in processing speeds.

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BibTeX

@mastersthesis{KREUZER-2017-PBF,
  title =      "Using Perception-Based Filtering to Hide Shadow Artifacts",
  author =     "Felix Kreuzer",
  year =       "2017",
  abstract =   "Shadows are an indispensable aid for understanding spatial
               relations of objects in natural scenes, which is why they
               are very important for real-time rendering applications.
               Combining filtering techniques with shadow mapping is a
               common tool to simulate visually-pleasing shadows in
               interactive applications. A positive effect of such
               approaches is that the filtering blurs aliasing artifacts
               caused by sampling the discretized geometric data stored in
               the shadow map, thereby improving the visual quality of the
               shadow. The goal of this thesis is to exploit common
               filtering algorithms, in order to find a function of blur
               radius and shadow-map sampling frequency, which allows for
               optimized computational performance while mostly preserving
               the visual quality of the shadow. In the course of this
               work, we investigate how shadow artifacts arise and how to
               hide them. We set up and execute a user study to find the
               optimal relation between the shadow-map sampling frequency
               and the filter radius. From the results of the user study,
               we derive a formula and develop an algorithm that can be
               incorporated into existing shadow-mapping algorithms. We
               evaluate our results by applying the algorithm to a
               custom-made rendering framework and observe an increase in
               processing speeds.",
  month =      oct,
  address =    "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
  school =     "Institute of Computer Graphics and Algorithms, Vienna
               University of Technology ",
  keywords =   "soft shadows",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2017/KREUZER-2017-PBF/",
}