Multiple Strategy Stochastic Iteration for Architectural Walkthroughs

Information

• Publication Type: Technical Report
• Workgroup(s)/Project(s): not specified
• Date: July 2001
• Number: TR-186-2-01-17
• Keywords: Monte-Carlo methods, finite-element techniques, stochastic iteration, Global illumination

Abstract

Architectural walkthroughs require fast global illumination algorithms and also accurate results from certain viewpoints. This paper introduces a global illumination method that combines several strategies to meet the contradicting criteria of architectural walkthroughs. The methods include parallel and perspective ray-bundle shooting and ray shooting. Each method is designed to randomly approximate the effect of the light transport operator. Parallel ray-bundle tracing transfers the radiance of all points parallel to a randomly selected global direction, with perspective ray-bundles we can shoot the radiance of a single patch in all directions, and ray shooting transfers the radiance of a randomly selected point at a randomly selected direction. These strategies are of complementary character since each of them is effective in different illumination conditions. The proposed algorithm is iterative and the steps realized by different methods that randomly follow each other. In each step, the applied strategy is selected randomly according to the properties of the current radiance distribution, thus we can exploit that the used strategies are good in different conditions. The formal framework of their combination is the stochastic iteration. Although the final result is the image, i.e. the algorithm is view dependent, a rough approximation of the radiance function is stored in object space, that can allow fast movements at reasonable storage requirements and also speed up Monte-Carlo simulations which result in the final image. The method is also suited for interactive walkthrough animation in glossy scenes since when the viewpoint changes, the object space radiance values remain valid and the image quickly adapts to the new situation.

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BibTeX

@techreport{Szirmay-2001-MSTI,
  title =      "Multiple Strategy Stochastic Iteration for Architectural
               Walkthroughs",
  author =     "L\'{a}szl\'{o} Szirmay-Kalos and Gyorgy Antal and Ferenc
               Csonka and Csaba Kelemen",
  year =       "2001",
  abstract =   "Architectural walkthroughs require fast global illumination
               algorithms and also accurate results from certain
               viewpoints. This paper introduces a global illumination
               method that combines several strategies to meet the
               contradicting criteria of architectural walkthroughs. The
               methods include parallel and perspective ray-bundle shooting
               and ray shooting. Each method is designed to randomly
               approximate the effect of the light transport operator.
               Parallel ray-bundle tracing transfers the radiance of all
               points parallel to a randomly selected global direction,
               with perspective ray-bundles we can shoot the radiance of a
               single patch in all directions, and ray shooting transfers
               the radiance of a randomly selected point at a randomly
               selected direction. These strategies are of complementary
               character since each of them is effective in different
               illumination conditions. The proposed algorithm is iterative
               and the steps realized by different methods that randomly
               follow each other. In each step, the applied strategy is
               selected randomly according to the properties of the current
               radiance distribution, thus we can exploit that the used
               strategies are good in different conditions. The formal
               framework of their combination is the stochastic iteration.
               Although the final result is the image, i.e. the algorithm
               is view dependent, a rough approximation of the radiance
               function is stored in object space, that can allow fast
               movements at reasonable storage requirements and also speed
               up Monte-Carlo simulations which result in the final image.
               The method is also suited for interactive walkthrough
               animation in glossy scenes since when the viewpoint changes,
               the object space radiance                   values remain
               valid and the image quickly adapts to the new situation.",
  month =      jul,
  number =     "TR-186-2-01-17",
  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 =   "Monte-Carlo methods, finite-element techniques, stochastic
               iteration, Global illumination",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2001/Szirmay-2001-MSTI/",
}