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Imperfect Shadow Maps

Tobias Ritschel1     Thorsten Grosch1     Min H. Kim2     Hans-Peter Seidel1     Carsten Dachsbacher3     Jan Kautz2

1MPI Informatik     2UCL London     3Universität Stuttgart    

Paper Abstract

We present a method for interactive computation of indirect illumination in large and fully dynamic scenes based on approximate visibility queries. While the high-frequency nature of direct lighting requires accurate visibility, indirect illumination mostly consists of smooth gradations, which tend to mask errors due to incorrect visibility. We exploit this by approximating visibility for indirect illumination with imperfect shadow maps—low-resolution shadow maps rendered from a crude point-based representation of the scene. These are used in conjunction with a global illumination algorithm based on virtual point lights enabling indirect illumination of dynamic scenes at real-time frame rates. We demonstrate that imperfect shadow maps are a valid approximation to visibility, which makes the simulation of global illumination an order of magnitude faster than using accurate visibility.

Materials for Download

The paper (Adobe Acrobat PDF, 3.8 MB).
The high-resolution paper (Adobe Acrobat PDF, 14.2 MB).
The supplemental video (Windows AVI, 26.9 MB).
SIGGRAPH Asia '08 talk slides (zipped MS PowerPoint, 24.5 MB)
Please note: YouTube only gives a preview of the effect but doesn't reproduce it in professional quality. For full quality, please download the supplemental material .AVI video (26.9 MB).


Tobias Ritschel, Thorsten Grosch, Min H. Kim, Hans-Peter Seidel, Carsten Dachsbacher, Jan Kautz
Imperfect Shadow Maps for Efficient Computation of Indirect Illumination
ACM Trans. Graph. 27(5) (Proceedings SIGGRAPH Asia 2008), 2008.

   author  = {Tobias Ritschel and 
              Thorsten Grosch and 
              Min H. Kim and 
              Hans-Peter Seidel and 
              Carsten Dachsbacher and 
              Jan Kautz},
   title   = {{Imperfect Shadow Maps for Efficient Computation of Indirect Illumination}},
   journal = {ACM Trans. Graph. (Proc. of SIGGRAPH ASIA 2008)},
   volume  = 27,
   number  = 5,
   year    = {2008}

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