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Perspective Shadow Maps

Perspective Shadow Maps. Marc Stamminger REVES/INRIA, Sophia-Antipolis, France now at: Bauhaus-Universität, Weimar, Germany George Drettakis REVES/INRIA, Sophia-Antipolis, France. Generate shadow. Kevin Weiler and Peter Atherton , Siggraph ‘ 19 7 7

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Perspective Shadow Maps

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  1. Perspective Shadow Maps Marc Stamminger REVES/INRIA, Sophia-Antipolis, France now at: Bauhaus-Universität, Weimar, Germany George Drettakis REVES/INRIA, Sophia-Antipolis, France

  2. Generate shadow • Kevin Weiler and Peter Atherton, Siggraph ‘1977 • Hidden Surface Removal Using Polygon Area Sorting • Franklin C., Siggraph ‘1977 • Shadow Algorithms for Computer Graphics

  3. shadow maps • Williams, Siggraph ‘1978 • render scene from light source • shadowing by depth comparison

  4. Adaptive shadow maps • T.Lokovic E.Vearch , Siggraph ‘2000 • Deep Shadow Maps • Randima F. Sebastian F. Kavita B., Siggraph ‘2001 • Adaptive Shadow Maps

  5. single shadow map pixel shadow map aliasing • prone to aliasingwhen zooming intoshadow boundaries

  6. okay aliased okay aliased shadow map aliasing • perspective aliasing parallel light

  7. shadow map aliasing • perspective aliasing • smooth transition aliased oversampled

  8. shadow map aliasing • projection aliasing parallel light

  9. shadow map aliasing • projection aliasing • very local aliased oversampled

  10. perspective transformation post-perspective world space

  11. standard shadow map perspective shadow map perspective shadow map shadow map image

  12. standard shadow map perspective shadow map perspective shadow map aliased oversampled

  13. perspective shadow map • shadow map in post-perspective space • just another shadow map projection • reduces perspective aliasing • regeneration per frame necessary

  14. light source transformation • parallellightbecomespointlight

  15. parallel light transformation post-perspective world space

  16. point light transformation post-perspective world space

  17. discussion • best case: • parallel light inpost-perspectivespace • no new perspectivedistortion post-perspective world space

  18. discussion • non-optimal case: • point lightclose tofrustum • worst case: • becomesuniformshadow map post-perspective world space

  19. near plane selection • near plane as far as possible

  20. near plane selection • automaticselection:reading backdepth buffer

  21. shadows from behind • virtuallymovecamerabackwards

  22. shadow map window • geometric method to include all necessary objects • details in the paper

  23. results

  24. results • first implementation on an Xbox game developer kit courtesy of Thatcher Ulrich

  25. conclusion • perspective shadow maps • shadow map in post-perspective space • just another shadow map matrix • non-uniform shadow map resolution • needs recomputation per frame • minimal overhead for dynamic scenes

  26. thank you

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