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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 http://www-sop.inria.fr/reves. shadow maps. Williams, Siggraph ‘78 render scene from light source

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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 http://www-sop.inria.fr/reves

  2. shadow maps • Williams, Siggraph ‘78 • render scene from light source • shadowing by depth comparison

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

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

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

  6. shadow map aliasing • projection aliasing parallel light

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

  8. previous work • Reeves et al., Siggraph ’87: • “Percentage Closer Filtering” • Tadamura et al., Visual Computer ’01 • “Plural Sunlight Depth Buffers” • Fernando et al., Siggraph ’01: • “Adaptive Shadow Maps”

  9. perspective transformation post-perspective world space

  10. standard shadow map perspective shadow map perspective shadow map shadow map image

  11. standard shadow map perspective shadow map perspective shadow map aliased oversampled

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

  13. light source transformation • parallellightbecomespointlight

  14. parallel light transformation post-perspective world space

  15. point light transformation post-perspective world space

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

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

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

  19. near plane selection • automaticselection:reading backdepth buffer

  20. shadows from behind • virtuallymovecamerabackwards

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

  22. results

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

  24. 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

  25. acknowledgements • Marie Curie Post-Doctoral Fellowship of the European Union • Bauhaus-Universität Weimar • Lutz Kettner (http://www.cgal.org) • Frédo Durand

  26. thank you http://www-sop.inria.fr/reves

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