Interactive Volumetric Shadows in Participating Media with Single-Scattering

Chris Wyman Shaun D. Ramsey
University of Iowa Washington College
Iowa City, IA Chestertown, MD
cwyman( ) email: shaun.ramsey( )

Proceedings of the IEEE Symposium on Interactive Ray Tracing, 87-92. August 2008.


Scattering effects arising from participating media, such as smoke, haze and fog, dramatically add to perceived realism in rendering. As shadows affect illumination throughout an environment, they significantly diminish scattering effects in umbral regions. Unlike surface shadowing, accurate volumetric shadows require simultaneously integrating illumination, scattering and attenuation throughout the volume, which proves challenging for interactive applications. We propose a method for rendering volumetric shadows in homogenous single scattering media that combines shadow volume and ray marching techniques, which eliminates performance deficiencies inherent in both. We extend this approach to interactively render shadows from textured lights and show results under two scattering models.

  • Full Paper in pdf
  • Interactive Volumetric Shadows in Participating Media with Single-Scattering.pdf
  • Appendix A
  • Refactoring Precomputation.pdf
  • Appendix B
  • Determining Ray Sampling Size.pdf
  • GLSL Shader from Appendix A
  • shader.frag.glsl
  • Talk at IRT 08
  • IRT08 Talk.pdf


  • Backlit Bunny (14M)
  • Backlit_Bunny.divx.avi
  • Bouncing Ball (19M)
  • Bouncing_Ball.divx.avi
  • Comparison (26M)
  • Yeah_Right.divx.avi

    Demo and Exe

  • Volumetric Shadows Demo
  • Volumetric Shadows Demo Executable