Real-time rough refraction

We present an algorithm to render objects of transparent materials with rough surfaces in real-time, under distant illumination. Rough surfaces cause wide scattering as light enters and exits objects, which significantly complexifies the rendering of such materials. We present two contributions to approximate the successive scattering events at interfaces, due to rough refraction: First, an approximation of the bidirectional scattering function (BSDF = BRDF + BTDF), using spherical Gaussians, suitable for real-time estimation of environment lighting using pre-convolution; second, a combination of cone tracing and macro-geometry filtering to efficiently integrate the scattered rays at the exiting interface of the object. We demonstrate the quality of our approximation by comparison against stochastic raytracing.

[1]  R. Ramamoorthi,et al.  Frequency domain normal map filtering , 2007, SIGGRAPH 2007.

[2]  Pat Hanrahan,et al.  A signal-processing framework for inverse rendering , 2001, SIGGRAPH.

[3]  David K. McAllister,et al.  OptiX: a general purpose ray tracing engine , 2010, ACM Trans. Graph..

[4]  Steve Marschner,et al.  Microfacet Models for Refraction through Rough Surfaces , 2007, Rendering Techniques.

[5]  Michael Toksvig.  Mipmapping Normal Maps , 2005, J. Graph. Tools.

[6]  Hans-Peter Seidel,et al.  Light Field Techniques for Reflections and Refractions , 1999, Rendering Techniques.

[7]  Chris Wyman.  An approximate image-space approach for interactive refraction , 2005, ACM Trans. Graph..

[8]  Kun Zhou,et al.  Interactive Rendering of Non‐Constant, Refractive Media Using the Ray Equations of Gradient‐Index Optics , 2010, Comput. Graph. Forum.

[9]  Elmar Eisemann,et al.  Fast scene voxelization and applications , 2006, I3D '06.

[10]  Kun Zhou,et al.  Interactive relighting of dynamic refractive objects , 2008, SIGGRAPH 2008.

[11]  John Amanatides,et al.  Ray tracing with cones , 1984, SIGGRAPH.

[12]  Manuel Menezes de Oliveira Neto,et al.  Real-time refraction through deformable objects , 2007, SI3D.

[13]  John M. Snyder,et al.  All-frequency rendering of dynamic, spatially-varying reflectance , 2009, SIGGRAPH 2009.

[14]  Andreas Dietrich,et al.  OptiX: a general purpose ray tracing engine , 2010, SIGGRAPH 2010.

[15]  James F. Blinn,et al.  Models of light reflection for computer synthesized pictures , 1977, SIGGRAPH.

[16]  H. Seidel,et al.  Eikonal rendering: efficient light transport in refractive objects , 2007, SIGGRAPH 2007.

[17]  Pat Hanrahan,et al.  Frequency space environment map rendering , 2002, SIGGRAPH.

[18]  Kun Zhou,et al.  Interactive relighting of dynamic refractive objects , 2008, ACM Trans. Graph..

[19]  Hans-Peter Seidel,et al.  Eikonal rendering: efficient light transport in refractive objects , 2007, SIGGRAPH '07.

[20]  Baining Guo,et al.  The Dual‐microfacet Model for Capturing Thin Transparent Slabs , 2009, Comput. Graph. Forum.

[21]  Hans-Peter Seidel,et al.  Unified Approach to Prefiltered Environment Maps , 2000, Rendering Techniques.