Real time volumetric shadows using polygonal light volumes

This paper presents a more efficient way of computing single scattering effects in homogeneous participating media for real-time purposes than the currently popular ray-marching based algorithms. These effects include halos around light sources, volumetric shadows and crepuscular rays. By displacing the vertices of a base mesh with the depths from a standard shadow map, we construct a polygonal mesh that encloses the volume of space that is directly illuminated by a light source. Using this volume we can calculate the airlight contribution for each pixel by considering only points along the eye-ray where shadow-transitions occur. Unlike previous ray-marching methods, our method calculates the exact airlight contribution, with respect to the shadow map resolution, at real time frame rates. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism--Color, shading, shadowing and texture

• Type: Journal
• Year: 2010
• Where: EGH
• Authors: Markus Billeter, Erik Sintorn, Ulf Assarsson
• Keywords: Airlight Contribution, Computer Graphics, EGH 2010, Light Source, Shadow Map