Rendering Microgeometry with Volumetric Precomputed Radiance Transfer

Although computer graphics hardware has made tremendous advances over the last few years, there are many things which are still not feasible to render in realtime. One of these is the subset of surfaces referred to as ’microgeometry,’ where many small individual pieces combine to create a complex surface. Microgeometry is a problem for typical polygonal rendering systems, the method used in the vast majority of realtime rendering, because of the large number of triangles needed to accurately represent microgeometry and the complex optical effects that these surfaces can possess. I propose a new technique for rendering microgeometry in realtime with realistic lighting effects through a unique combination of realtime and offline rendering methods. It consists of a volumetric microgeometry rendering system based upon the Texel rendering method [Kajiya and Kay 1989], a concentric shell surface rendering method [Lengyel et al. 2001], an approximation of global illumination based upon Precomputed Radiance Transfer [Sloan et al. 2002], and a local lighting model.