Microfacet Billboarding

Abstract

Rendering of intricately shaped objects that are soft or cluttered is difficult because we cannot accurately acquire their complete geometry. Since their geometry varies drastically, modeling them using fixed facets can lead to severe artifacts when viewed from singular directions. In this paper, we propose a novel modeling method, "microfacet billboarding", which uses view-dependent "microfacets" with view-dependent textures. The facets discretely approximate the geometry of the object and are aligned perpendicular to the viewing direction. The texture of each facet is selected from the most suitable texture images according to the viewpoint. Microfacet billboarding can render intricate geometry from various viewpoints. We first describe the basic algorithm of microfacet billboarding. Also, we predict artifacts generated due to the use of discrete facets and we analyze the necessary sampling interval of the geometry and texture for regarding the artifacts as negligible. In addition to the modeling method, we have implemented a real-time renderer by a hardware-accelerated technique. To evaluate the efficiency of our method, we compared it with traditional texture mapping to a mesh model, and showed that our method has a great advantage over the former in rendering intricately shaped objects.