Synthesis of Reflectance Function Textures from Examples

摘要: Abstract We extend the machinery of existing texture synthesis methods to handle images where each pixel contains not only RGB values, but reflectance functions. Like conventional methods, we can use photographs surface textures as examples base from. However multiple same are used characterize across lighting variation, and is based on these source images. Our approach performs directly in space functions does require any intermediate 3D reconstruction target surface. The resulting synthetic be rendered real-time with continuous control direction. 1. Introduction characterization real world surfaces an important aspect enabling photorealistic rendering. Early [Perlin 85, Peachy 85] relied ingenuity programmer develop procedural models that approximate appearance materials. Unfortunately, representation did lend itself automatic from photographs. This ability especially useful when new instantiations performed such a characterization. Powerful were developed late 80’s 90’s able synthesize samples photographic examples. Discussion found section 2.2. These have practical ramifications for computer graphics since they simplify mapping process several ways. First, larger patches produced, yielding more material process. Second, may synthesized periodic boundary conditions, producing seamlessly tiled, high image quality Although powerful, limitations address this paper. Since example input algorithms captured under specific conditions ‘baked in’. results will convincing those match patch finds object, general case. In fact, single map wrapped around even simple opposite sides object experience completely reversed directions local coordinate system map. Due spatial variation mesostructure microgeometry, modifications due changes illumination poorly approximated by attenuating intensity geometry. Figure 1 demonstrates behavior, rendering using light-dependent model compared modeled without dependency. Image-based re-lighting [Debevec 00, Malzbender 01, Ashikhmin 02, Debevec 02] provide solution quandary. approach, surface, person or taken varying static pose, characterizing changing constructed. With enough resolution spatially direction, very realistic renderings original produced arbitrary conditions. paper demonstrate how image-based polynomial maps (PTMs) [Malzbender 01] leveraged purposes synthesizing