Interactive virtual relighting of real scenes

摘要

Computer augmented reality (CAR) is a rapidly emerging field whichnenables users to mix real and virtual worlds. Our goal is to provideninteractive tools to perform common illumination, i.e., lightninteractions between real and virtual objects, including shadows andnrelighting (real and virtual light source modification). In particular,nwe concentrate on virtually modifying real light source intensities andninserting virtual lights and objects into a real scene; such changes cannbe very useful for virtual lighting design and prototyping. To achieventhis, we present a three-step method. We first reconstruct a simplifiednrepresentation of real scene geometry using semiautomatic vision-basedntechniques. With the simplified geometry, and by adapting recentnhierarchical radiosity algorithms, we construct an approximation of realnscene light exchanges. We next perform a preprocessing step, based onnthe radiosity system, to create unoccluded illumination textures. Thesenreplace the original scene textures which contained real light effectsnsuch as shadows from real lights. This texture is then modulated by anratio of the radiosity (which can be changed) over a display factornwhich corresponds to the radiosity for which occlusion has been ignored.nSince our goal is to achieve a convincing relighting effect, rather thannan accurate solution, we present a heuristic correction process whichnresults in visually plausible renderings. Finally, we perform anninteractive process to compute new illumination with modified real andnvirtual light intensities