Radiance Interpolants for Interactive Scene Editing and Ray Tracing by

Ray tracers are usually regarded as off-line rendering algorithms that are too slow for interactive use. This thesis introduces techniques to accelerate ray tracing and to support interactive editing of ray-traced scenes. These techniques should be useful in many applications, such as architectural walk-throughs, modeling, and games, and will enhance both interactive and batch rendering. This thesis introduces radiance interpolants: radiance samples that can be used to rapidly approximate radiance with bounded approximation error. Radiance interpolants capture object-space, ray-space, image-space and temporal coherence in the radiance function. New algorithms are presented that efficiently, accurately and conservatively bound approximation error. The interpolant ray tracer is a novel renderer that uses radiance interpolants to accelerate both primary operations of a ray tracer: shading and visibility determination. Shading is accelerated by quadrilinearly interpolating the radiance samples associated with a radiance interpolant. Determination of the visible object at each pixel is accelerated by reprojecting interpolants as the user's viewpoint changes. A fast scan-line algorithm then achieves high performance without sacrificing image quality. For a smoothly varying viewpoint, the combination of lazily sampled interpolants and reprojection substantially accelerates the ray tracer. Additionally, an efficient cache management algorithm keeps the memory footprint of the system small with negligible overhead. The interpolant ray tracer is the first accelerated ray tracer that reconstructs radiance from sparse samples while bounding error conservatively. The system controls error by adaptively sampling at discontinuities and radiance non-linearities. Because the error introduced by interpolation does not exceed a user-specified bound, the user can trade performance for quality. The interpolant ray tracer also supports interactive scene editing with incremental rendering; it is the first incremental ray tracer to support both object manipulation and changes to the viewpoint. A new hierarchical data structure, called the ray segment tree, tracks the dependencies of radiance interpolants on regions of world space. When the scene is edited, affected interpolants are rapidly identified and updated by traversing these ray segment trees. Acknowledgments There are many people I should thank for supporting me through my Ph.D. First, I would like to thank my advisors, Prof. Seth Teller and Prof. Julie Dorsey, who gave me a chance; I entered the field of graphics four years ago with no prior experience, and they took me on and were patient as I learned the ropes. Working with them has been a wonderful learning experience; I have benefited greatly from their knowledge of the …