Enabling Increased Complexity for Realistic Image Synthesis

This dissertation discusses work that enables the realistic image synthesis of very complex scenes. Some of the work herein describes approaches for modeling more complicated scenes, while other portions describe algorithms for accelerating the rendering of complex scenes. First we propose a simple method for modeling and rendering refractive objects that are nested within each other. The technique allows the use of simpler scene geometry and can even improve rendering time in some images. The algorithm can be easily added into an existing ray tracer and makes no assumptions about the drawing primitives that have been implemented. This allows for arbitrary nesting of dielectric objects while still maintaining correctness of refraction. This technique makes such a modeling task fairly trivial compared to what modelers typically endure to allow these effects. A complementary technique described in this dissertation enables fast unbiased rendering of caustics, an effect that occurs when light bounces off of shiny objects and hits diffusive objects. The method uses importance-sampled Path Tracing with Caustic Forecasting. The technique is part of a straightforward rendering scheme that extends the Illumination by Weak Singularities method to allow fully unbiased global illumination with rapid convergence. A photon shooting preprocess, similar to that used in Photon Mapping, generates photons that interact with specular geometry. These photons are then clustered, effectively dividing the scene into regions contributing similar amounts of caustic lighting to the image. Finally, the photons are stored into spatial data structures associated with each cluster, and the clusters themselves are organized into a spatial data structure for fast searching. During rendering, clusters are used to decide the caustic energy importance of a region, and use the local photons to aid in importance sampling, effectively reducing the number of samples required to capture caustic lighting. We also investigate the RBSP, an acceleration structure related to k-d trees and BSP trees,