Screen Space Photon Mapping Revisited

Abstract

This is the master thesis project performed by Reinier van Oeveren under supervision of dr. M. Wand and dr. J. Bikker at Utrecht University. Global illumination algorithms are a widely studied subject in the ?eld of computer graphics. Their goal is to evaluate the direct and indirect illumination in a scene. The rendering equation describes how light transport works mathematically. Algorithms such as photon mapping are designed to solve the rendering equation. The ?rst part of the thesis consists of an in-depth survey into the details of global illumination, such as technical background and well- known algorithms. For the second part of this thesis we propose and implement a hybrid photon mapping method that turns nearest neighbor searches into screen space operations. In addition, we explore whether our adapted screen space approach to mipmapping, the pull-push ?lter, is a valid alternative to conventional nearest neighbor searches. We evaluate our method in terms of photon gathering and rendering using an elaborate series of experiments. We show that our method is capable of producing images with a quality that is at least equal to that of standard photon mapping.