Combining Rasterization and Ray Tracing Techniques to Approximate Global Illumination in Real-Time

With the advent of modern processing hardware, it became possible to bring global illumination effects into real-time applications. Namely, several classic global illumination algorithms were recently adapted to run in real-time on the GPU while ray tracing has also become suitable for real-time rendering on the CPU. Although none of these techniques provides a complete solution for simulating illumination in a realistic way, each one of them provides a different but complementary contribution for achieving this purpose. In this line of thought, this thesis introduces a 3D rendering engine that combines GPU rasterization and CPU ray tracing techniques in order to approximate global illumination in real-time. The engine simulates direct lighting using typical local illumination models while it simulates indirect lighting through an implementation of the light propagation volumes technique and a new sky lighting technique that is presented in this thesis which provides realistic indirect lighting for outdoor environments. These illumination effects are then complemented by sharp reflections and refractions generated by an hybrid real-time ray tracer that combines the processing power of the CPU and the GPU to generate these effects efficiently and to combine them seamlessly with the rest of the lighting.