WPI Major Qualifying Project


Methods of Global Illumination, which model inter-reflections between objects in a scene, are key to creating realistic images.

A recent technique that approximates Global Illumination is Light Propagation Volumes (LPV), which runs at interactive frame rates, or `realtime'. This report details the design and implementation of a realtime Global Illumination approximation using LPV's, simulating both reflected and transmitted diffuse light.

It employs 4th degree polynomial Spherical Harmonics on separate color channels to represent the flow of light, and its complexity is independent of resolution or geometry. A modular framework using OpenGL version 3.3 was built to support the task and implements a deferred rendering system to facilitate the multiple passes required by the technique employed. A Reflective Shadow Map is used to build a model of the lighting environment inside the LPV, which is then processed to propagate light through the scene.

The program runs at an average of 40 FPS on modern graphics hardware and uses less than 50MB of system memory and 70MB of GPU memory, making it a viable option for realtime rendering applications.

The scene displayed is a leafy bush and ground plate, textures painted in Photoshop, model made in Blender.

Download the entire paper: pdf

Demo Video

Final Composite