Hierarchical Occluders for Interactive Rendering of Large Models

Project Update 1
Project Update 2
Final Presentation
Final Report

Goal

I plan to determine a heirarchy of occluders for use in Occlusion Culling, and incorporate it into the present interactive walkthru system developed at UNC. The final goal is to incorporate a form of hierarchical Z-buffers with an HLOD system.
 

Motivation

A large portion of the time in rendering a scene is spent on determining the visibility. Simple hardware based z-buffer tests do not suffice for rendering large models in real time. Several methods exist for speeding up the rendering by quickly determining the visibility information. Hierarchical Occlusion along with LOD rendering techniques offer scope for achieving interactive rates on large models.
 

Personal Interest

I like working on geomteric problems and interactive graphics. This project also blends well with my current research interests.
 

Previous Work

Many recent methods try to exploit object-space, image-space and temporal coherence for accelerating visiblity computations. Some methods :

Greene et al proposed the Heirarchical Z-Buffer Visibility algorithm that maintains the scenemodel in an
octreeand the z-buffer in an image  pyramid.

Zhang and Manocha compute a Hierarchical Occlusion Map of foreground occluders and use that for culling during rendering.

Erikson and Manocha compute HLOD for nodes in the scene graph and use them for simplification culling - ie ignore portions o the scene grpah by using HLODs. This speeds up rendering, however HLODs are not an accurate estimate for determining occluders.

Demonstration

The Power Plant model (~15 million triangles) at 20fps and then attack the Double Eagle model (~80 million traingles)