Evaluation of Object-Space Occlusion Culling with Occluder Fusion

Abstract: In this report, an object-space solution to occluder fusion of OBB occluders is explored. Two different approaches are considered were the object-space fusion is reduced to a 2D problem. The first approach finds axis-aligned silhouettes within the projection of occluder OBBs which are then fused together creating large axis-aligned silhouettes. The other approach creates concave hulls of the projected OBB silhouettes from which convex inscribed silhouettes are then found. These silhouettes are then converted back to object-space where shadow frusta created around the silhouettes are used for the culling operation. The effectiveness of the two approaches is evaluated considering the amount of culled geometry. It is shown that fused convex silhouettes are needed to produce competitive results.