Real-Time Occlusion Culling with a Lazy Occlusion Grid

We present a new conservative image-based occlusion culling method to increase the speed of hardware accelerated rendering of very complex general scenes which may consist of millions of polygons without time-expensive preprocessing. The method is based on a lowresolution grid upon a conventional z-buffer or an occlusion-buffer. This grid is updated in a lazy manner which reduces the number of expensive occlusion queries at pixel-level significantly compared to a busy update. It allows fast decisions if an object is occluded or potentially visible. The grid is used together with a bounding volume hierarchy that is traversed in a front to back order and which allows to cull large parts of the scene at once. We show that the method works efficiently on today ́s available hardware and we compare lazy and busy updates.