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.
Heinrich Hey, Robert F. Tobler, Werner Purgathofer