US Patent 7289119 Statistical rendering acceleration

Different rendering techniques are selected for portions of a scene based on statistical estimates of the portions' rendering costs. A scene is partitioned into a bounding volume hierarchy. Each bounding volume includes a statistical model of the spatial distribution of geometric primitives within the bounding volume. An image to be rendered is partitioned into screen regions and each screen region is associated with one or more bounding volumes and their statistical models. The associated statistical models of a screen region are evaluated to estimate the rendering cost, such as the probable number of geometric primitives per pixel, for the screen region. Based on the rendering cost, the screen region is assigned to a dense geometry renderer, such as a ray tracing renderer, or a sparse geometry renderer, such as a rasterization renderer. Rendered screen regions are combined to form a rendered image.