A hierarchical depth buffer for minimizing memory bandwidth in 3D rendering engine: Depth Filter

In this paper, we propose a new class of hierarchical depth test which saves memory bandwidth in 3D graphics rendering engine by reducing the number of pixels being passed to the per-pixel operation pipeline. This new filtering, Depth Filter, can be implemented by adding a simple hardware in front of the per-pixel operation pipeline. The Depth Filter is a filtering block which decides whether a pixel is shaded by certain plane. The plane is the mask which has the history that a pixel has appeared in front of the plane. If the pixel is shaded, the pixel can be removed. The simulation shows that Depth Filter reduces the number of pixels to the next stage up to 62.1 percent in random scene. As a result, 62.1% of memory bandwidth is saved with simple extra hardware.