Conservative and Tiled Rasterization Using a Modified Triangle Set-Up

Several algorithms that use graphics hardware to accelerate processing require conservative rasterization in order to function correctly. Conservative rasterization stands for either overestimating or underestimating the size of the triangles. Overestimation is carried out by including all pixels that are at least partially overlapped by the triangle, whereas underestimation includes only the pixels that are fully inside the triangle. None or few algorithms for conservative rasterization have been described in the literature, and current hardware does not explicitly support it. Therefore, we present a simple algorithm, which requires only a small modification to the triangle setup when edge functions are used. Furthermore, the same algorithm can be used for tiled rasterization, where all pixels in a tile (e.g. 8× 8 pixels) are visited before moving to the next tile.