Rouslan Dimitrov

Image-space horizon-based ambient occlusion

Ambient occlusion is a lighting model that approximates the amount of light reaching a point on a diffuse surface based on its directly visible occluders. It gives perceptual clues of curvature and spatial proximity. Like [Mittring 2007] and [Shanmugam and Arikan 2007], we propose a real-time ambient occlusion computation as a postprocessing pass mainly based on a depth image from the eye’s point of view. This approach requires no scenedependent precomputations and is applicable to dynamic scenes. Our proposed method does not have the overocclusion issue from [Shanmugam and Arikan 2007] and samples inside the radius of influence, unlike [Mittring 2007].

Horizon-split ambient occlusion

The method includes receiving a plurality of graphics primitives for rendering at a GPU of a computer system and rendering graphics primitives into pixel parameters of the pixels of a display, wherein the parameters include pixel depth values and pixel normal values. For each pixel of the display, an ambient occlusion process is performed. The algorithm takes as input a ND-buffer containing pixel depth values and pixel normals. Based on the pixel 3-D position and the pixel normal vector, horizon heights are computed by sampling the ND-buffer and an occlusion term is computed for each pixel based on the horizon heights. Based on the pixel 3-D position, the pixel normal vector, a normal occlusion term is computed by sampling the ND-buffer above the horizon in multiple directions. An ambient occlusion illumination value is computed by combining the horizon occlusion term and the normal occlusion term.