Abstract
Ambient Occlusion (AO) is a widely used shadowing technique in 3D rendering. One of the main disadvantages of using it is that it requires not only the surface depth but also the normal vector, which usually causes severe aliasing. This work introduces a novel AO algorithm by applying Chebyshev’s inequality. Instead of requiring the normal vector, we process the mean ( $\mu $ ) of the distribution of depth values from the screen space. We can efficiently calculate the variance ( $\sigma ^{2}$ ) over any kernel region. Using the Chebyshev AO, we can get the upper bound on the percentage of the shaded surface that is occluded. Our proposed method can usually provide a good approximation of true occlusion and can be used as an approximate value for AO rendering. As a post-processing rending, the time complexity of Chebyshev AO is $O\left ({2k}\right)$ which is simple to implement on current graphics devices and can be applied to the next generation of ray tracing technology.
Highlights
Local illumination is usually used in real-time rendering, making it difficult to carry out the requirements of 3D vision
Ambient Occlusion (AO) rendering considers objects within a certain radius and assumes that the wall is the origin of the ambient light
[6] introduces the Horizon Based Ambient Occlusion (HBAO), which is an enhanced Screen Space Ambient Occlusion (SSAO) based on the horizon in the 3D scene
Summary
Local illumination is usually used in real-time rendering, making it difficult to carry out the requirements of 3D vision. RELATED WORK considering that shadows are too demanding on graphics for many games with dynamic scenes, AO still needs a lot of calculations to achieve its sampling steps To achieve this in real-time, one approach proposes to achieve the sampling of the depth buffer based on the current screen space, instead of the 3D scene space [4]. [6] introduces the Horizon Based Ambient Occlusion (HBAO), which is an enhanced SSAO based on the horizon in the 3D scene This approach solves the grain and noise caused by SSAO pixel depth measurement by considering the ambient and the environment instead of the depth buffer only, but it requires more processing power in the CPUs and in the GPUs. Later, [7] proposed to use a mixture of the HBAO sampling from multi-viewport screen space, which achieves a better render result but requires heavy computation. Since k is independent of the size of the scene, it can more effectively enhance the parallelism used by the GPUs while introducing dynamic rendering to make the ambient more realistic
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