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What is GPU occlusion culling?
Occlusion culling is a rendering optimisation technique that refers to not drawing triangles (meshes in general) that will not be visible on screen due to being occluded by (i.e. they are behind) some other solid geometry. There are ways to avoid pixel shader work for occluded triangles.
What is hierarchical Z buffer occlusion?
Hierarchical-Z is a well known and standard feature of modern GPUs that allows them to speed up depth testing by rejecting large group of incoming fragments using a reduced and compressed version of the depth buffer that resides in on-chip memory.
When to use Z buffering for occlusion culling?
When the nearby object is rendered it would set a pixel somewhere on a lower-resolution level of the Z buffer pyramid to a near depth value. When a farther smaller object is being rendered, its bounding box can first be checked against that pixel and be culled in its entirety. Yes. It’s the same octrees.
Which is an example of hierarchical Z buffering?
Hierarchical Z-buffer is useful in situations when large nearby objects are likely to occlude a lot of small farther objects. An example would be rendering an inside of a building or a mountainous landscape. When the nearby object is rendered it would set a pixel somewhere on a lower-resolution level of the Z buffer pyramid to a near depth value.
When do you use hierarchical depth buffers in graphics?
Hierarchical depth (also known as Hi-Z) is a technique that comes up often in graphics. It’s used to accelerate occlusion culling (on the CPUand theGPU), screen-space reflections, screen-space ambient occlusion, volumetric fog, and more. Additionally, it’s common for GPUs to implement Hi-Zas part of the rasterization pipeline.
How to avoid edge cases with Hi-Z culling?
Before attempting any kind of Hi-Z culling, we first attempt to frustum cull the instance. Frustum culling is implemented very efficiently (especially for bounding spheres), and by frustum culling, we also avoid some edge cases with the Hi-Z algorithm later.