How can unnecessary geometry redraws can be avoided using Occlusion predicate query?

Traditionally vertex processing and geometry redraws were unavoidable, even when the meshes in the viewing frustum were occluded [hidden] by other meshes. Direct3D 10 introduced D3D10_QUERY_OCCLUSION_PREDICATE query type which allows a drawing operation to succeed or fail based upon whether pixels from a previous draw operation were visible. As the predicate query is created with D3D10_QUERY_MISC_PREDICATEHINT, the result of the query can be used to draw or not draw geometry without waiting for the result to be transferred from the GPU to the CPU. For complex high resolution meshes a low resolution occlusion mesh [created specifically for occlusion purpose or a collision mesh] is used. The GPU compares whether the high resolution mesh needs to be drawn by applying the occlusion predicate query on the occlusion mesh without the intervention of CPU and thus removes the additional vertex processing cost.

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