Non-Uniform Frame Buffer Rasterization for VR Pixel Efficiency
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Solution Overview
Problem
Rendering for both eyes in virtual reality head-mounted displays doubles the load on graphics processors and involves significant redundant work due to warping rectangular images, leading to inefficient pixel density utilization.
Innovation Solution
Implementing non-uniform frame buffer rasterization techniques that vary pixel density based on the image's position, positioning higher resolution tiles towards the center and using tiles of different resolutions stored in memory pages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If regular planar projection techniques are used to generate warped images for head-mounted displays, then the images can be rendered with uniform pixel density, but significant redundant work is performed with low pixel density utilization at the edges and corners
Solution Approach 1:
The patent applies local quality by varying the pixel density across different regions of the intermediate image. Specifically, higher pixel density is maintained in the central region where it is most useful, while lower pixel density is used in the edge and corner regions where pixels are sparse after warping. This is achieved through a non-uniform rasterization process that adjusts the spacing between rendered pixels based on their position in the image, thereby optimizing the distribution of rendering resources to match the actual useful pixel density after the warp operation.
2Reliability
If rendering is performed for both left and right eyes in virtual reality, then a fully immersive experience is achieved, but the load on the graphics processor is doubled
Solution Approach 1:
The patent applies segmentation by dividing the rendering process into distinct stages: first generating a single intermediate image with optimized non-uniform pixel distribution, then applying warp operations to create the final left and right eye images. This segmentation allows the computationally intensive rasterization to be performed once rather than twice, significantly reducing the graphics processor load while still producing the required stereoscopic pair for immersive virtual reality experience.
Data Source
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AI summary
An apparatus and method are described for a non-uniform rasterizer. For example, one embodiment of an apparatus comprises: a graphics processor to process graphics data and render images using the graphics data; and a non-uniform rasterizer within the graphics processor to determine different resolutions to be used for different regions of an image, the non-uniform rasterizer to receive a plurality of polygons to be rasterized and to responsively rasterize the polygons in accordance with the different resolutions.