Foveated Rendering Algorithm for VR Ray Traversal Optimization
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Solution Overview
Problem
Conventional rendering techniques for virtual reality and augmented reality are computationally inefficient due to assumptions based on uniform ray distribution and rectangular displays, failing to provide real-time performance and flexibility for non-pinhole cameras and curved viewing surfaces.
Innovation Solution
A primary visibility algorithm using a bounding volume hierarchy and a two-level frustum culling/entry point search algorithm, combined with multi-sample anti-aliasing, to optimize ray traversal and reduce memory bandwidth, enabling real-time rendering of complex graphics features like lens distortion and wide field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional raycasting with uniform ray distribution is used, then object visibility can be determined, but computational efficiency deteriorates and real-time performance is not achieved
Solution Approach 1:
The patent divides the viewing surface into multiple regions (foveated region and peripheral region) with different ray sampling densities. The foveated region uses higher ray density for detailed viewing, while the peripheral region uses lower ray density, thereby segmenting the computational workload according to human visual perception priorities and achieving real-time performance.
Solution Approach 2:
The patent applies different ray casting strategies to different regions of the viewing surface. In the foveated region, uniform ray distribution is maintained for high quality rendering, while in the peripheral region, reduced ray density is applied. This local differentiation optimizes computational efficiency while maintaining perceived image quality.
2Adaptability or versatility
If conventional rendering techniques are used, then rectangular displays are supported, but flexibility for curved viewing surfaces and non-pinhole cameras is lost
Solution Approach 1:
The patent implements a dynamic rendering system that adapts ray casting parameters based on the specific viewing configuration. The system dynamically adjusts ray density, distribution, and origin points according to whether the display is rectangular or curved, and whether pinhole or non-pinhole camera models are used, thereby achieving versatility without excessive complexity.
3Productivity
If uniform ray distribution is assumed, then rectangular displays with limited field of view are optimized, but performance deteriorates for VR displays with curved viewing surfaces
Solution Approach 1:
The patent changes key rendering parameters including ray density, ray origin distribution, and viewing angle based on the display type. For curved VR displays, it adjusts these parameters to match the curved geometry and wide field of view, thereby maintaining high rendering performance across different display configurations.
Data Source
AI summary
In one embodiment, a computer system may determine an orientation in a 3D space based on sensor data generated by a virtual reality device. The system may generate ray footprints in the 3D space based on the determined orientation. For at least one of the ray footprints, the system may identify a corresponding number of subsamples to generate for that ray footprint and generate one or more coordinates in the ray footprint based on the corresponding number of subsamples. The system may determine visibility of one or more objects defined within the 3D space by projecting a ray from each of the one or more coordinates to test for intersection with the one or more objects. The system may generate an image of the one or more objected based on the determined visibility of the one or more objects.