Non-Uniform Ray Casting for VR Chromatic Aberration
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Solution Overview
Problem
Conventional rendering techniques for virtual reality (VR) and augmented reality (AR) are computationally inefficient and lack flexibility due to assumptions based on uniform ray distribution and rectangular displays, which do not hold for non-pinhole cameras and curved viewing surfaces, leading to suboptimal renderings and limited field of view.
Innovation Solution
A rendering system that uses a raycaster with a three-level entry-point search algorithm and distortion meshes to correct chromatic aberration by offsetting color sampling positions and optimizing ray casting, allowing for non-uniform grid sampling patterns and independent color channel sampling, enabling efficient rendering of complex scenes with arbitrary point-to-point ray queries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional rendering techniques use uniform ray distribution through rectangular displays, then computational efficiency is improved, but rendering accuracy and flexibility for non-pinhole cameras and curved viewing surfaces deteriorate
Solution Approach 1:
The patent applies local quality by using non-uniform ray distribution where rays are cast with varying density based on local requirements. Different regions of the curved display surface receive different numbers of rays, with higher density in regions requiring more precision and lower density in regions where fewer rays suffice, thus optimizing computational efficiency while maintaining rendering accuracy for non-pinhole cameras
Solution Approach 2:
The patent implements dynamics by making the ray casting process adaptive and flexible. The rendering system dynamically adjusts ray distribution patterns based on the specific optical properties of non-pinhole cameras and the geometry of curved viewing surfaces, allowing the system to optimize performance for different display configurations and camera models rather than using fixed uniform distribution
2Device complexity
If conventional rendering techniques assume pinhole camera model, then device complexity is reduced, but adaptability to real optical sensors and viewing optics deteriorates
Solution Approach 1:
The patent achieves universality by designing a rendering system that can handle multiple camera models and display geometries through a unified approach. The system uses abstract representations of camera optical properties and display surface geometry, allowing it to work with pinhole cameras, non-pinhole cameras, curved displays, and various viewing optics configurations without requiring separate specialized code paths for each case
Solution Approach 2:
The patent applies parameter changes by representing camera and display properties as configurable parameters rather than fixed assumptions. The rendering system accepts parameters describing optical sensor characteristics, lens distortion, and viewing surface geometry, allowing users to configure the system for different artificial reality devices by simply changing these parameters without modifying the underlying rendering algorithm
3Ease of operation
If uniform ray casting is used for all pixels, then ease of operation is improved, but measurement precision for color sampling deteriorates
Solution Approach 1:
The patent applies local quality by implementing non-uniform ray distribution where the number and density of rays cast for each pixel or region are adjusted based on local requirements. This allows the system to allocate more rays to pixels where high precision color sampling is critical while using fewer rays for pixels where lower precision is acceptable, thus improving overall measurement precision while maintaining ease of operation through automated distribution algorithms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves ray rates exceeding 10 billion rays per second for nontrivial scenes, supporting advanced graphics effects in VR/AR with improved computational efficiency and flexibility, effectively addressing the limitations of existing techniques.
Implementation Method 1
When light from a display in the headset passes through the lens, varying degrees of chromatic aberration may occur for different wavelengths, depending on the properties (e.g., refractive index, thickness, geometry, etc.) of the portion of the lens through which the light passes.
Data Source
AI summary
In one embodiment, a method includes accessing a first distortion definition for a first color component of a collection of pixels and a second distortion definition for a second color component of the collection of pixels; casting, from a viewpoint in a 3D space, a first bundle of rays for the first color component in accordance with the first distortion definition; computing a first set of intersection locations between the cast first bundle of rays and an object in the 3D space; determining, based on the first and second distortion definitions, that a difference between distortions of the first and second color components satisfies a predetermined threshold; estimating, using the first set of intersection locations, a second set of intersection locations on the object for the second color component; and determining color values for the collection of pixels based on the first and second sets of intersection locations.