HMD Distortion Meshes for Radial and Chromatic Aberration Correction
Solution Overview
Problem
Head-mounted displays (HMDs) suffer from image distortions, particularly radial and chromatic aberrations, due to the use of wide-angle lenses, which degrade image quality and are not effectively addressed by existing pre-warping methods like pixel shaders, especially in graphics architectures that do not support them.
Innovation Solution
A distortion compensation system that includes an image mapping module, radial aberration compensation (RAC) module, chromatic aberration compensation (CAC) module, and blending module, which map and correct images onto distortion meshes, applying bi-cubic texture interpolation and lens-specific parameters to reduce distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixel shaders are used for pre-warping to correct radial distortions, then radial distortion correction is achieved, but image quality is degraded due to discrete resampling and compatibility issues with graphics architectures
Solution Approach 1:
The patent segments the image correction process into multiple independent distortion meshes (e.g., 4x4 grid), where each mesh handles a specific region. This segmentation allows continuous warping within each mesh while avoiding global discrete resampling, thus maintaining image quality while correcting radial distortions.
Solution Approach 2:
The patent changes the approach from discrete pixel manipulation to continuous coordinate transformation using warping parameters. By defining continuous warping functions for each distortion mesh and using bilinear interpolation, the system maintains image quality while achieving distortion correction without relying on pixel shaders.
2Weight of stationary object
If cheaper, lighter lenses are used in HMDs, then device weight and cost are reduced, but chromatic aberrations and radial distortions increase
Solution Approach 1:
The patent applies preliminary anti-action by pre-warping the image content in the opposite direction of the expected lens distortion. The distortion meshes are configured to counteract the pin-cushion effect of wide-angle lenses, and chromatic aberration correction is pre-applied through separate color channel warping, so that when the lens is applied, the distortions are already compensated.
Solution Approach 2:
The patent introduces distortion meshes as an intermediary between the image source and the lens. These meshes act as a computational layer that pre-corrects distortions before the light passes through the lens, allowing the use of cheaper lenses while maintaining image quality through software-based correction.
3Manufacturing precision
If discrete resampling is used in pixel shaders for image pre-warping, then distortion correction is achieved, but image quality is lost
Solution Approach 1:
The patent replaces the mechanical pixel shader resampling system with a software-based continuous warping system. Instead of using hardware pixel shaders that perform discrete resampling, the patent uses CPU/GPU-based coordinate transformation with bilinear interpolation, which provides continuous warping and avoids the quality loss associated with discrete resampling.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3C
AI summary
Systems and methods may provide a plurality of distortion meshes that compensate for radial and chromatic aberrations created by optical lenses. The plurality of distortion meshes may include different lens specific parameters that allow the distortion meshes to compensate for chromatic aberrations created within received images. The plurality of distortion meshes may correspond to a red color channel, green color channel, or blue color channel to compensate for the chromatic aberrations. The distortion meshes may also include shaped distortions and grids to compensate for radial distortions, such as pin cushion distortions. In one example, the system uses a barrel-shaped distortion and a triangulation grid to compensate for the distortions created when the received image is displayed on a lens.