Distortion-Corrected Rasterization for AR/VR Displays

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Solution Overview

Problem

Traditional Graphics Processing Unit (GPU) methods for rasterization in augmented and virtual reality systems assume constant inter-pixel spacing, leading to inefficiencies and quality degradation when correcting for distortions like lens distortion and panel misalignment, especially in resource-constrained devices.

Innovation Solution

A computing device uses a distortion map to render an inverse-distorted image directly to an AR/VR display by projecting a triangle primitive onto a two-dimensional grid, performing recursive coarse and fine visibility tests, and determining pixel coverage to minimize distortion correction costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional GPU rasterization methods are used with constant inter-pixel spacing assumption, then rendering efficiency is maintained, but image quality degrades when distortion correction is needed

Engineering Contradiction:

Improveimage qualityVSAvoidrendering efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The distortion map is pre-computed and stored, capturing the distortion characteristics of the display system. During rendering, this pre-computed map is used to directly adjust pixel spacing without requiring post-processing, thus maintaining both image quality and rendering efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the inter-pixel spacing parameter dynamically based on the distortion map. Instead of assuming constant spacing, the system varies the spacing parameters according to the pre-computed distortion characteristics, enabling accurate distortion correction while maintaining rendering performance

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If post-processing is used to correct distortion, then image quality is improved, but power consumption increases

Engineering Contradiction:

Improvedistortion correction qualityVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

Distortion correction parameters are pre-computed and integrated into the rendering pipeline before final image generation. This eliminates the need for separate post-processing steps, reducing power consumption while maintaining correction quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The distortion correction functionality is merged with the standard rasterization pipeline. The distortion map is applied during the same rendering pass where geometry is processed, combining two operations into one and eliminating redundant processing that would consume additional power

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If post-processing is used for distortion correction, then image quality is maintained, but rendering time increases

Engineering Contradiction:

Improveimage qualityVSAvoidrendering time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The distortion map is pre-computed and stored for reuse across multiple rendering operations. This eliminates the need to recalculate distortion parameters during each rendering pass, maintaining image quality while significantly reducing rendering time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The distortion correction is segmented into discrete lookup operations based on the pre-computed distortion map. Instead of applying complex distortion calculations during rendering, the system uses simple table lookups and interpolations, maintaining quality while minimizing time overhead

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If traditional rasterization with constant inter-pixel spacing is used, then hardware implementation efficiency is maintained, but adaptability to distorted displays is reduced

Engineering Contradiction:

Improvedistortion correction capabilityVSAvoidhardware implementation complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The distortion map serves as an intermediary data structure that bridges the simple constant-spacing rasterization hardware and the complex distorted display requirements. The map encodes distortion information in a format that can be efficiently queried during rendering, providing adaptability without increasing hardware complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the spacing parameters using pre-computed values from the distortion map rather than implementing complex real-time distortion calculations. This approach provides full adaptability to different distortion types while maintaining simple hardware implementation based on standard rasterization logic

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11423520B2Distortion-corrected rasterization

Publication Date: 2022.08.23 META PLATFORMS TECHNOLOGIES LLC

AI summary

In one embodiment, a method includes projecting a triangle primitive of an object defined in three-dimensional space onto a two-dimensional space, accessing a distortion map generated based on distortion characteristics of a display system, distorting a grid representation of a screen of the display system using the distortion map, determining a visibility of the triangle primitive relative to pixels of the screen by comparing the projected triangle primitive and the distorted grid representation of the screen, rendering an image based on the determined visibility of the triangle primitive, the rendered image being configured to be displayed by the screen of the display system having the distortion characteristics.