Piecewise Linear Rasterization for VR Display Distortion Compensation
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Solution Overview
Problem
Current wide-screen rendering techniques, such as those used in VR goggles, suffer from optical distortion and inefficient resource utilization due to non-linear distortion lenses, leading to reduced resolution and performance issues.
Innovation Solution
The method involves dividing the screen space into regions with varying horizontal and vertical sampling factors and offsets to render geometry objects, allowing for adaptive pixel rendering that counteracts distortion and optimizes resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If non-linear distortion lenses are used to project content onto the periphery of the view, then the viewer can see 3D content in the periphery, but objects appear distorted with curved edges
Solution Approach 1:
The patent applies preliminary anti-action by intentionally inducing non-linear barrel distortion during the rendering process to counteract the optical pin-cushion distortion caused by the distortion lens. This pre-applied opposite distortion ensures that when the distorted rendered content passes through the lens, the final perceived image appears geometrically accurate to the viewer
Solution Approach 2:
The patent changes the rendering parameters by applying non-linear transformation functions to the geometry and texture coordinates during rasterization. These parameter transformations modify how vertices and pixels are mapped across the display screen, creating barrel distortion that compensates for the lens-induced pin-cushion effect
2Manufacturing precision
If barrel distortion is induced to counteract pin-cushion distortion, then geometric accuracy is improved, but content near the center is magnified and content near edges is compressed, reducing resolution in the center
Solution Approach 1:
The patent applies local quality by using adaptive sampling rates that vary across different regions of the display screen. The sampling rate is dynamically adjusted based on the local magnification/compression factors introduced by barrel distortion, ensuring that each region receives an appropriate number of rendered pixels to maintain consistent perceived resolution across the entire field of view
Solution Approach 2:
The patent implements dynamics by making the sampling rate a dynamic parameter that changes based on the local distortion characteristics at each pixel location. Rather than using a fixed uniform sampling rate, the system dynamically adjusts the sampling density to compensate for the non-uniform spatial transformation caused by barrel distortion
3Ease of manufacture
If uniform sampling rate is used across the entire display screen, then rendering is simple, but more pixels are rendered near the edges than needed, wasting compute resources
Solution Approach 1:
The patent applies local quality by implementing region-specific sampling rates where different portions of the display screen use different sampling densities. The sampling rate is locally optimized based on the distortion characteristics and perceived importance of each region, allowing higher sampling in areas requiring more detail and lower sampling in areas where fewer pixels are needed
Solution Approach 2:
The patent applies partial action by rendering only the necessary number of pixels in each region rather than uniformly oversampling the entire screen. By calculating the optimal sampling rate for each local region based on distortion factors, the system renders exactly the amount of detail needed without unnecessary computational overhead
4Measurement precision
If adaptive sampling rates are used with different regions, then resolution is optimized for each area, but the rendering process becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the display screen into multiple regions, each with its own sampling rate parameters. This segmentation allows the rendering system to apply different levels of detail to different areas of the screen, optimizing resolution where needed while reducing complexity in other areas through systematic regional division
Data Source
AI summary
One embodiment of the present invention includes a method for rendering a geometry object in a computer-generated scene. A screen space associated with a display screen is divided into a set of regions. For each region; a first sampling factor in a horizontal dimension is computed that represents a horizontal sampling factor for pixels located in the region, a second sampling factor in a vertical dimension is computed that represents a vertical sampling factor for the pixels located in the region, a first offset in the horizontal dimension is computed that represents a horizontal position associated with the region, and a second offset in the vertical dimension is computed that represent a vertical position associated with the region. When the geometry object is determined to intersect more than one region, an instance of the geometry object is generated each region that the geometry object intersects.