Layered Depth Image Texture Rasterization for Crack-Free VR Rendering
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Solution Overview
Problem
Current image-based rendering techniques for complex 3D scenes in virtual reality struggle with efficient rendering on mobile devices due to geometric complexity and the need for precise texture mapping and alpha channel calculations, leading to potential cracks and holes in rendered images.
Innovation Solution
A method involving Layered Depth Images (LDIs) is used to generate texture maps for partition polygons by projecting surfels into target camera spaces, applying color weights, and calculating alpha coverage using level set functions, ensuring smooth blending and crack-free rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If image-based rendering techniques are used for complex 3D scenes, then rendering efficiency on mobile devices is improved, but rendering quality deteriorates due to cracks and holes in rendered images
Solution Approach 1:
The patent segments the complex 3D scene into multiple partition polygons, each with its own texture map generated from LDI samples. This segmentation allows efficient processing of individual partitions while maintaining overall scene quality, resolving the contradiction between rendering efficiency and quality by dividing the large complex rendering task into smaller manageable parts.
Solution Approach 2:
The patent performs preliminary actions by pre-calculating and storing LDI samples, depth values, and color information before rendering. Texture maps are generated in advance from these pre-computed LDI data, and alpha coverage is calculated beforehand using level set functions. This preliminary preparation enables efficient real-time rendering without quality loss.
2Reliability
If precise texture mapping is performed to avoid cracks and holes, then rendering quality is improved, but computational complexity increases
Solution Approach 1:
The patent creates simplified copies of the complex 3D scene in the form of partition polygons with associated texture maps. Instead of directly rendering the full geometric complexity, the system uses 2D texture map copies that capture the essential visual information. This copying approach maintains rendering quality while significantly reducing computational complexity for mobile devices.
Solution Approach 2:
The patent transforms the 3D rendering problem into a 2D texture mapping problem by projecting LDI samples onto 2D texture maps for each partition polygon. This dimensionality change from 3D geometric processing to 2D texture processing reduces computational complexity while maintaining visual quality through proper texture coordinate mapping and alpha blending.
3Reliability
If alpha coverage is calculated for smooth blending, then rendering quality is improved, but processing time increases
Solution Approach 1:
The patent calculates alpha coverage in advance using level set functions during the texture map generation phase, before the actual rendering occurs. By pre-computing alpha values for each pixel based on the LDI depth samples and partition geometry, the system avoids time-consuming alpha calculations during real-time rendering, thus improving processing speed while maintaining smooth blending quality.
Data Source
AI summary
In one general aspect, a method can include combining a partition polygon and a generated texture map to form a model of a scene for rendering in three dimensions in a virtual reality space. The generating of the texture map can include projecting a Layered Depth Image sample in a partition polygon to a point in a source camera window space, projecting the point back into the partition polygon as a surface element (surfel), projecting the surfel to a surfel footprint in a target camera window space, projecting from the target camera window space to the partition polygon, sub-pixel samples included in pixels covered by the surfel footprint, projecting the sub-pixel samples from the partition polygon and into the source camera window space, and applying a color weight to each sub-pixel sample based on the location of the sample in the source camera window space.