Non-Uniform Mapping for 360 VR Projection Faces
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Solution Overview
Problem
The high bitrate requirements for representing 360-degree omnidirectional image/video content in virtual reality pose challenges for data compression and encoding, leading to poor image quality and coding efficiency if not properly projected onto projection faces in 360 VR projection layouts.
Innovation Solution
A method and apparatus for processing projection-based frames using non-uniform mapping, where re-sampling is applied to projection faces with different sampling densities to optimize image content distribution, and inverse non-uniform mapping is used for decoding to recover the original projection faces, enhancing encoding efficiency and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform sampling is used for projection faces, then the encoding process is simple, but the image quality and coding efficiency are poor
Solution Approach 1:
The patent applies different sampling densities to different regions of the projection face based on their importance. Important regions (such as those corresponding to the user's field of view or areas with high visual significance) use higher sampling density, while less important regions use lower sampling density. This local differentiation resolves the contradiction by maintaining high image quality where needed while reducing overall complexity and bitrate.
2Manufacturing precision
If high resolution omnidirectional video is used, then the visual quality is high, but the bitrate requirement increases significantly
Solution Approach 1:
The patent changes the sampling density parameter across different regions of the projection face. By varying this parameter spatially, the system maintains high visual quality in important regions while reducing the total number of pixels that need to be encoded, thereby lowering the bitrate requirement for the same perceived quality.
3Manufacturing precision
If non-uniform mapping with different sampling densities is applied, then the coding efficiency and image quality improve, but the processing complexity increases
Solution Approach 1:
The patent divides the projection face into multiple regions with different sampling densities. This segmentation allows the system to apply complex non-uniform mapping only where necessary while using simpler uniform sampling in other areas, thereby managing processing complexity while maintaining image quality improvements.
Data Source
AI summary
A video processing method includes obtaining projection face(s) from an omnidirectional content of a sphere, and obtaining a re-sampled projection face by re-sampling at least a portion of a projection face of the projection face(s) through non-uniform mapping. The omnidirectional content of the sphere is mapped onto the projection face(s) via a 360-degree Virtual Reality (360 VR) projection. The projection face has a first source region and a second source region. The re-sampled projection face has a first re-sampled region and a second re-sampled region. The first re-sampled region is derived from re-sampling the first source region with a first sampling density. The second re-sampled region is derived from re-sampling the second source region with a second sampling density that is different from the first sampling density.