Spherical Image Stitch Zone Calculation for VR Content
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Solution Overview
Problem
Conventional stitching algorithms for spherical images often result in undesirable artifacts around stitch lines due to imperfections in the stitching process, and existing compression techniques are less than optimal for equirectangular projections used in virtual reality content.
Innovation Solution
The development of methods and apparatus for optimal stitch zone calculation in generating projections of spherical images, which involves obtaining multiple images, mapping them onto a spherical collection, and re-orienting them to define an optimal stitch zone characterized by a set of points that minimize distortion in a mean square sense.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stitching algorithms are used to combine multiple images into a spherical projection, then the stitching process can be completed with standard methods, but undesirable artifacts appear around stitch lines due to imperfections in the stitching process
Solution Approach 1:
The patent applies preliminary action by pre-calculating an optimal stitch zone before performing the actual stitching operation. The method determines the optimal stitch zone by analyzing the spherical image data and identifying the region that minimizes distortion and artifacts. This preliminary calculation allows the stitching process to be performed with higher precision by concentrating computational resources on the critical stitch line region, thereby reducing artifacts while maintaining overall stitching accuracy.
2Adaptability or versatility
If equirectangular projections are used for virtual reality content, then the content can be displayed on standard displays, but compression techniques become less than optimal resulting in reduced compression efficiency
Solution Approach 1:
The patent applies local quality by treating different regions of the spherical image with different compression strategies. Instead of applying uniform compression across the entire equirectangular projection, the method identifies regions with varying importance and distortion characteristics. The optimal stitch zone calculation enables the system to apply higher compression to less critical regions while preserving quality in important areas, thereby improving overall compression efficiency without sacrificing display compatibility.
3Manufacturing precision
If the optimal stitch zone is calculated to minimize distortion in a mean square sense, then image quality is improved by reducing artifacts, but the computational complexity of the stitching process increases
Solution Approach 1:
The patent applies segmentation by dividing the stitching process into distinct stages: (1) preliminary optimal stitch zone calculation, (2) focused refinement in the stitch zone region, and (3) standard stitching in non-critical regions. This segmentation allows the computationally intensive distortion minimization to be applied only where necessary (at the stitch lines), while other regions use simpler stitching methods. The result is a balance between image quality improvement and computational complexity management.
Data Source
AI summary
Apparatus and methods for the stitch zone calculation of a generated projection of a spherical image. In one embodiment, a non-transitory computer-readable apparatus comprising a storage apparatus, the storage apparatus comprising instructions configured to, when executed by a processor apparatus, cause a computerized apparatus to identify a stitch line associated with an equatorial area of a plurality of spherical images; re-orient the plurality of spherical images in accordance with the stitch line; and project the re-oriented plurality of spherical images to a selected image projection type.