Rotated Spherical Viewpoint for VR Panning Distortion
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Solution Overview
Problem
Existing methods for displaying wide field of view (FOV) omnidirectional videos and images suffer from significant geometric distortions, particularly at the corners of the viewport, making them aesthetically unpleasing and unnatural for users, especially when dynamically panning.
Innovation Solution
The method involves generating and providing rotated sphere viewpoints (RSVs) by transforming spherical image data into equirectangular projections, where the area of interest is rotated to minimize geometric distortion, allowing for consistent and minimal distortion across the viewport, even when panning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spherical image data is projected rectilinearly to display on 2D devices, then compatibility with existing image processing techniques is improved, but geometric distortion at viewport corners increases significantly
Solution Approach 1:
The patent transitions from traditional rectilinear 2D projection to equirectangular projection, which preserves the spherical nature of the image data while adapting it for 2D display. This dimensional transformation allows the spherical coordinates to be mapped onto a rectangular grid in a way that minimizes geometric distortion, particularly at the corners of the viewport, while maintaining compatibility with standard 2D display devices and image processing techniques.
2Adaptability or versatility
If larger field of view viewports are used to increase immersion, then user immersion is improved, but geometric distortion and stretching at viewport corners worsens
Solution Approach 1:
The patent implements dynamic viewport extraction from equirectangular projections, allowing the system to adaptively adjust the viewport parameters based on the desired field of view while maintaining consistent distortion characteristics. This dynamic approach enables larger FOV viewports to be rendered with controlled geometric distortion, preserving user immersion without the severe corner stretching that plagues static rectilinear projections.
3Ease of operation
If traditional rectilinear projection is used for dynamic panning, then ease of operation is improved, but object continuity and natural appearance deteriorate due to stretching
Solution Approach 1:
The patent performs preliminary transformation of spherical image data into equirectangular projection before viewport extraction and panning operations. This pre-transformation establishes a coordinate system where subsequent panning operations maintain consistent geometric relationships, preventing the stretching and warping that occurs with rectilinear projections. Objects retain their continuity and natural appearance throughout dynamic panning because the equirectangular basis preserves spatial relationships more faithfully.
Data Source
AI summary
Apparatus and methods for providing a rotated spherical viewpoint (RSV). In one or more embodiments, the RSV is implemented using equirectangular projections (ERPs). The RSV methodologies described herein are particularly suitable for panning within virtual reality (VR) or 360° panoramic content as there is minimal, if any, geometric distortions at the edge of a given viewport. Moreover, the RSV methodologies described herein may reduce the bandwidth requirements of, for example, devices operating in a client-server architecture. Additionally, the computation requirements for providing RSV are minimal and can be provided using relatively simple rotation transforms.