Equirectangular Optical Flow Estimation via Polar Region Transformation
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Solution Overview
Problem
Current optical flow estimation techniques for equirectangular images face challenges in accuracy due to image distortion, particularly near the poles, leading to artifacts and incomplete data in optical flow maps.
Innovation Solution
The method involves projecting polar regions of a stereo pair of equirectangular images to central regions, generating optical flow maps for both original and transformed pairs, and combining these maps to produce a resultant optical flow map that reduces distortions and artifacts, allowing for accurate optical flow estimation across the entire image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical flow estimation is performed directly on equirectangular images, then processing is simpler and faster, but accuracy deteriorates due to image distortion particularly near the poles
Solution Approach 1:
The patent divides the equirectangular image into multiple regions (central region and polar regions) and processes them separately. The central region is processed using standard optical flow methods, while polar regions are transformed and processed separately, then merged. This segmentation resolves the contradiction by allowing simple processing in most areas while handling distortion-prone areas specially.
Solution Approach 2:
The patent introduces an intermediary transformation step that converts polar regions from equirectangular coordinates to a different coordinate system where optical flow can be estimated more accurately. This intermediary transformation mediates between the distorted equirectangular representation and the accurate optical flow estimation, resolving the accuracy-simplicity contradiction.
2Measurement precision
If epipolar constraints are enforced as post processing, then matching accuracy improves for points close to actual matches, but inability to correct points far from actual matches remains
Solution Approach 1:
The patent applies preliminary coordinate transformation to the polar regions before optical flow estimation, rather than applying corrections after matching. This preliminary action prevents distortion from affecting the matching process in the first place, allowing accurate matching even for points that would otherwise be far from their actual matches.
Solution Approach 2:
The patent changes the coordinate parameters for polar regions by transforming them from equirectangular coordinates to a different representation where the distortion is corrected. This parameter change allows the optical flow algorithm to operate on undistorted data, improving both matching accuracy and reliability simultaneously.
3Measurement precision
If high resolution is maintained throughout the equirectangular image, then detail is preserved, but computational resources are overutilized in regions with high distortion
Solution Approach 1:
The patent segments the image into central and polar regions, applying different processing strategies to each. The central region maintains full resolution for detailed optical flow estimation, while polar regions are transformed and processed with adjusted computational intensity. This segmentation allows detail preservation where needed while optimizing computational resource usage.
Solution Approach 2:
The patent applies local quality by treating different regions of the equirectangular image differently based on their distortion characteristics. The central region receives standard high-quality processing, while polar regions receive transformed processing adapted to their specific distortion properties. This local differentiation optimizes both detail quality and computational efficiency.
Data Source
AI summary
Techniques related to optical flow estimation for equirectangular images are discussed. Such techniques include combining an optical flow map generated using an input pair of equirectangular images and an optical flow map generated using a transformed pair of equirectangular images rotated with respect to the input pair to move polar regions in the input pair to central regions in the transformed pair.