Cylindrical Equal-Area Projection for Panoramic Video Compression
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Solution Overview
Problem
Equirectangular panoramic images or videos require high resolution and bit rates due to uneven area occupation near the poles and equator, leading to data storage, compression, transmission, and rendering challenges.
Innovation Solution
The method involves projecting an equirectangular panoramic image onto a cylindrical surface equal-area projection model, performing coordinate transformation, and using pixel interpolation to generate a panoramic image with reduced resolution and bit rate, ensuring uniform texture area distribution and minimal deformation near the equator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If equirectangular panoramic image is used for storage, then image coverage is complete, but resolution and bit rate increase due to uneven area occupation near poles and equator
Solution Approach 1:
The patent applies different projection characteristics to different regions of the panoramic image. The cylindrical equal-area projection compresses the polar regions where excessive area is occupied, while maintaining equatorial regions with minimal deformation. This local differentiation resolves the contradiction by optimizing data efficiency in high-density regions without sacrificing overall coverage.
Solution Approach 2:
The patent changes the projection parameter from equirectangular to cylindrical equal-area projection. This parameter change transforms the area distribution characteristics, making areas near the poles and equator more uniform. The transformation reduces the total pixel count required while maintaining complete spherical coverage, thus reducing data volume without losing coverage.
2Manufacturing precision
If high resolution is used to maintain image definition, then image quality is preserved, but storage and transmission burden increases
Solution Approach 1:
By changing the projection parameter from equirectangular to cylindrical equal-area projection, the patent achieves more uniform area distribution. This parameter change allows for reduced resolution while maintaining image definition in critical regions, thereby reducing storage burden without sacrificing perceived image quality.
Solution Approach 2:
The patent creates a transformed copy of the panoramic image using cylindrical equal-area projection. This copied representation maintains the essential visual information and image definition while requiring fewer pixels to represent the same scene, thus reducing storage and transmission requirements.
3Quantity of substance
If polar regions are compressed to reduce data, then data efficiency improves, but image deformation increases
Solution Approach 1:
The cylindrical equal-area projection applies targeted compression to polar regions while preserving equatorial regions with minimal deformation. This local quality approach ensures that data efficiency is improved where needed (polar areas) without introducing excessive deformation in regions where it matters most (equatorial areas), thus resolving the contradiction between data efficiency and shape preservation.
Data Source
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AI summary
The present application provides a method and device for constructing a projection image. The method for constructing a projection image comprises: performing projection on an equirectangular panoramic image with a cylindrical surface equal-area projection model to obtain a cylindrical surface equal-area projection image; obtaining a two-dimensional coordinate of each of pixels in the cylindrical surface equal-area projection image; obtaining a two-dimensional coordinate in the equirectangular panoramic image corresponding to each of pixels in the cylindrical surface equal-area projection image; performing pixel interpolation on the cylindrical surface equal-area projection image based on color information of each of pixels in the equirectangular panoramic image and the obtained two-dimensional coordinate in the equirectangular panoramic image corresponding to each of pixels in the cylindrical surface equal-area projection image to generate a panoramic image subjected to the cylindrical surface equal-area projection transformation. The resolution and bit rate of the panoramic image or video can be reduced by the method of the present application.