Parallax Search Window Control for Image-Height Distance Sensing
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Solution Overview
Problem
Existing distance measurement devices using pupil division phase difference methods suffer from variations in baseline length and accuracy due to image height, which are not adequately addressed by existing techniques that adjust search window sizes based on distortion correction.
Innovation Solution
The device sets the search window size based on optical characteristic values, specifically the centroidal gap between luminous fluxes on the exit pupil, to stabilize baseline length and reduce errors in parallax calculation across varying image heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pupil division phase difference method is used to capture images from one optical system, then the device complexity is reduced, but the measurement precision varies with image height due to baseline length variation
Solution Approach 1:
The patent applies dynamics by making the search window size adjustable based on image height. The control unit dynamically changes the search window size according to the specific image height being processed, allowing the system to adapt to varying baseline lengths without changing the physical optical system. This resolves the contradiction by maintaining measurement precision across different image heights while keeping the device structure simple.
Solution Approach 2:
The patent changes the parameter of search window size based on image height to compensate for baseline length variation. By adjusting this computational parameter rather than physical dimensions, the system maintains accurate distance measurements across the entire image field while using a single optical system, thus resolving the contradiction between device simplicity and measurement precision.
2Device complexity
If the search window size is fixed regardless of image height, then the calculation process is simplified, but the parallax calculation accuracy deteriorates at peripheral image heights
Solution Approach 1:
The patent makes the search window size dynamic rather than fixed. The control unit adjusts the search window size according to image height, using smaller windows at peripheral heights where baseline variation is more significant. This dynamic adjustment maintains high parallax calculation accuracy across the image field while adding minimal computational complexity through straightforward conditional logic.
3Manufacturing precision
If distortion correction is applied to maintain image quality, then the image processing capability is improved, but the baseline length variation with image height cannot be compensated, causing measurement accuracy to deteriorate
Solution Approach 1:
The patent segments the image processing into distinct stages: distortion correction is applied first to maintain image quality, then the search window size is adjusted based on image height to compensate for baseline variation. This segmentation allows both image quality improvement and measurement accuracy maintenance to be achieved in sequence without interference.
Solution Approach 2:
The patent introduces an additional parameter adjustment (search window size) that operates independently from distortion correction. By changing the search window parameter based on image height after distortion correction is applied, the system compensates for baseline length variation without affecting the image quality improvements already achieved through distortion correction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces errors in parallax calculation and improves distance measurement accuracy by adapting the search window size to optical characteristics, thereby stabilizing baseline length variations.
Implementation Method 1
Each pixel of an image capturing element is constituted to have divided photoelectric conversion portions while sharing a microlens, and each of the photoelectric conversion portions receives one of luminous fluxes which have passed through different pupil regions in one optical system
Implementation Method 2
calculate an amount of parallax of a set of images having parallax therebetween and captured from different visual points
Implementation Method 3
obtaining an amount of movement of the search window between images with matching patterns within the search window region using a known correlation calculation method
Data Source
AI summary
A distance measurement device includes an image capturing unit configured to be capable of capturing images of first image information and second image information having parallax therebetween from one optical system, and a parallax calculation unit configured to extract image information within a search window from each of the first image information and the second image information and calculate an amount of parallax using a correlation between image information of the first image information within the search window and image information of the second image information within the search window which have been extracted. The parallax calculation unit sets the search window on the basis of an optical characteristic value of an image height for performing parallax calculation. The optical characteristic value corresponds a centroidal gap between a centroid of a first luminous flux forming the first image information and a centroid of a second luminous flux forming the second image information on an exit pupil of the optical system.