Distance Calculation Apparatus with Confidence Evaluation
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Solution Overview
Problem
Existing distance measurement techniques face challenges in accurately calculating distance information due to low contrast in images, leading to increased calculation errors and noise resistance issues, particularly when contrast changes occur in specific directions or with high noise levels.
Innovation Solution
A distance calculation apparatus that calculates distance information by comparing local regions of images generated from different pupil regions, with a confidence calculation unit estimating contrast change amounts and noise levels to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If template matching is used to calculate image shift amount, then distance measurement can be performed at high speed without moving lenses, but calculation errors increase when image contrast is low
Solution Approach 1:
The patent changes the parameter used for similarity evaluation from traditional correlation methods to a method based on contrast change amounts and slope calculations. By evaluating the rate of change of contrast in the image regions, the system can accurately determine corresponding points even when overall image contrast is low, thereby improving measurement precision while maintaining high-speed operation.
2Measurement precision
If confidence calculation is performed multiple times to improve accuracy, then distance measurement precision improves, but calculation time increases
Solution Approach 1:
The patent performs preliminary calculations of contrast change amounts and slopes during the image processing stage, so that when confidence calculation is needed, these values are already available. This preliminary action eliminates the need for repeated full calculations, allowing the system to achieve high precision through multiple confidence evaluations without proportionally increasing calculation time.
3Device complexity
If contrast change amount is calculated without considering pupil dividing direction, then calculation is simplified, but confidence calculation becomes incorrect when contrast changes in specific directions
Solution Approach 1:
The patent applies different evaluation criteria to different regions of the image based on their spatial relationship with the pupil dividing direction. By considering the local orientation and contrast characteristics in relation to the pupil dividing direction, the system accurately evaluates confidence for each region without requiring complex global calculations, thus maintaining simplicity while improving precision.
Data Source
AI summary
A distance calculation apparatus calculates distance information based on a first image, which is generated based on luminous flux that passed through a first pupil region, and a second image, which is generated based on luminous flux that passed through a second pupil region. The distance calculation apparatus includes a distance calculation unit to calculate the distance information by comparing a local region of the first image and a local region of the second image and a confidence calculation unit to calculate confidence of the distance information based on a contrast evaluation value, which is a value indicating a magnitude of a contrast change amount in the local region of the first image, in the local region of the second image, or in a local region of a composite image of the first image and the second image.