Calibrating Compound-Eye Distance Measuring Devices With Aberration Correction
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Solution Overview
Problem
Compound-eye distance measuring devices face challenges in achieving high-accuracy calibration due to significant lens aberration, which results in distorted images and reduced feature point detection accuracy, especially in the peripheral regions, leading to sub-pixel calibration difficulties.
Innovation Solution
A calibration method that modifies the luminance distribution affected by lens aberration by calculating the gravity center position of elements in the captured image, using a reference chart with a geometric pattern, and estimating camera parameters with high accuracy, even in the presence of significant lens aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If compound-eye optical systems with multiple single lenses are used to reduce device size, then device size and height are reduced, but lens aberration increases causing image distortion and reduced measurement precision
Solution Approach 1:
The patent applies preliminary action by performing aberration correction before feature point detection. The system pre-calculates aberration correction amounts based on pixel coordinates and luminance values, then applies this correction to the captured image before proceeding with calibration. This preliminary correction compensates for the lens aberration caused by compact optical design, enabling accurate measurement despite the small device size.
Solution Approach 2:
The patent changes parameters by dynamically adjusting aberration correction amounts based on luminance distribution characteristics. The system calculates correction amounts using pixel coordinates and luminance values, then applies variable correction across different regions of the image. This parameter-based correction allows the system to maintain measurement precision while using compact compound-eye optics with inherent aberrations.
2Device complexity
If single lenses are used in compound-eye systems to minimize component count, then device complexity and cost are reduced, but peripheral image quality deteriorates due to sharp lens curves
Solution Approach 1:
The patent extracts the aberration characteristic from the captured image by analyzing luminance distribution patterns. The system identifies and separates the aberration component from the actual object information by comparing captured luminance values with reference data. This extraction allows the system to isolate and correct peripheral image degradation without adding physical components to the optical system.
Solution Approach 2:
The patent introduces an intermediary processing step that mediates between the distorted captured image and the final calibration result. The system uses reference chart data and luminance distribution analysis as an intermediary to calculate correction amounts, which then serve as a bridge to restore peripheral image quality. This intermediary processing enables accurate calibration despite the simplified single-lens optical design.
3Productivity
If feature point detection is performed on images with significant lens aberration, then calibration can be completed, but detection accuracy decreases especially in peripheral regions
Solution Approach 1:
The patent applies feedback by using captured image luminance distribution to determine aberration correction amounts. The system captures a reference chart, analyzes the luminance distribution to identify aberration patterns, calculates correction amounts based on this feedback, and applies the correction iteratively. This feedback loop ensures that feature point detection accuracy is maintained despite the presence of lens aberrations in the captured image.
Data Source
AI summary
A calibration device and method calibrates a distance measuring device which provides captured images with significant lens aberration. The calibration device and method estimate a camera parameter representing a characteristic of each imaging system of a distance measuring device, and perform the following: capture, using the distance measuring device, an image of a reference chart which (i) represents a geometric pattern in which elements are arranged and (ii) is positioned to have a predetermined positional relationship with the distance measuring device; modify a luminance distribution affected by aberration of the lens in the captured image of the reference chart; calculate, as a feature point position, a gravity center position of each element in the captured image whose luminance distribution is modified; and estimate the camera parameter using the feature point position calculated in the calculating and an approximate actual gravity center position in the reference chart.