Camera Calibration with Regional Refraction Correction
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Solution Overview
Problem
Existing camera calibration methods require dedicated equipment and multiple imaging steps to account for refractive layers, such as windshields, leading to inefficiencies and increased effort, especially when calibrating cameras for wide-angle views.
Innovation Solution
A camera calibration device that calculates deviation amounts between detected and calculated positions of markers in images with and without refractive layers, facilitating calibration by evaluating and correcting these deviations for each region, using a model generation unit, image position calculation, and correction amount calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If camera calibration is performed by imaging the calibration chart with and without the windshield using dedicated equipment, then the calibration accuracy is improved, but the time and effort required for calibration increases significantly
Solution Approach 1:
The patent creates a virtual image of the calibration chart that appears to be positioned behind the windshield, eliminating the need for physical removal of the windshield during calibration. This virtual copying approach maintains calibration accuracy while significantly reducing the time and effort required, as the calibration can be performed with the windshield in place using computational methods rather than physical manipulation.
Solution Approach 2:
The patent introduces an image processing intermediary that generates a virtual calibration chart image accounting for the windshield's refractive effects. This intermediary computation allows the calibration system to work with the windshield in place, avoiding the need for dedicated equipment to physically remove or bypass the windshield, thus reducing calibration time while maintaining accuracy.
2Measurement precision
If dedicated equipment is used to image the calibration chart without the refractive layer, then the calibration precision is improved, but the device complexity and requirement for specialized instruments increases
Solution Approach 1:
Instead of using dedicated equipment to physically remove the windshield, the patent creates a virtual copy of the calibration chart image that accounts for refractive distortion. This computational copying approach eliminates the need for specialized instruments while maintaining calibration precision through software-based correction of the virtual image positions.
Solution Approach 2:
The patent replaces the mechanical approach of physically removing the windshield with dedicated equipment with a computational approach using image processing and virtual image generation. This substitution eliminates the need for specialized mechanical instruments while achieving the same calibration precision through software-based position correction.
3Measurement precision
If the calibration chart is imaged in multiple states (with and without refractive layer), then the deviation measurement accuracy is improved, but the ease of operation decreases due to multiple setup steps
Solution Approach 1:
The patent creates a virtual image of the calibration chart that accounts for the windshield's refractive effects, allowing deviation measurement to be performed with the windshield in place. This eliminates the need for operators to physically remove and reinstall the windshield, significantly improving ease of operation while maintaining deviation measurement accuracy through computational position adjustment.
4Measurement precision
If the refractive layer is removed during calibration, then the image accuracy is improved, but the productivity decreases due to repeated assembly and disassembly
Solution Approach 1:
The patent generates a virtual calibration chart image that compensates for the windshield's refractive distortion, allowing calibration to proceed with the windshield permanently installed. This eliminates the repeated assembly and disassembly cycles, significantly improving calibration efficiency and productivity while maintaining image accuracy through software-based position 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
Facilitates efficient camera calibration by calculating correction amounts for each region, reducing the need for additional equipment and time, and improving accuracy in environments with refractive layers.
Implementation Method 1
an incident angle of a light ray on the refractive layer increases in a wide-angle portion. When an influence of refraction increases, an environment recognition device which recognizes an environment using an image captured by the camera cannot accurately detect a target.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A camera calibration device includes: a deviation amount calculation unit which calculates a deviation amount between a detection position of a calibration object, which is detected for each of regions, with a predetermined size, of an image obtained by a camera imaging the object through a refractive layer, and a calculation position of the object, which is calculated for each of the regions of an image which the camera is capable of capturing without passing through the refractive layer; an evaluation unit which evaluates the deviation amount for each of the regions; and a correction amount calculation unit which calculates, for each of the regions, a correction amount for correcting the detection position of the object to the calculation position of the object, according to an evaluation result of the deviation amount, and calibrates the camera on the basis of the correction amount of the deviation amount calculated for each of the regions.