Windshield Camera Calibration Using Region-Wise Refraction Correction
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Solution Overview
Problem
Existing camera calibration methods require dedicated equipment and time-consuming processes to account for the refractive effects of windshields, leading to inefficiencies and complexity in calibrating cameras for wide-angle views.
Innovation Solution
A camera calibration device that calculates deviation amounts and correction amounts for each region of an image affected by a refractive layer, using a model generation unit to approximate the refractive layer's curved surface and correct image distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If camera calibration is performed by imaging calibration chart through windshield and without windshield separately, then refraction influence can be corrected, but calibration time and effort increase significantly
Solution Approach 1:
The patent creates a virtual image of the calibration chart that appears to be located behind the windshield, allowing calibration to be performed as if the windshield were not present. This virtual copying eliminates the need for physical removal and reinstallation of the windshield while maintaining calibration accuracy.
Solution Approach 2:
The patent introduces a refractive layer model as an intermediary computational element that simulates the optical effects of the windshield. By modeling the refraction mathematically rather than physically removing the windshield, the system achieves accurate calibration without the time-consuming physical setup changes.
2Measurement precision
If dedicated equipment is used to measure parallax and obtain affine transformation information, then calibration accuracy improves, but device complexity and cost increase
Solution Approach 1:
The camera system performs its own calibration using only its existing imaging capabilities. The processor within the camera system calculates the refractive layer parameters and performs the necessary transformations without requiring external dedicated calibration equipment, making the system self-sufficient.
Solution Approach 2:
The patent replaces physical mechanical measurement equipment with computational methods. Instead of using dedicated parallax measurement devices and affine transformation equipment, the system uses image processing algorithms and mathematical models to achieve the same calibration objectives.
3Measurement precision
If windshield is repeatedly mounted and dismounted for calibration, then accurate refraction correction is achieved, but operational complexity and risk of damage increase
Solution Approach 1:
The system performs preliminary computational setup by creating a virtual image position calculation that accounts for refraction effects. This preliminary computational action eliminates the need for repeated physical mounting and dismounting of the windshield during calibration operations.
Solution Approach 2:
By creating a virtual copy of the calibration chart positioned behind the windshield, the system eliminates the need for physical manipulation of the windshield. The virtual image approach allows calibration to proceed without any physical mounting or dismounting operations.
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 and accurate camera calibration by minimizing the impact of refractive layer distortions, enabling reliable object detection in wide-angle views.
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
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.