Stereo Camera Entrance Pupil Correction
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Solution Overview
Problem
In wide-angle cameras, the movement of the entrance pupil center with varying principal ray angles of incidence leads to significant errors in distance calculation, as existing methods do not accurately account for this movement, resulting in deviations from the pinhole camera model and increased errors at distant objects.
Innovation Solution
A stereo camera system that includes a geometric correction unit storing and applying correction information based on the difference between the actual and assumed entrance pupil center positions, and a parallax calculation unit that corrects parallax errors by considering the movement of the entrance pupil center, allowing for accurate geometric correction and distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pinhole camera model is used for distance calculation in wide-angle cameras, then the calculation process is simple, but distance errors increase due to entrance pupil center movement
Solution Approach 1:
The patent changes the parameters of the camera model from the ideal pinhole camera model to a model that accounts for entrance pupil center movement. This involves modifying the optical model to include variable entrance pupil position based on angle of incidence, thereby improving measurement precision while maintaining reasonable computational complexity through pre-calculated correction values.
2Device complexity
If geometric correction is applied at a fixed position, then correction is simple, but distance errors increase at distant objects
Solution Approach 1:
The patent applies dynamic geometric correction by adjusting correction values based on the angle of incidence. Instead of using fixed correction parameters, the system dynamically selects or calculates correction values according to the actual angle of the principal ray, thereby improving accuracy at distant objects while keeping the correction process manageable through pre-computed correction tables.
3Device complexity
If the entrance pupil center movement is not considered, then the pinhole camera model remains valid, but parallax errors occur at distant objects
Solution Approach 1:
The patent introduces correction values as an intermediary element between the simple pinhole camera model and the actual optical system with moving entrance pupil center. These correction values act as a mediator that compensates for the model's inadequacy without requiring complete abandonment of the simplified model, thus maintaining computational efficiency while improving parallax measurement accuracy.
Data Source
AI summary
Provided is a stereo camera that is capable of reducing the distance error created by entrance pupil center movement between different principal ray angles of incidence. In the present invention, imaging system unit 100a images a standard image of an object. Imaging system unit 100b images a reference image of the object. A geometric correction information storage unit 114 stores geometric correction information for the standard image and reference image, which each have error depending on the differences between the positions of the object in the standard image and reference image if the entrance pupil center indicating the point of intersection between the principal ray and optical axis moves according to the angle of incidence and the positions of the object in the standard image and reference image if it is assumed that the entrance pupil center does not move according to the angle of incidence. The geometric correction unit 119 geometrically corrects the standard image and reference image using the geometric correction information.