Distance Image Correction for Wide-Angle Lens Errors
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Solution Overview
Problem
Current distance image acquisition techniques using wide-angle or fisheye lenses face challenges in correcting distance measurement errors due to optical path length and lens thickness differences, especially as the lens angle becomes wider, leading to inaccuracies in wide-range and high-accuracy distance imaging.
Innovation Solution
A distance image acquisition apparatus that includes a light emitting unit, an imaging unit, an optical system with a lens, a correction information storage unit, and a correction unit, which uses correction information corresponding to lens thickness and optical path length differences to correct distance values in the distance image, allowing for reliable reduction of errors and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-angle lens with short focal length is used to obtain wide-range distance image, then the coverage area is improved, but distance measurement accuracy deteriorates due to optical path length difference and lens thickness difference
Solution Approach 1:
The patent applies parameter changes by introducing correction values that compensate for optical path length differences and lens thickness differences. These correction values are stored in a correction value storage unit and applied during distance image generation to adjust the measured distance values, thereby maintaining measurement accuracy while using wide-angle lenses with short focal lengths for wide coverage.
Solution Approach 2:
The patent replaces mechanical/optical correction methods with a computational correction system. Instead of physically adjusting the lens or optical path, the system uses electronic correction values stored in memory and applies them through processing units to correct distance measurements, substituting mechanical complexity with information-based correction.
2Area of stationary object
If a fisheye lens is used to achieve ultra-wide coverage, then the field of view is improved, but distance measurement error increases due to significant optical path differences
Solution Approach 1:
The patent applies local quality by providing different correction values for different regions of the lens. The correction value storage unit stores specific correction values corresponding to different optical path length differences and lens thickness differences that occur at various positions within the fisheye lens, allowing localized correction of distance measurement errors across the ultra-wide field of view.
3Measurement precision
If lens thickness difference between central and outer peripheral portions is considered for correction, then distance measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for optical path length differences and lens thickness differences in the correction value storage unit before actual distance measurement. This allows the correction to be performed simply by retrieving and applying stored values during operation, avoiding complex real-time calculations and reducing device complexity while maintaining high measurement accuracy.
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
The apparatus effectively reduces distance measurement errors by using correction information specific to lens thickness and optical path length differences, enabling the acquisition of wide-range and high-accuracy distance images even with short focal lengths and varying lens angles.
Implementation Method 1
a distance image generation unit that generates a distance image including a plurality of distance values corresponding to a time of flight of the light from the light emitting unit to the light-receiving surface of the imaging unit
Implementation Method 2
an optical system that includes a lens that guides the light emitted from the light emitting unit and reflected in a distance measurement region to the light-receiving surface of the imaging unit
Data Source
AI summary
Provided are a distance image acquisition apparatus capable of obtaining a wide-range and high-accuracy distance image, and an application thereof. The distance image acquisition apparatus includes a distance image generation unit (42) that generates a distance image including a plurality of distance values corresponding to a time of flight of light from an light emitting unit (12) to a light-receiving surface of an imaging unit (20) on the basis of an imaging result of the imaging unit (20); a storage unit (22) that stores correction information corresponding to a lens thickness difference between a plurality of main light beam paths from a lens (14) to the light-receiving surface of the imaging unit (20); and a correction unit (44) that corrects the distance values in the distance image on the basis of the correction information.