3D Shape Detection Using Binary Code Pattern Projection
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Solution Overview
Problem
Current three-dimensional-shape detection methods, such as the slit-light projection method and space code method, face challenges in achieving high-speed detection with sub-pixel precision due to the need for multiple images and errors in pattern light boundary detection.
Innovation Solution
A three-dimensional-shape detection apparatus and method that projects alternate light and dark patterns, generates luminance images, and uses code images with threshold processing to detect boundary coordinates with sub-pixel precision, reducing the number of images required and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images with pattern light are taken to achieve sub-pixel precision boundary detection, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent applies preliminary action by projecting pattern lights with different spatial codes (binary codes) before measurement to pre-divide the measurement space into multiple regions. This allows the system to identify which specific regions contain boundaries of interest, enabling selective detailed measurement only in those regions rather than processing all areas uniformly, thus reducing total measurement time while maintaining sub-pixel precision where needed.
Solution Approach 2:
The patent segments the measurement process into multiple stages: first capturing images with coarse pattern lights to identify boundary regions, then focusing detailed sub-pixel precision analysis only on those identified regions. This segmentation allows the system to achieve high precision selectively rather than uniformly across the entire field of view, reducing overall processing time while maintaining accuracy where required.
2Measurement precision
If the number of slits is increased to improve resolution, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent transitions from the traditional slit-light projection method (one-dimensional scanning) to a two-dimensional spatial code approach. Instead of projecting multiple slits sequentially, the system projects pattern lights with binary codes across the entire field simultaneously, encoding spatial information in multiple dimensions. This allows parallel processing of multiple measurement points, dramatically improving measurement speed while maintaining resolution through the code-based identification system.
Solution Approach 2:
The patent merges multiple measurement functions into a single imaging operation. By projecting pattern lights with embedded binary codes that encode both spatial position and boundary information, the system can simultaneously capture multiple measurement points in one image rather than requiring separate measurements for each point, thus combining multiple operations into one and improving productivity.
3Measurement precision
If gray-code pattern light is projected to reduce coding errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses simplified binary code patterns that can be easily generated and projected, replacing the more complex gray-code system. The binary code patterns serve as a functional copy or alternative representation that achieves sufficient measurement precision without requiring the additional complexity of gray-code transitions. This simplifies the projection system while maintaining adequate coding accuracy for the application.
Data Source
AI summary
The present invention relates to three-dimensional shape detection. In the present invention, a plurality of types of pattern lights formed of a series of alternate light and dark patterns are projected onto an object in a time series, an image of the object onto which each pattern light is projected is taken, a plurality of luminance images are generated, a code image having certain codes assigned to the pixels is generated in accordance with a result of threshold processing of the plurality of luminance images with respect to a certain threshold; and the three-dimensional shape of the object is calculated. Further, in the invention, a first pixel that is adjacent to a pixel having a code of interest and that has a code different from the code of interest is detected, in a detection position in a direction crossing the pattern light in the code image, a luminance image having a light-dark boundary in a position corresponding to the first pixel is extracted, from the plurality of luminance images, a pixel area that includes a pixel in a certain area adjacent to the first pixel is determined, an approximate expression that expresses a change in luminance in the extracted luminance image in the pixel area is calculated, a position having a certain luminance threshold in the approximate expression and detecting the boundary coordinates of the code of interest in accordance with the result of calculation is calculated, and the three-dimensional shape of the object is calculated in accordance with the boundary coordinates detected by the boundary coordinate detection unit by using the code image.