3D Measurement Apparatus Using Segmented Bit Planes for High Resolution
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Solution Overview
Problem
Existing three-dimensional measurement techniques face challenges in measuring small targets with high resolution while maintaining robustness against changes in image capturing conditions, such as ambient light and surface texture, as simply miniaturizing patterns can impair image clarity and distortion occurs on slant surfaces.
Innovation Solution
A three-dimensional measurement apparatus and method that projects a pattern with a two-dimensional structure encoded using unit patterns, where each unit pattern includes a first and second region with an area ratio between 0.3 and 0.9, allowing for high-density data encoding and robust feature point extraction, even under varying image capturing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a higher-density pattern is projected onto a small target to achieve high-resolution three-dimensional measurement, then measurement precision is improved, but the pattern contrast decreases due to ambient light and surface texture, and distortion occurs on slant surfaces, worsening reliability
Solution Approach 1:
The pattern is segmented into multiple bit planes, where each bit plane represents a specific depth range. This segmentation allows the system to measure different depth zones with optimized patterns, improving both resolution and reliability by matching pattern density to specific measurement ranges rather than using a single high-density pattern for all depths.
Solution Approach 2:
The patent changes the parameter of pattern density by using variable bit plane assignments. Different bit planes have different densities, with lower bit planes (deeper ranges) having lower density and higher bit planes (closer ranges) having higher density. This dynamic parameter adjustment optimizes measurement precision for each depth range while maintaining overall system reliability.
2Measurement precision
If the pattern is miniaturized to increase resolution for small targets, then measurement precision is improved, but the robustness against changes in image capturing conditions deteriorates
Solution Approach 1:
The measurement space is segmented into multiple depth ranges, each handled by a specific bit plane with appropriate pattern density. This prevents the need to miniaturize patterns for the entire range, as each segment uses patterns optimized for its specific depth, maintaining robustness while achieving high resolution where needed.
Solution Approach 2:
Different regions of the measurement space (depth ranges) are assigned different pattern densities locally. Closer ranges use higher-density patterns for precision, while farther ranges use lower-density patterns for robustness. This local quality differentiation resolves the contradiction between miniaturization and robustness.
3Measurement precision
If a higher-density pattern is projected to measure small targets at high resolution, then measurement precision is improved, but the pattern may deform due to surface unevenness, worsening manufacturing precision
Solution Approach 1:
The measurement process is segmented into multiple passes, each handling a specific depth range with an appropriate pattern density. This segmentation prevents pattern deformation on slant surfaces by using lower-density patterns for deeper ranges where slant surfaces are more likely to occur, while using higher-density patterns only for closer, flatter surfaces where precision is critical.
Solution Approach 2:
The pattern density parameter is changed based on the depth range being measured. By adjusting pattern density to match the specific measurement range, the system maintains manufacturing precision in pattern projection while achieving high measurement resolution where applicable.
Data Source
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AI summary
Provided are a three-dimensional measurement apparatus, etc. capable of measuring the three-dimensional shape of an object at an improved resolution while increasing robustness of measurements with respect to variations in imaging conditions. This three-dimensional measurement apparatus is provided with: a light projection unit for projecting light of a pattern of coded data onto an object; an imaging unit for capturing an image of the object on which the pattern is projected; and a calculation unit for calculating the position of a three-dimensional point group on the basis of the positions of feature points and decoded data. The pattern includes a plurality of unit patterns that represent at least two bits and that are used to calculate the position of the three-dimensional point group. Each unit pattern comprises a first region and a second region having a larger area than the first region, and the ratio of the area of the first region to the area of the second region is 0.3-0.9.