Geometric Feature Extraction for 3D Measurement
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Solution Overview
Problem
Existing methods for recognizing or measuring the position and orientation of objects using parametric shape models are hindered by long processing times due to the need for sequential search of geometric features on curved surfaces, and they fail to accurately account for the observation direction of the image capturing device, leading to inaccuracies in geometric feature extraction.
Innovation Solution
A geometric feature extracting device that generates two-dimensional parameter planes and normal directions for curved surface patches, selects regions based on a predetermined angle condition between normal and observation directions, and calculates geometric features observable from the observation position, allowing for high-speed extraction of features corresponding to the observation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If geometric features on parametric curved surfaces are sequentially searched to calculate correspondences with captured images, then measurement accuracy is improved, but processing time increases significantly
Solution Approach 1:
The patent pre-calculates and stores normal directions for all points on the parametric curved surfaces before actual measurement. This preliminary action eliminates the need for sequential calculation during measurement, significantly reducing processing time while maintaining measurement accuracy through pre-computed geometric feature data
Solution Approach 2:
The patent extracts and stores only the essential geometric feature data (normal directions) in advance, separating the computationally intensive pre-processing stage from the rapid measurement stage. This extraction allows the measurement system to use pre-computed data without recalculating complex parametric surface properties during real-time operation
2Productivity
If geometric features are extracted without considering observation direction, then processing speed is improved, but measurement accuracy deteriorates
Solution Approach 1:
The patent makes the geometric feature extraction dynamic by incorporating observation direction as a variable. The system selects and extracts geometric features based on the specific observation direction from the image capturing device, ensuring that only relevant features are processed. This dynamic approach maintains high processing speed by avoiding unnecessary feature calculations while improving accuracy through observation-direction-aware feature selection
Data Source
AI summary
A geometric feature extracting device comprising: first input means for inputting a three-dimensional shape model of a measurement object; generation means for generating two-dimensional parameter planes corresponding to curved surface patches that configure the three-dimensional shape model; first calculation means for calculating normal directions to points on the curved surface patches; holding means for holding the parameter planes and the normal directions in association with each other; second input means for inputting an observation direction used to observe the measurement object from an observation position; selection means for selecting regions in each of which the normal direction and the observation direction satisfy a predetermined angle condition from the parameter planes; and second calculation means for calculating geometric features on three-dimensional shape model corresponding to regions selected by the selection means as geometric features that configure geometric feature regions on the three-dimensional shape model, which are observable from the observation position.