3D Shape Model Projection for Position Orientation Measurement
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Solution Overview
Problem
Existing position and orientation measurement technologies face challenges in accurately associating image features with three-dimensional shape models, particularly in complex environments with varying luminance and inaccurate initial object positions, leading to erroneous associations and decreased precision.
Innovation Solution
A position/orientation measurement apparatus and method that projects three-dimensional shape models onto two-dimensional images, detects image features, and associates them by comparing direction differences, using a model holding means, approximate value acquisition, image acquisition, projection, detection, association, and position/orientation calculation to correct initial object position and orientation estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If edges are associated based on closest vicinity to three-dimensional line segment projections, then association speed is improved, but measurement precision deteriorates due to erroneous associations in complex environments
Solution Approach 1:
The patent introduces luminance information as an intermediary feature to facilitate accurate association between three-dimensional line segments and two-dimensional edges. By incorporating luminance values from the periphery of detected edges and comparing them with expected luminance distributions from the three-dimensional model, the system achieves reliable associations even when multiple edges are present in the vicinity, thus maintaining both speed and precision.
2Measurement precision
If luminance values are used to improve association precision, then measurement precision is improved, but reliability deteriorates due to luminance variations from surface color, light source, and viewpoint
Solution Approach 1:
The patent transforms the luminance comparison approach by changing the parameter being compared from absolute luminance values to luminance distribution patterns and gradients. By analyzing the spatial distribution and changes in luminance rather than fixed values, the system becomes invariant to variations caused by surface color, lighting conditions, and viewing angles, thereby maintaining both precision and reliability.
3Productivity
If approximate position and orientation values are inaccurate, then initial measurement speed is improved, but association accuracy deteriorates leading to erroneous edge-line segment matching
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing luminance distribution characteristics for each line segment in the three-dimensional model before the actual measurement process. This preliminary preparation enables the system to quickly compare detected edges with pre-characterized line segments, maintaining high speed even when approximate position and orientation values are initially inaccurate, while ensuring accurate associations through robust luminance pattern matching.
Data Source
AI summary
A position/orientation measurement apparatus holds a three-dimensional shape model of a object, acquires approximate value indicating a position and an orientation of the object, acquires a two-dimensional image of the object, projects a geometric feature of the three-dimensional shape model on the two-dimensional image based on the approximate value, calculates the direction of the geometric feature of the three-dimensional shape model projected on the two-dimensional image, detects an image feature based on the two-dimensional image, calculates the direction of the image feature, associates the image feature and the geometric feature by comparing the direction of the image feature calculated based on the two-dimensional image and the direction of the geometric feature calculated based on the three-dimensional shape model, and calculates the position and orientation of the object by correcting the approximate value based on the distance between the geometric feature and the image feature associated therewith.