3D Image Processing Using Multi-Directional Structured Illumination
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Solution Overview
Problem
Three-dimensional image processing apparatuses face challenges in accurately measuring the height of workpieces due to multi-reflection errors, particularly on side surfaces with acute angles, leading to incorrect measurement results that are indistinguishable from normal results, affecting post-processing reliability.
Innovation Solution
The apparatus employs a configuration with a light projecting part that projects structured illumination patterns from an oblique direction, using a digital micro-mirror device to generate first and second projection patterns with different fringe directions, allowing for the comparison of height information between these patterns to detect and correct incorrect height measurements caused by mirror reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structured illumination is projected from an oblique direction to measure height information, then three-dimensional shape measurement is enabled, but multi-reflection errors occur on side surfaces with acute angles causing incorrect measurement results
Solution Approach 1:
The patent introduces a new dimension by projecting illumination patterns in multiple directions (front and side directions) rather than from a single oblique direction. This multi-directional approach allows the system to capture height information from different angles, enabling the detection and correction of multi-reflection errors that occur when measuring side surfaces with acute angles.
Solution Approach 2:
The patent implements a feedback mechanism where the measurement results from multiple illumination directions are compared and synthesized. The system uses the front-direction measurement results to correct errors detected in side-direction measurements, and vice versa, creating a feedback loop that continuously improves measurement reliability by identifying and correcting multi-reflection errors.
2Reliability
If multiple projection patterns with different fringe directions are used to detect incorrect measurements, then measurement reliability is improved, but device complexity and processing time increase
Solution Approach 1:
The patent makes the illumination system multi-functional by enabling it to project patterns in multiple directions (front and side) and with different fringe directions. This universal capability allows a single system to perform both standard height measurement and multi-reflection error detection, eliminating the need for separate dedicated systems while improving reliability.
Solution Approach 2:
The patent employs periodic action by sequentially projecting different projection patterns (first projection pattern with first fringe direction, second projection pattern with second fringe direction) and capturing images at different time points. This time-sequential approach allows the system to gather multiple measurement datasets without requiring all patterns to be projected simultaneously, managing complexity through temporal separation of measurement tasks.
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
This approach enhances the reliability of measurement results by accurately identifying and correcting errors due to mirror reflection, improving the accuracy of height information and reducing measurement errors in three-dimensional image processing.
Implementation Method 1
an angle α between an optical axis of incident light emitted from a light projecting section 110 and an optical axis of reflected light that is incident on a light receiving section 120
Data Source
AI summary
A three-dimensional image processing apparatus includes: a distance image generating part capable of generating a distance image based on a plurality of images captured in an image capturing part; a pattern generating part for generating a first projection pattern and a second projection pattern whose fringe direction is different from that of the first projection pattern as a plurality of projection patterns obtained by changing a fringe direction of a projection pattern; and an incorrect-height determining part for making comparison in height information of a corresponding portion of an inspection target between a first distance image, generated in the distance image generating part based on a first pattern projected image, and a second distance image, generated based on a second pattern projected image, to determine height information of a portion where a difference not smaller than a predetermined value has occurred as incorrect.