3D Coordinate Derivation Using Pattern Projection for Low-Reflectance Objects
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Solution Overview
Problem
Existing three-dimensional measurement methods using pattern light projection face challenges with low-reflectance objects, such as black or metal objects, due to weak reflected light, leading to noise-induced errors in determining correspondence between projection and image coordinates, which reduces measurement accuracy.
Innovation Solution
An information processing apparatus that projects patterns with bright and dark portions, uses Gray code or Maximum Min-Stripe-Width patterns, and employs label allocation and edge detection units to derive correspondence relationships and calculate three-dimensional coordinates, correcting noise-induced errors through binarization and spatial encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the exposure time is lengthened to increase observed luminance, then the measurement precision is improved, but the measurement time is extended
Solution Approach 1:
The patent changes the temporal parameter by using multiple sequential pattern projections with different phases (temporal multiplexing) instead of extending exposure time. The system projects patterns at different time points and combines the temporal information to achieve high precision measurement without increasing total measurement time.
2Measurement precision
If the spreading of light is narrowed to increase illumination intensity, then the measurement precision is improved, but the measurement range is narrowed
Solution Approach 1:
The patent transitions from spatial dimension to temporal dimension by projecting multiple patterns sequentially over time. This allows the system to maintain a fixed projection geometry (preserving measurement range) while achieving high precision through temporal separation of pattern information.
3Measurement precision
If a thin striped pattern is used to increase spatial resolution, then the measurement precision is improved, but the contrast is reduced leading to increased noise influence
Solution Approach 1:
The patent ensures continuous and complete observation of pattern information by maintaining the imaging apparatus in a ready state across multiple sequential projections. The system continuously captures pattern information over time without interruption, ensuring that even thin striped patterns are fully observed and their phase information is completely recovered.
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
Enables high-precision three-dimensional coordinate calculation even with low-reflectance objects by reducing noise influence and maintaining pattern constraints, thus improving measurement accuracy without extending measurement time or narrowing the measurement range.
Implementation Method 1
observing light reflected from the measurement target object
Data Source
AI summary
An information processing apparatus includes an image acquisition unit configured to acquire an image obtained by imaging a target object onto which a pattern having a bright portion and a dark portion is projected by a projection unit, an allocation unit configured to allocate, to a pixel in the image, a label corresponding to luminance of the pixel by referring to a characteristic of the pattern, and a correspondence relationship derivation unit configured to derive a correspondence relationship between a position of the pattern in a projection plane of the projection unit and a position of the pattern in the acquired image and a three-dimensional coordinate derivation unit configured to derive three-dimensional coordinates of a surface of the target object based on the derived correspondence relationship.