Shape Measurement Using Frequency-Modulated Illumination Patterns
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Solution Overview
Problem
Phase shifting techniques for shape measurement are flawed due to global illumination and defocus issues, leading to erroneous results in real-world applications.
Innovation Solution
A system that projects a series of illumination patterns with specific frequencies, allowing for the determination of shape measurement by a hardware processor, which accounts for global illumination and defocus effects by selecting frequencies that remain constant across detected images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase shifting techniques are used for shape measurement, then measurement speed and precision are improved, but measurement accuracy deteriorates due to global illumination and defocus effects
Solution Approach 1:
The patent changes the frequency parameter of illumination patterns to resolve the contradiction. By projecting multiple illumination patterns with different frequencies and selecting frequencies that remain constant across detected images, the system achieves accurate shape measurement while accounting for global illumination and defocus effects. This parameter change allows the system to maintain measurement precision while improving reliability by eliminating errors from environmental factors.
2Reliability
If multiple illumination patterns with different frequencies are projected, then measurement accuracy is improved by accounting for global illumination, but the number of required images increases
Solution Approach 1:
The patent extracts only the necessary frequency information from multiple illumination patterns. Instead of requiring complete image sets for all frequencies, the system identifies and uses only those frequency components that remain constant across images, thereby achieving accurate measurement with a reduced number of images while still accounting for global illumination effects.
3Measurement precision
If illumination patterns are projected during separate periods of time, then frequency determination accuracy is improved, but measurement time increases
Solution Approach 1:
The patent applies partial action by projecting multiple illumination patterns at different frequencies during separate time periods, but only processes the subset of frequencies that remain constant across images. This approach achieves accurate frequency determination while minimizing measurement time by avoiding unnecessary processing of all projected patterns.
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
The system effectively measures object shapes by minimizing errors from global illumination and defocus, providing accurate triangulation of points on objects despite these challenges.
Implementation Method 1
phase shifting belongs to a class of active stereo triangulation techniques. In these techniques, correspondence between camera and projector pixels is established by projecting coded intensity patterns on the scene
Data Source
AI summary
Systems, methods, and media for performing shape measurement are provided. In some embodiments, systems for performing shape measurement are provided, the systems comprising: a projector that projects onto a scene a plurality of illumination patterns, wherein each of the illumination patterns has a given frequency, each of the illumination patterns is projected onto the scene during a separate period of time, three different illumination patterns are projected with a first given frequency, and only one or two different illumination patterns are projected with a second given frequency; a camera that detects an image of the scene during each of the plurality of periods of time; and a hardware processor that is configured to: determine the given frequencies of the plurality of illumination patterns; and measure a shape of an object in the scene.