3D Shape Measurement Using Single Projector Phase Calculation
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Solution Overview
Problem
Conventional three-dimensional shape measurement methods using sinusoidal patterns require a long time due to the need for doubled projection periods when using two types of patterns with different cycles to resolve ambiguity.
Innovation Solution
A three-dimensional shape measuring apparatus and method that uses a single projector to project a short cycle and a long cycle sinusoidal light pattern, allowing for relative and absolute phase calculations to determine three-dimensional coordinates with reduced measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two types of sinusoidal patterns having different cycles are projected to resolve ambiguity, then three-dimensional shape can be uniquely defined, but measurement time is doubled
Solution Approach 1:
The patent combines the functions of multiple projectors into a single projector that sequentially projects both short-cycle and long-cycle sinusoidal patterns. This merging approach maintains the ability to uniquely define three-dimensional shape while reducing system complexity and measurement time compared to using separate projectors for each pattern type.
Solution Approach 2:
The patent employs periodic projection of alternating short-cycle and long-cycle sinusoidal patterns using a single projector. This periodic action allows the system to gather necessary phase information for unique three-dimensional definition while operating within a compressed time frame, effectively resolving the contradiction between measurement precision and time consumption.
2Measurement precision
If multiple projectors are added to uniquely define three-dimensional shape, then ambiguity is resolved, but device complexity increases
Solution Approach 1:
The patent merges the functionality of multiple projectors into a single projector device that can sequentially project both short-cycle and long-cycle sinusoidal patterns. This consolidation maintains the measurement capability to uniquely define three-dimensional shape while significantly reducing device complexity and the number of required components.
Solution Approach 2:
The single projector in the patent serves multiple functions by projecting both short-cycle and long-cycle sinusoidal patterns sequentially. This multi-functionality allows the device to resolve ambiguity and uniquely define three-dimensional shape without requiring separate dedicated projectors for each pattern type, thereby reducing overall system complexity.
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-accuracy three-dimensional shape measurement in a shorter time with a simpler system by reducing the number of projection and capture times, specifically useful for moving objects like faces during authentication.
Implementation Method 1
a single projector device that projects a first light pattern whose luminance changes at a first cycle and a second light pattern whose luminance changes at a second cycle
Data Source
AI summary
A three-dimensional shape measuring apparatus includes: a single projector device that projects a first light pattern whose luminance changes at a first cycle and a second light pattern whose luminance changes at a second cycle that is longer than the first cycle on a measured object; an image capture device that acquire an image of the measured object on which the first or second light pattern is projected; and an image processing device that processes the image acquired by the image capture device. The image processing device includes a relative phase value calculation unit that calculates a relative phase value on each part of the measured object based on a luminance value of an image of the measured object on which the first light pattern is projected, an absolute phase value calculation unit that calculates an absolute phase value on each part of the measured object based on a luminance value and the relative phase value of an image of the measured object on which the second light pattern is projected, and a three-dimensional coordinate calculation unit that calculates three-dimensional coordinates at each part of the measured object based on the absolute phase value.