Multi-Projector 3D Surface Measurement Without Mechanical Rotation
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Solution Overview
Problem
Fringe projection profilometry for 3D surface measurement faces challenges with shadow and obstruction issues due to mechanical movement or rotation requirements, limiting its effectiveness in capturing complete and accurate data without contact.
Innovation Solution
The use of two projectors and two cameras forming four optical 3D sensors positioned around the target surface, calibrated in the same global coordinates, allows for non-contact 3D shape measurement without mechanical shifting or rotation, with a software-controlled system for data processing and phase calculation, including an algorithm for phase invalidity identification to enhance data reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical movement or rotation is used to capture different views of the target surface, then complete surface data can be obtained, but shadow and obstruction issues arise and the measurement process becomes more complex
Solution Approach 1:
The measurement system is segmented into multiple optical sensor pairs (projectors and cameras), with each pair capturing data from a specific viewing angle. This segmentation allows simultaneous multi-view acquisition without mechanical movement, eliminating shadow and obstruction problems while obtaining complete surface data.
Solution Approach 2:
The system transitions from single-view measurement to multi-view measurement by adding spatial dimensionality through multiple optical sensor pairs positioned at different locations. This dimensional expansion enables comprehensive surface capture without requiring mechanical movement in the measurement direction.
2Reliability
If multiple optical sensors are used to capture data from different views, then data density and validity are enhanced, but system complexity increases
Solution Approach 1:
Multiple optical sensors (projectors and cameras) are merged into a coordinated measurement system with unified calibration in global coordinates. The sensors work together as an integrated system, sharing calibration data and coordinate systems, which manages complexity while enhancing data density and validity through multi-view capture.
Solution Approach 2:
The optical sensors are designed with multi-functionality, where projectors can project fringe patterns and cameras capture images. The system uses universal calibration procedures and coordinate systems that apply to all sensor pairs, reducing operational complexity despite having multiple sensors.
3Ease of operation
If calibration is performed in the same global coordinates, then data combination and merging become easier, but calibration complexity increases
Solution Approach 1:
Calibration is performed as a preliminary action before actual measurement, establishing a unified global coordinate system for all optical sensors. This preliminary calibration creates a foundation that simplifies subsequent data combination and merging operations, as all sensors already share the same coordinate reference framework.
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 enables enhanced data density and validity, providing reliable 3D surface reconstruction without shadows or obstructions, improving the accuracy and usability of the measurement process.
Implementation Method 1
Fringe projection profilometry (FPP) is an optical method for measuring a 3D shape or surface of an object... This technique utilizes a projector to project predefined images, which are usually fringe patterns, onto a target surface, and uses a camera to capture the reflected fringe patterns.
Data Source
AI summary
An apparatus for 3D surface measurement of a target surface, the apparatus comprising: a first projector configured to project a fringe pattern onto the target surface; a second projector configured to project a fringe pattern onto the target surface; a first camera configured to capture the fringe patterns projected by the first projector and the second projector; a second camera configured to capture the fringe patterns projected by the first projector and the second projector; and a computer configured to perform fringe pattern processing of the fringe patterns captured by the first camera and the second camera and to perform data stitching and merging to obtain a 3D surface reconstruction.