MEMS Projector Calibration for Structured Light 3D Scanning Shift
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Solution Overview
Problem
Structured-light 3D scanners using MEMS scanning mirror projectors face issues with scanning shift, which deforms the projected image and affects the accuracy of generated 3D point cloud data, while being less expensive than DLP projectors, necessitating a method to improve point cloud quality and reduce hardware costs.
Innovation Solution
A projecting apparatus comprising a MEMS mirror projector, an image-capturing device, and a processing device that projects a reversible structured light code, captures image data, decodes it to generate 3D point cloud information, and computes scanning shift information to calibrate the projector, thereby improving point cloud quality and reducing hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a MEMS scanning mirror projector is used, then the hardware cost is reduced, but scanning shift occurs causing deformation of the projected image and affecting the accuracy of the 3D point cloud
Solution Approach 1:
The system performs preliminary calibration by projecting structured light codes and capturing images before actual 3D scanning. The processing device calculates scanning shift information based on the captured images and pre-stored three-dimensional information of the calibration object, obtaining compensation values in advance that are then applied during subsequent scanning operations to correct for MEMS mirror drift.
Solution Approach 2:
The system establishes a feedback loop where the image-capturing device continuously monitors the projected structured light code, the processing device calculates the actual scanning shift based on captured images, and the system applies compensation to correct the drift. This closed-loop feedback mechanism maintains measurement precision while using the lower-cost MEMS projector.
2Ease of manufacture
If a MEMS scanning mirror projector is used, then the hardware cost is reduced, but the projected image is deformed
Solution Approach 1:
The system performs preliminary calibration by projecting structured light codes and capturing images before actual 3D scanning. The processing device calculates scanning shift information based on the captured images and pre-stored three-dimensional information of the calibration object, obtaining compensation values in advance that are then applied during subsequent scanning operations to correct for MEMS mirror drift.
Solution Approach 2:
The system changes the parameters of the projected structured light code dynamically based on calculated scanning shift information. By adjusting the projection parameters using compensation values derived from calibration data, the system corrects for MEMS mirror-induced deformation and maintains accurate geometric relationships in the projected image.
3Ease of operation
If scanning shift is not compensated, then the system operation is simpler, but the quality of the generated point cloud information deteriorates
Solution Approach 1:
The system performs preliminary calibration by projecting structured light codes and capturing images before actual 3D scanning. The processing device calculates scanning shift information based on the captured images and pre-stored three-dimensional information of the calibration object, obtaining compensation values in advance that are then applied during subsequent scanning operations to correct for MEMS mirror drift.
Solution Approach 2:
The system establishes a feedback loop where the image-capturing device continuously monitors the projected structured light code, the processing device calculates the actual scanning shift based on captured images, and the system applies compensation to correct the drift. This closed-loop feedback mechanism maintains measurement precision while using the lower-cost MEMS projector.
Data Source
AI summary
A projecting apparatus includes a projecting device, an image-capturing device and a processing device. The projecting device projects a reversible structured light code onto a surface. The image-capturing device captures the reversible structured light code projected onto the surface and obtains image data. The processing device is coupled to the projecting device and the image-capturing device. The processing device receives the image data, generates three-dimensional point cloud information by performing decoding on the image data, and obtains scanning shift information corresponding to the projecting device according to the three-dimensional point cloud information and three-dimensional information corresponding to the surface.