Large workpiece unable to be fully captured, and its stitched point cloud has misalignment

Q&A
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1

Issue:
The entire image of a large workpiece cannot be captured at one time, and therefore multiple images of different parts of the workpiece should be taken and then the images can be connected together.

But the stitched part of the point cloud is misaligned. How to improve the quality of the stitched point cloud?

There is an obvious misalignment on the connected part, and we cannot find the cause of the problem.

Ambient light and camera model:
The on-site ambient light is poor, and a Laser camera is used.
Camera model: Laser L v3

Why stitching: The Laser camera cannot capture the image of the entire workpiece as the workpiece is large in size, and therefore we captured images of different parts and stitched the point cloud.

Workstation overview

  • The camera is installed on the Z-axis of the truss system, and the camera moves with the truss system.
  • The camera captured 3 images of the large workpiece in the bin, and then the obtained point cloud was stitched together, and an entire edge point cloud was output.
  • The automated truss system was driven by a servo motor, with guaranteed accuracy.
2

Possible reason: error in camera extrinsic parameters

  • Check the workstation and tooling deformation or displacement where the camera is mounted. If so, please fix the workstation, tooling, and mounting part of the camera and then re-calibrate the camera’s extrinsic parameters.
  • Check if the camera has been hit before. If so, check the intrinsic parameters and re-calibrate the extrinsic parameters.
  • Camera calibration for automated truss system: You will need to re-calibrate the camera at three image-capturing points. For details, see User Manual “Complete Calibration for Truss Robot”.

Notes for camera and workstation maintenance:

  • The camera lens should be wiped and cleaned in time.
  • If there is no operation at the workstation for a long time in winter, to prevent the point cloud error caused by temperature drift, please start the camera in advance and capture some images before the camera is put into regular use.