Background:
The 3D laser scanner is a non-contact active-sensing system, which has a
number of applications. Many patents have been filed on the technologies for calibrating 3D laser
scanner. A precise calibration method is important for measuring the accuracy of the 3D laser scanner.
The system model contains three categories of parameters to be calibrated which include the
camera intrinsic parameters, distortion coefficients and the light plane parameters. Typically, the
calibration process is completed in two steps. Based on Zhang’s method, the calibration of the camera
intrinsic parameters and distortion coefficients can be performed. Then, 3D feature points on the
light plane should precisely be formed and extracted. Finally, the points are used to calculate the
light plane parameters.
Methods:
In this paper, a rapid calibration method is presented. Without any high precision auxiliary
device, only one coplanar reference target is used. By using a group of captured images of the
coplanar reference target placed in the field of view arbitrarily, calibration can be performed in one
step. Based on the constraint from the planes formed by the target in different directions and the
camera imaging model, a large amount of 3D points on the light plane can easily be obtained. The
light plane equation in the camera coordinates system can be gathered by executing plane fitting to
the 3D points.
Results:
During the experimental process, the developed 3D laser scanner was calibrated by the
proposed method. Then, the measuring accuracy of the system was verified with known distance in
vertical direction of 1mm with sequential shifting motion generated by precision translation stage.
The average value of the measured distances was found to be 1.010mm. The standard deviation was
0.008mm.
Conclusion:
Experimental results prove that the proposed calibration method is simple and reliable.
Comparative Analysis of Polarimetric SAR Calibration Methods
