How ToF Cameras Perform Lens Calibration

How does the ToF camera perform lens calibration? Why do you need to perform lens calibration? When the ToF camera is aimed at the center of the object, theoretically the center of the object will be imaged at the center of the camera; however, due to errors in the assembly of the ToF camera, the actual image is not at the center of the camera, but will have a certain offset, we Defined as optical center shift; in addition, when the camera getting objects photo, there will be more or less certain deformation, which we often call pincushion distortion.
Purpose of ToF lens calibration is to solve the problems of optical center offset and distortion caused by the inevitable tolerances in the manufacturing and assembly process. Thus, a relatively ideal optical image is obtained, which lays the foundation for the subsequent development of other calibrations. The calibrated parameters are also used when the depth information is loaded into a point cloud, which has a great impact on the generation quality of the point cloud.
The standard for measuring the calibration quality of the lens is the pixel error, that is, the standard deviation between the coordinate transformation according to the calibration parameters and the actual coordinate. After the calibration is completed in the software, this indicator Pixel error will be obtained. The smaller the value is, the more accurate the calibration effect is, as shown in the following figure:

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