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3.1.3
Point Cloud Data Analysis
The analysis of point cloud UDP data consists of three steps.
■ Analyze the vertical angle, horizontal angle, and distance of a data point
Take PandarXT-32's Channel 5 in Block 2 as an example:
1) Vertical angle of Channel 5 is 11°, according to Appendix I (Channel Distribution)
· 0° represents the horizontal direction
· Define upward as positive
· The Channel # from the uppermost counts from 1
NOTE The accurate vertical angle is recorded in this LiDAR's unit's calibration file, see Section 1.3 (Channel Distribution).
2) Horizontal angle = current reference angle of the rotor + horizontal angle firing time offset
· Current reference angle of the rotor: Azimuth field of Block 2
· Horizontal angle offset: 0° for Channel 5, according to Appendix I (Channel Distribution)
· Firing time offset = Laser Firing Time of Channel 5 (see Appendix II) * Spin Rate of the Motor (see Section 4.1 Web Control - Home)
· Define clockwise in the top view as the horizontal angles' positive direction
3) Actual distance in real world millimeters = distance measurement * Distance Unit (4 mm)
Distance measurement is the Distance field of Channel 5 in Block 2
■ Draw the data point in a polar or rectangular coordinate system
■ Obtain the real-time point cloud data by analyzing and drawing every data point in each frame
