Why aren't there LiDAR records in some black and white parts of the scene?
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This is the actual scene:
This is the corresponding LiDAR scene:
The LiDAR data is from xyz file. The questions are:
Why are there no points for the dark squares on the checkerboard as well as the wall behind? Similarly, why are there no points for the floor but points for the "holes"?
Are xyz files preprocessed so that the undesired points are "removed"?
I'm new to LIDAR and point cloud processing so I'm seeking for help here.
Dark areas = low reflectivity. Light areas = high reflectivity. My guess is the dark squares simply has not reflected light back to the transceiver and then you have no xyz data here.
For the floor my guess is that light is deflected away from aperture and not towards aperture, except for the holes. This depends of course of the sensor and the setup. In airborne lidar you may see the same effect when flying over lakes, just a small strip directly below the aircraft reflects light back to the sensor, else it is deflected (never reaches sensor and no xyz's).
XYZ files may or may not be pre-processed, directly from sensor they are not but some post-processing may take place before You have got your hands in the data.