How to calculate accurate lidar coverage / LIDAR_POINT_SIZE value
I want to calculate the accurate coverage of lidar points cloud in las format
First attempt with a script to import one by one each las file :
1. Import lidar file: IMPORT TYPE=LIDAR_LAS…
2. Generation of an elevation grid from the previously imported point cloud in las format: GENERATE_ELEV_GRID…
3. calculation of the bounding surface on the newly created TIN: GENERATE_LAYER_ BOUNDS_TYPE=POLYGON…
4. Generation of a report to obtain the covered area (takes into account the holes, great !): GENERATE_REPORT…
The script works perfectly and I do obtain the expected results but it is very long especially for the TIN generation (step 2) since the input lidar files can contain tens of millions of points and extend over large areas, and the obligation to work with high resolutions to obtain accurate results
So I looked for a faster alternative. This alternative works well in the test phase with the graphical interface but I can't script it:
1. import the las file (full resolution, no decimation beforehand)
I define an all black palette whatever the altitude
2. export in black&white geotiff to speed up the process (black covered areas / white not covered areas): EXPORT_RASTER PALETTE=BW...
3. import of the previously created geotiff
4. Creation of the bounding surface: GENERATE_EQUAL_VAL_AREAS...
5. Generation of a report to obtain the covered area (takes into account the holes, great !): GENERATE_REPORT…
In the graphical interface, I can “play” with the size of the lidar points to simulate the coverage, and I get the desired result (accurate and fast).
However, I don't see how to use the LIDAR_POINT_SIZE option in my script.
I always get an error message "ERROR: Parameter LIDAR_POINT_SIZE value must be in range [16,-1]." What is this range [16,-1] ??
I suppose that for each las file processed, I have to calculate the pixel size / geographic resolution equivalence (my las files are in geographic coordinates) but I don't see how to do it?
Thanks for your support
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