[pdal] pdal ground options '--max_window_size' and '--approximate'

[FE]

Sorry for the late reply.

I've thoroughly tested everything again. When setting '--max_window_size' smaller than 1.0, then all points in the resulting las-file are class 2 (ground). Indeed, the command runs to completion but the results are as said. Further, with --max_window_size smaller than 1.0 a verbose level like '-v4' does not show any information such as iterations or anything else. When setting --max_window_size="1.0" everything works well.

The command I use is e.g.:
pdal ground -i in.las  -o out.las --classify --cell_size="0.01" --max_window_size="0.33" --slope="0.18" -v4


I've tested this both with my own pdal built on OS X as well as on Windows with the OSGEO4W installer. On both systems I use stable pdal version 1.1.0 and pcl 1.7.2. The behaviour is the same.




Concerning the '--approximate' option pdal ground seems to ignore at least --cell_size and --max_window_size. This means when running the following command with --approximate:

pdal ground -i in.las  -o out.las --classify --cell_size="0.01" --max_window_size="1.0" --slope="0.18" --approximate -v4

then there is only a single iteration with a much too large window size of 3.0. The window size remains the same independent fro the options I set. The result only has very few ground points located in one small corner of the dataset:

Iteration 0 (height threshold = 0.150000, window size = 3.000000, half size = 1)...ground now has 510 points


The same command without '--approximate' correctly uses much smaller window sizes in multiple iterations:

Iteration 0 (height threshold = 0.150000, window size = 0.030000)...ground now has 3537994 points
Iteration 1 (height threshold = 0.150140, window size = 0.050000)...ground now has 3127295 points
Iteration 2 (height threshold = 0.150280, window size = 0.090000)...ground now has 2747546 points
Iteration 3 (height threshold = 0.150560, window size = 0.170000)...ground now has 2409347 points
Iteration 4 (height threshold = 0.151120, window size = 0.330000)...ground now has 2136748 points
Iteration 5 (height threshold = 0.152240, window size = 0.650000)...ground now has 1972242 points
Iteration 6 (height threshold = 0.154480, window size = 1.290000)...ground now has 1829280 points    



Besides, I am a bit confused concerning the correct syntax of the command options. Sometimes the options are written without '=' and quotes, sometimes only with '=' and sometimes with both:

--max_window_size 0.33
--max_window_size=0.33
--max_window_size="0.33"

Which is the correct writing? Or are they all valid?


Thanks a lot for your help!