Issue using CDSM in SOLWEIG

[bweeding]

I'm having issues with my CDSM in SOLWEIG. The vegetation doesn't appear properly in the model, and I'm guessing this might be linked to the sky view factors generated. I have included screenshots of the CDSM and sky view factor, and included a zip of the .las and met file used. The driving code can be found here.

For the CDSM to work properly with SOLWEIG, should its values be metres above sea level, or metres above the DEM? Or is there another issue here?

Cheers
Ben

solweig_cdsm_issues.zip

[biglimp]

By the look of it you have an issue that all non-vegetation pixels are not zero. It seems like building pixels are (probably) nodata which will end up as e.g. -9999. IT also seems like you also have included ground elevation which should not in there. A CDSM consist of either vegetation oixels (meter above ground) or non vegetation pixels (zero).

[bweeding]

Ah thank you, I will investigate the generation of the CDSM and attempt to find a solution.

[biglimp]

Maybe you can find some hints from this tutorial. https://umep-docs.readthedocs.io/projects/tutorial/en/latest/Tutorials/LidarProcessing.html#lidarprocessing

[bweeding]

Ah yep I think I have followed that procedure, but there may be a problem with the way my LIDAR data has been classified, I'm checking with the author.

[bweeding]

Just double checking here, following the Lidar processing tutorial it instructs you to construct the CDSM from both vegetation points and ground points:

However you've said above that the CDSM should either contain vegetation points, or zeros. Is this second piece of advice the correct idea?

[biglimp]

Yes, then everything is normalized so that everything will become meters above ground with the optional parameter where you add your ground.dtm.

[bweeding]

Ok great!

When I'm creating the DEM/DSM/CDSM from lidar data (in .las format), do you recommend going from .dtm to .tif, or .asc to .tif?

[biglimp]

I use dtm to tif. Never tested asc to tif

[bweeding]

Ah ok, using fusion as in the tutorial?

…

On Fri, 9 Apr 2021, 17:10 biglimp, ***@***.***> wrote: I use dtm to tif. Never tested asc to tif — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#274 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ANYGKRA4QZEZOKSIWWFQKNTTH2R5FANCNFSM42QCZ4HA> .

[biglimp]

yes