Does -kill Use 3D or 2D Distances?

[Spencer Floyd]

Hi,

I think I know the answer after some testing, but I'd like to know if the -kill parameter (specifically in blast2dem), uses 2D distances or 3D distances.

With geometric ground classification sometimes struggling with steep areas (often getting missed) I was hoping to use a small -kill value to identify these kind of areas that would show as voids in the resulting DEM. Paired with a slope raster and a certain slope threshold, hopefully these areas can be easily found.

Here is an example of the difference between 2D and 3D distances: 

If the -kill parameter isn't currently using 3D distances, is that something that could be added? 

Thanks in advance.

Spencer

[Jochen Rapidlasso]

Hi Spencer,

thank you very much for your suggestion. We have reviewed this situation. Yes, it is a 2D measurement. In las2dem_new, a new development, this can be implemented quite easily. In blast2dem, it is more complicated. Would it be helpful if we implemented this in las2dem_new?

Cheers,

Jochen @rapidlasso

[Spencer Floyd]

Hi Jochen,

Appreciate the reply.

Adding to las2dem_new would be helpful if it's not too much trouble.

Thanks,

Spencer

--
Download LAStools at
https://rapidlasso.de
Manage your settings at
https://groups.google.com/g/lastools/membership
---
You received this message because you are subscribed to the Google Groups "LAStools - efficient tools for LiDAR processing" group.
To unsubscribe from this group and stop receiving emails from it, send an email to lastools+u...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/lastools/bce0c33a-17b7-4883-8e04-f5d0e03dac35n%40googlegroups.com.

[Jochen Rapidlasso]

Hi Spencer,

thanks for your patience.
We implemented now "-kill3d" for las2dem_new64.
You can test this change on this beta version:
     https://downloads.rapidlasso.de/beta/las2dem_new64_260609beta.zip



The image on the right shows additional cells that were removed in steeper areas.
This change will be included in the next version unless we announce otherwise.

Cheers,

Jochen @rapidlasso

[Spencer Floyd]

Hi Jochen,

Thanks for adding this.

I did some tests of my own on the same lake.laz file. I can replicate your results when I use the -false flag, but when I remove that flag in order to get elevation values, I get some strange results.

las2dem_new64 -i lake.laz -keep_class 2 -kill3d 10 -false

las2dem_new64 -i lake.laz -keep_class 2 -kill3d 10

For my purposes, using the -false flag is fine, but wanted to let you know in case someone else wants to use -kill3d without the -false flag.

Thanks,

Spencer