Occupancy metric - voxel based metric

[Susana Gonzalez]

Hi Martin,

Would be great to compute the occupancy within the voxels on the forest canopy by classifying each voxel as empty/not empty based on the presence or absence of returns within each voxel and aggregating them by a grid.

 :: Occupancy metric on 25m grid (A count of the number of occupied voxels in a vertical ‘column‘ of 25x25m)

 :: Voxels with 3 dimensions of X Y Z (in meters), in this example, is a 3x3x3m voxel

 lascanopy.exe -i %NORMALISE%\*.laz -step 25 -om 3 3 3 -odir %METRICS% -ocsv

Adding switches will create a useful metric, switches to 1) normalise the number of returns per voxel by the total number of returns in all voxels in that vertical ‘column’ of voxels -  if you go for binary fill/empty it would be useful to have  2) a switch to set a threshold for occupied e.g. -threshold 5 – otherwise noise points and other isolated but unimportant features create ‘full’ voxels.

Could you implement this voxel-based metric? 

Thanks a lot!

Take care!

Susana

 

 

Susana Gonzalez - Forest Engineer, LiDAR Science

 

Interpine Group Ltd

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[Martin Isenburg]

Hello Susana,

Sorry for the late reply but I remember reading this message a long while ago and not understanding the exact meaning of your request. Have you found a way in the meantime to mimic these metrics with lascanopy / lasvoxel and lasgrid?

In your example, you are using a step size of 25 meters and a voxel size of 3 by 3 by 3 meters. That seems "incompatible" to me. Either way I would need a much more detailed description of this "occupancy metric" that you envision below in order to actually implement it. Maybe others who are successfully using voxel based metrics could chime in here.

Regards,

Martin