Errors CHM creating

[Bastian Schumann]

Hi everbody,

I get several Errors while trying to create a CHM. I use the following commands:

set PATH=%PATH%;C:\Users\s219727\Desktop\LAStools\bin;

set NUM_CORES=4

ECHO

mkdir temp_out

for %%F in (height_bodenmais\*.las) do (

rmdir tmp_chm /s /q

mkdir tmp_chm

las2dem -i %%F -drop_z_above 0.1 -step 0.33333 -o tmp_chm/chm_ground.bil

lasthin -i %%F -subcircle 0.1 -step 0.16667 -highest -o tmp_chm/temp.laz

las2dem -i tmp_chm/temp.laz -step 0.33333 -kill 1.0 -o tmp_chm/chm_00.bil

las2dem -i tmp_chm/temp.laz -drop_z_below  2 -step 0.33333 -kill 1.0 -o tmp_chm/chm_02.bil

las2dem -i tmp_chm/temp.laz -drop_z_below  5 -step 0.33333 -kill 1.0 -o tmp_chm/chm_05.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 10 -step 0.33333 -kill 1.0 -o tmp_chm/chm_10.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 15 -step 0.33333 -kill 1.0 -o tmp_chm/chm_15.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 20 -step 0.33333 -kill 1.0 -o tmp_chm/chm_20.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 25 -step 0.33333 -kill 1.0 -o tmp_chm/chm_25.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 30 -step 0.33333 -kill 1.0 -o tmp_chm/chm_30.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 35 -step 0.33333 -kill 1.0 -o tmp_chm/chm_35.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 40 -step 0.33333 -kill 1.0 -o tmp_chm/chm_40.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 45 -step 0.33333 -kill 1.0 -o tmp_chm/chm_45.bil

las2dem -i tmp_chm/temp.laz -drop_z_below 50 -step 0.33333 -kill 1.0 -o tmp_chm/chm_50.bil

lasgrid -i tmp_chm/chm*.bil -merged -step 0.33333 -highest -set_min_max 0 50 -o temp_out/%%~nF.asc

)

The Errors I get are in the attached screenshot.

Cheers,

Basti

[Martin Isenburg]

Hello Bastian,

there are too many points in your "tmp_chm/temp.laz" file. Either your input LAS files have already more than 20 million points or the point count is inflated beyond this limit when you lasthin the points with the -subcircle option that replaces each point with 9 copies (in a circular formation) and then keeps the -highest one per cell. If it is the first you need to use smaller tiles. If it is the latter you could try to use a coarser grid for -step, a smaller radius for  -subcircle, or omit the -subcircle option altogether,

Alternatively you can use blast2dem that has an upper limit of 2 billion in terms of input number of points instead of las2dem that only handles up to 20 million ...

Regards,

Martin @rapidlasso

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[Bastian Schumann]

Hello Martin,

thanks for your help. I tryed blast2dem and it worked. But now there a some other errors (see Error_CHM_2.jpg) occuring. 

Regards,

Basti

[Martin Isenburg]

Hello Bastian,

I assume that your highest partial CHMs such as 

las2dem -i tmp_chm/temp.laz -drop_z_below 50 -step 0.33333 -kill 1.0 -o tmp_chm/chm_50.bil

are empty in the sense that all either points are below 50 meters or all triangles are killed. This causes the "streaming TINs" of the BLAST engine to run out of content and exit with an unhappy ERROR message. I should fix that. But I assume your overall workflow should still produce the desired output (unless the non-content BIL rasters give lasgrid troubles).

Martin

[Bastian Schumann]

Hello Martin,

the produced output is ok. I let you know if some other problems occur.

Basti