crash in lasground

[Andrew Kirmse]

I observed a failure in lasground while processing the following file:

https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/CO_Southwest_NRCS_2018_D18/CO_Southwest_NRCS_B2_2018/LAZ/USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz

Below is the command line.  I had over 5GB of memory free, so I don't think it ran out of memory.

\lastools\bin\lasground -step 1 -i USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz -o eight.laz -vv

Please note that LAStools is not "free" (see http://lastools.org/LICENSE.txt)
contact 'in...@rapidlasso.de' to clarify licensing terms if needed.
processing file 'USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz'.
horizontal units are meter and vertical units are meter. custom mode.
reading 20458956 points. step: 1 m, sub: 3, bulge: 0.2 m, spike: 1+10 m, offset: 0.05 m, stddev: 10 cm ...
took 16.701 sec. finding initial ground points ...
took 27.712 sec. generating initial ground estimate ...
inserted 5210297 deleted 15650. initial ground TIN has 5194647 points.
took 11.645 sec. refining ground ...
inserted 1536753 deleted 69688. refined ground TIN has 6661712 points.
inserted 29178 deleted 1582. refined ground TIN has 6689308 points.
inserted 3431 deleted 309. refined ground TIN has 6692430 points.
inserted 643 deleted 91. refined ground TIN has 6692982 points.
inserted 159 deleted 24. refined ground TIN has 6693117 points.
inserted 71 deleted 17. refined ground TIN has 6693171 points.
inserted 28 deleted 9. refined ground TIN has 6693190 points.
inserted 21 deleted 4. refined ground TIN has 6693207 points.
inserted 7 deleted 5. refined ground TIN has 6693209 points.
inserted 2 deleted 0. refined ground TIN has 6693211 points.
took 72.115 sec. adding terrain features ...
inserted 7069630 deleted 38416. ground TIN with features has 13724425 points.
took 31.148 sec. integrating points 0.05 above ground ...
ERROR processing file 'USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz'. maybe out of memory?

\lastools\bin\lasground -version
Please note that LAStools is not "free" (see http://lastools.org/LICENSE.txt)
contact 'in...@rapidlasso.de' to clarify licensing terms if needed.
LAStools (by in...@rapidlasso.de) version 240605 (unlicensed)

[Jochen Rapidlasso]

Hi Andrew,

first: lasground is only free for up to 3 mio points. please check your license.

2nd: please always use the new 64bit executeables of LAStools.
3nd: think about cleaning/denoising of your data prior processing.

To check your issue we test at a small part of your data:

las2las64 -i USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz -keep_xy -1008991 1687863 -1008800 1688056 -o tmp.laz -set_classification 0

Then we do a 64 bit lasground64 and lasground_new64:

lasground64 -step 1 -i tmp.laz -o tmp2.laz
lasground_new64 -step 1 -i tmp.laz -o tmp3.laz

Both went fast. Looking at the results we see, there is a lot of noise above and below your ground.

Removing the noise is recommended for performance and quality reason.

Anyway, processing the whole file works with the 64 bit version of LAStools without problems:

Log level [VERY_VERBOSE]
LAStools lasground (by in...@rapidlasso.de) version 240605

processing file 'USGS_LPC_CO_Southwest_NRCS_2018_D18_w1009n1687.laz'.
horizontal units are meter and vertical units are meter. custom mode.
reading 20458956 points. step: 1 m, sub: 3, bulge: 0.2 m, spike: 1+10 m, offset: 0.05 m, stddev: 10 cm ...

took 9.926 sec. finding initial ground points ...
took 17.489 sec. generating initial ground estimate ...
took 8.158 sec. refining ground ...
took 62.971 sec. adding terrain features ...
took 22.199 sec. integrating points 0.05 above ground ...
took 101.143 sec. outputting ...
took 10.749 sec. 17148683 points classified as ground.
done. total time 232.642 sec.

Best,

Jochen @rapidlasso