lasheight skipped files with ground points

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Möst, Karin (LDBV)

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Jul 15, 2021, 11:56:25 AM7/15/21
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Hi Martin,

using LAStools 20210612 we encountered a problem with lasheight.
Formerly the command-line option '-skip_files skipped files with few ground points or a degenerate triangulation.
LAStools 20210612 seems to skip files with only ground points.

Logging:
all points match classification_mask 4. skipping....

I assume this because several files with ground points only were skipped during our processing.

Thank you
Karin


Martin Isenburg

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Jul 15, 2021, 11:59:46 AM7/15/21
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Hello Karin,

I do not think anything has changed in lasheight recently. The logic that files get skipped when they exclusively contain ground points (hence no normalization can take place since all points are part of the zero ground) has always been there. Maybe you never had files before where every point was part of the ground class. In which way is this causing a problem? Would you like to see a different behaviour?

Regards,

Martin

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Möst, Karin (LDBV)

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Jul 16, 2021, 11:55:18 AM7/16/21
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Hello Martin,

 

in our workflow we use lasheight  to detect low noise. Up to now we skipped files without ground points or with few ground points.

This was also a comfortable way to detect tiles with missing / very few ground points – they were missing in the tiled dataset.

 

Just now we have a lake  (Starnberger See, I think you know it).

We do not classify water so points on a water body are classified as ground.

In the tiled dataset some tiles were missing and we checked, if there are really no points.

We found out, that lasheight  skipped them. The solution could  be  just to change the command-line option. But tiles without ground points will not be notified any more.

 

Maybe files containing exclusively ground points can simply be copied, not skipped?

I do not know if this behavior interferes with workflows of other users, though.

 

Regards

Karin

Martin Isenburg

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Jul 16, 2021, 12:39:56 PM7/16/21
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How about we see this as "a comfortable way to detect tiles with only ground points" that could also be the result of an erroneous workflow. It does not happen often that files *ONLY* contain ground points, so that might be a good check to keep in place.

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