las2las projection + extent

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Ben Riegel

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Apr 22, 2024, 2:09:06 AMApr 22
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Hello,
   I am new at using LAStools. I have a large number of las files that I want to project from a geographic coordinate system - NAD83(NSRS2007) (EPSG 4759) to NAD83 UTM 11N (epsg 26911). I am use las2las64 with the following command:

las2las64 -i {in_las_file} -o {out_las_file} -epsg 26911

The result does not update the extent, which is still in geographic coordinates. How do I specify that header be updated with the new extent?

Thank you for your help!

Sincerely,
Ben Riegel


Jochen Rapidlasso

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Apr 24, 2024, 7:54:09 AMApr 24
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Hi Ben,
this should not happen. If you want you can share a small dataset to be analyzed further.
If you just want to repair the header you can use
    lasinfo64 -repair_bb

Best,

Jochen @rapidlasso

Michael Perdue

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Apr 24, 2024, 4:09:37 PMApr 24
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Hi Ben,

You are using the wrong flag.

"las2las64 -i {in_las_file} -o {out_las_file} -epsg 26911"

Should be:

las2las64 -i {in_las_file} -o {out_las_file} -target_epsg 26911

Note that the flag "-epsg" is a declaration of the input files SRS. It is not a declaration of the target SRS which is what you need to tell las2las if you want your file reprojected. If the SRS contained in the source file is missing or incorrect, you will need to also tell las2las what the input SRS is. For example, If your data is NAD83 original in latlong you would tell las2las something like.

las2las64 -i {in_las_file} -nad83 -latlong -o {out_las_file} -target_epsg 26911

And to be a little nit-picky on the details, it should be noted that EPSG:26911 is specifically a "NAD83 original" coordinate system. So based on what you have written, it suggests that you wish to reproject your points to UTM 11 AND perform a datum transformation from NAD83(NSRS2007) to NAD83original. las2las will not do the datum transformation and my suspicion is that you are looking for EPSG:3718.

So, your command should probably be something like:
las2las64 -i {in_las_file} -latlong -o {out_las_file} -target_epsg 3718

clear as mud?

Mike

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Jochen Rapidlasso

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Apr 24, 2024, 4:12:11 PMApr 24
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Thanks mike, of course - we overlooked the obvious :)

Cheers,

Jochen @rapidlasso
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