Wrong file signature?

[Enzo Campomanes]

Hi,

Is it possible for me to correct this LAS file which says has a wrong file signature from my end ? Or do I have to give it back to the source for it to be fixed?

Thanks.

--

Florencio P. Campomanes V

Supervising Science Research Specialist, UP Cebu Phil-LiDAR 2

(+63) 998 964 3916

[Nick Vaughn]

Hi Enzo,

There are tools you can use to edit the file signature yourself.  You can use a hex editor or a scripting language like Python to make the change, which is placing the ascii characters 'LASF' (0x4c 0x41 0x53 0x46) as the first four bytes of the file.  However, if the file signature is blank, then I would expect a lot of the file to have problems, or you do not actually have a las/laz file at all.  

-NIck

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[Martin Isenburg]

Hello Enzo,

make sure the file is not empty (e.g. 0 bytes). The smallest possible LAS file - without any points - should have at least 227 bytes for the LAS header. Whether the content of the file are binary and start with "LASF" you can often simply test with 

D:\LAStools\bin>more ..\data\fusa.laz

as seen in the attached sample. Also lasvalidate will be able to tell if you have a valid LAS/LAZ file or not.

Regards,

Martin