[Liblas-devel] Liblas-devel Digest, Vol 79, Issue 1

[Alexandre Guyot]

Hi,
Thanks for your help.Actually, I havent' specified any switch in lasheight.

My file is in LAS 1.2 and effectively has the HAG value as it can be read by some commercial software such as GlobalMapper (as "HEIGHT_ABOVE_GROUND" attribute).
Is it therefore stored somewhere else than in extra-bytes or was LAS 1.2 already using extra-bytes ?
Thanks,Alex
  

      De : Howard Butler <howard at hobu.co>
 À : Martin Isenburg <martin.isenburg at gmail.com> 
Cc : "Van Dyke, Daryl" <daryl_van_dyke at fws.gov>; "Liblas-devel at lists.osgeo.org" <liblas-devel at lists.osgeo.org>
 Envoyé le : Mercredi 9 novembre 2016 21h29
 Objet : Re: [Liblas-devel] Liblas-devel Digest, Vol 79, Issue 1
   

> On Nov 9, 2016, at 2:20 PM, Martin Isenburg <martin.isenburg at gmail.com> wrote:
> 
> Hi,
> 
> I believe that Alex talks about the HAG stored as an additional point atttribute to an "Extra Bytes" field via the '-store_as_extra_bytes' switch.
> 
> http://lastools.org/download/lasheight_README.txt
> 
> There was a discussion on this in the LAStools user forum whether cm resolution with a scale factor of 0.01 and a 16 bits signed integer storage are enough for most trees.
> 
> http://groups.google.com/forum/#!searchin/lastools/lasheight$20store_as_extra_bytes
> 
> "Extra Bytes" fields are described in the LAS 1.4 specification and are therefore also more and more readable in other software.

All of this is accurate information.

Additionally, libLAS does not support LAS 1.4 or support writing LAS 1.4 extra bytes descriptor VLRs. You'll need to use LAStools or PDAL or LASpy to achieve this task if open source is a priority for you.

Howard
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