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

[Van Dyke, Daryl]

LAStools IIRC encodes the non-standard HAG field into the 'user bytes'
portion of the LAS file.  It's special-sauce approach to encoding that
information into a user-expandable portion of the LAS standard.

To keep in mind: the HAG field (again, IIRC) is based on an internal
integer representation - it quantizes the data into the binned integers to
store them.  You want to ensure the resolution of the storage is
appropriate for your application (though for most tree sizes, in most
units, it's probably fine).

I don't think you'll find any tools outside of LASTools that support that
feature.  You may also not be aware that the 'free' or non-licensed version
of LASTools imposes noise on output.

Daryl

On Wed, Nov 9, 2016 at 12:00 PM, <liblas-devel-request at lists.osgeo.org>
wrote:

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> Today's Topics:
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>    1. libLAS and HEIGHT_ABOVE_GROUND attribute (Alexandre Guyot)
>
>
> ---------- Forwarded message ----------
> From: Alexandre Guyot <alexguyot at yahoo.fr>
> To: "liblas-devel at lists.osgeo.org" <liblas-devel at lists.osgeo.org>
> Cc:
> Date: Tue, 8 Nov 2016 21:00:17 +0000
> Subject: [Liblas-devel] libLAS and HEIGHT_ABOVE_GROUND attribute
> Hi,
>
> I'm using the liblas python API to read through some LiDAR point clouds.
> I can access all the standard point attributes of my dataset, however I
> can't figure out how to read the HEIGHT_ABOVE_GROUND value of my points.
> This HEIGHT_ABOVE_GROUND attribute was computed in LAStools using
> "lasheight".
> This attribute is readable on popular LiDAR viewers (GlobalMapper for
> instance) but I don't know how to reach it using libLAS.
>
> Any ideas ?
>
> Thanks a lot,
> Alex
>
>
>
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-- 
_________________________________________
Daryl Van Dyke
GIS Analyst
Klamath Strategic Habitat Conservation Team
US Fish & Wildlife Service - AFWO, R8
(707) 825-5153
https://github.com/GeospatialDaryl
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