[Liblas-devel] Vertical Datum Conversion (Follow Up: Works fine with new liblas release)

[Howard Butler]

Ibrahim,

It is possible that things are only accurate to two decimals because the
scale of your input header is only 0.01.  I have been working on some
example documentation that explains how to set the scale as part of the
reprojection in more detail.

<http://liblas.org/start.html#reprojecting-an-las-file>

Howard

On Tue, Nov 9, 2010 at 7:50 AM, Ibraheem Ali <ialhakeem at gmail.com> wrote:

> Dear All,
>
> I have downloaded the new release of "libLAS (libLAS 1.6.0b2)" from
> "OSGeo4W" and run the vertical datum conversion command as follow:
>
> las2las gal_000052.las --a_srs EPSG:32615 --t_srs EPSG:32615+5703
>
> which basically assign (wgs84, UTM15) coordinate system to the original
> file ( --a_srs EPSG:32615 ), then transform the vertical datum to NAVD 88 (
> --t_srs EPSG:32615+5703).
>
> It worked great, thanks for the great effort.
>
> I have also compared the result with the results from V-datum and they
> match to the second decimal place very nicely.(sample calcs. included in
> this e-mail).
>
> Thank you very much,
>
> With best regards,
> Ibraheem
>
>
>
> Below some sample lines from the original file, and the results from
> liblas, and V-datum
>
> Original file (WGS 84 UTM15, ellipsoidal height):
>
> 293999.95 3219406.51 -25.55
> 293999.9 3219406.56 -25.53
> 293999.77 3219406.67 -25.53
> 293999.72 3219406.71 -25.53
> 293999.71 3219406.72 -25.51
>
> Liblas Conversion Result  (WGS 84 UTM15, NAVD 88)::
>
> 293999.95 3219406.51 0.94
> 293999.9 3219406.56 0.96
> 293999.77 3219406.67 0.96
> 293999.72 3219406.71 0.96
> 293999.71 3219406.72 0.98
>
> V-Datum Conversion Result (WGS 84 UTM15, NAVD 88):
>
> 293999.95 3219406.51 0.9364
> 293999.9 3219406.56 0.9564
> 293999.77 3219406.67 0.9564
> 293999.72 3219406.71 0.9564
> 293999.71 3219406.72 0.9764
>
>
>
> _______________________________________________
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> Liblas-devel at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/liblas-devel
>
>
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