[PROJ] GPS to MSL

[Paul Harwood]

I just pointed to them as an example - primarily because the USNA site does.

I will remove the example from the post as potentially confusing ...

On Wed, 28 Sept 2022 at 11:03, Even Rouault <even.rouault at spatialys.com>
wrote:

> Paul,
>
> Great post.
>
> I've noticed you point to the https://www.agisoft.com/downloads/geoids/
> page which mentions they use the PROJ GTG format. A lot of their files
> have the same names as the ones provided by https://cdn.proj.org/ , but
> they are not exactly the same... Looking at au_ga_AUSGeoid98.tif, it
> appears they have reprocessed them to modify the TIFFTAG_COPYRIGHT
> (removing the license information) and TIFFTAG_IMAGEDESCRIPTION. Also
> adding the nodata value tag (PROJ grids only contain it when they are
> actual grid values at the nodata value). And more annoying they have
> also modified the GDAL_METADATA tag in a way it is not currently
> understood by current GDAL versions (adding the <?xml version="1.0"
> encoding="UTF-8"?> marker before the root <GDALMetadata> element,
> whereas GDAL expects the string to start directly with <GDALMetadata>),
> so the GTG specific metadata is hidden. I'm going to fix the GDAL
> GeoTIFF reader to be more robust to that.
>
> I've also noticed that the dk_sdfe_dvr90.tif file they provide is quite
> different from the PROJ CDN: it has not the same extent and spatial
> resolution.
>
> A bit annoying to reuse the same file names as the ones we provide but
> with different content.
>
> Anyway this is rather for any Agisoft employee reading this email....
>
> Even
>
> Le 28/09/2022 à 10:06, Paul Harwood a écrit :
> > This is not a question but a request.
> >
> > I had to work out an API to convert from GPS coordinates to Height
> > above MSL. Having made it work, I wrote a blog post about the
> > solution, since I like to document things. I have posted it here for
> > three reasons :
> >
> >  1 As a thank you to the team. The simplicity of the actual solution
> > shows just how good PROJ is!
> >
> > 2 In case you want a good laugh, and
> >
> > 3 more seriously, given the impressive competence on this list, I
> > would like to know if I have made any glaring (or even subtle) mistakes.
> >
> > Thank you
> >
> > https://medium.com/p/70b723767787
> >
> > _______________________________________________
> > PROJ mailing list
> > PROJ at lists.osgeo.org
> > https://lists.osgeo.org/mailman/listinfo/proj
>
> --
> http://www.spatialys.com
> My software is free, but my time generally not.
>
>
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