<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Dec 22, 2016 at 1:50 PM, Sebastiaan Couwenberg <span dir="ltr"><<a href="mailto:sebastic@xs4all.nl" target="_blank">sebastic@xs4all.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span class="gmail-">On 12/22/2016 09:40 PM, Richard Greenwood wrote:<br>
> One group of transformations that seems to have been ignored for a number<br>
> of years is applying the HARN hpgn grids in the Proj epsg file. For example<br>
> the Proj epsg entry for epsg:3758 uses +towgs84=0,0,0,0,0,0,0 but I believe<br>
> that is should use +nadgrids=wyhpgn.gsb, or at least that's what I change<br>
> it to, which produces results that match NADCON.<br>
><br>
> Is anyone aware of a reason that nadgrids are not referenced in the epsg<br>
> file? Is it maybe just an oversight, something that nobody ever got around<br>
> to? Or because distributing nadgrids would become burdensome?<br>
<br>
</span>wyhpgn.gsb is not included in proj-datumgrids, so referencing it in the<br>
epsg file in proj doesn't make sense as the definition would be unusable.<br></blockquote><div><br></div><div>Not sure I follow you. It works for me.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">If wyhpgn.gsb is licensed freely enough to be included in<br>
proj-datumgrids, updating the definition to use it is an option.<br>
<br>
I've looked for the authoritative source for wyhpgn.gsb but didn't find<br>
it. Who provides the file and under which license?<br></blockquote><div><br></div><div>I probably should have included this in my original post:</div><div><a href="https://trac.osgeo.org/proj/wiki/HarnGrids">https://trac.osgeo.org/proj/wiki/HarnGrids</a><br></div><div><br></div><div><br></div></div>-- <br><div class="gmail_signature"><div dir="ltr">Richard W. Greenwood, PLS<br><a href="http://www.greenwoodmap.com" target="_blank">www.greenwoodmap.com</a></div></div>
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