<div dir="ltr"><div><div><div><div>Hi<br></div>When you chose the UTM projection with +proj=utm you should define the zone with +zone=..., and avoid +lon_0. </div>The correct lon_0 of zone 12 is 111w.<br></div>Regards<br><br></div>José Gonçalves<br></div><div class="gmail_extra"><br><div class="gmail_quote">2016-05-17 23:15 GMT+01:00 Dean Schulze <span dir="ltr"><<a href="mailto:dschulze@wirelessseismic.com" target="_blank">dschulze@wirelessseismic.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
Thanks Andre. Leaving off the lon_0 was the problem.<br>
<br>
________________________________________<br>
From: <a href="mailto:proj-bounces@lists.maptools.org">proj-bounces@lists.maptools.org</a> [<a href="mailto:proj-bounces@lists.maptools.org">proj-bounces@lists.maptools.org</a>] on behalf of Andre Joost [<a href="mailto:andre%2Bjoost@nurfuerspam.de">andre+joost@nurfuerspam.de</a>]<br>
Sent: Tuesday, May 17, 2016 12:09 PM<br>
To: <a href="mailto:proj@lists.maptools.org">proj@lists.maptools.org</a><br>
<div class="HOEnZb"><div class="h5">Subject: Re: [Proj] Using invproj to get back the inputs to proj<br>
<br>
Am 17.05.2016 um 16:54 schrieb Dean Schulze:<br>
> Leaving off the -r on invproj gives me back the correct latitude, but the longitude is even worse:<br>
><br>
> $ proj +proj=utm +lon_0=112w +ellps=clrk66 -r man.page.lat.lon.txt | invproj +proj=utm +ellps=clrk66<br>
> # proj +proj=utm +lon_0=112w +ellps=clrk66 -r man.page.lat.lon.txt<br>
> # Should give<br>
> # 460769.27 5011648.45<br>
> 3d30'W 45d15'33.1"N<br>
> 3d30'W 45d15'33.1"N<br>
> 3d30'W 45d15'33.1"N<br>
><br>
><br>
> ________________________________________<br>
> From: <a href="mailto:proj-bounces@lists.maptools.org">proj-bounces@lists.maptools.org</a> [<a href="mailto:proj-bounces@lists.maptools.org">proj-bounces@lists.maptools.org</a>] on behalf of Thomas Knudsen [<a href="mailto:knudsen.thomas@gmail.com">knudsen.thomas@gmail.com</a>]<br>
> Sent: Monday, May 16, 2016 11:59 PM<br>
> To: PROJ. 4 and general Projections Discussions<br>
> Subject: Re: [Proj] Using invproj to get back the inputs to proj<br>
><br>
> Try to leave out the -r option in invproj: the output of proj, that you feed into invproj is not in reverse order.<br>
><br>
> Also, do not expect identical output, especially not for data points far off the central meridian.<br>
><br>
> /Thomas<br>
><br>
> Den 16. maj 2016 19.26 skrev "Dean Schulze" <<a href="mailto:dschulze@wirelessseismic.com">dschulze@wirelessseismic.com</a><mailto:<a href="mailto:dschulze@wirelessseismic.com">dschulze@wirelessseismic.com</a>>>:<br>
> Following the example in the man page if I do<br>
><br>
> proj +proj=utm +lon_0=112w +ellps=clrk66 -r man.page.lat.lon.txt<br>
><br>
> where the file man.page.lat.lon.txt contains<br>
><br>
> 45d15'33.1" 111.5W<br>
> 45d15.551666667N -111d30<br>
> +45.25919444444 111d30'000w<br>
><br>
> I get the 3 lines of output shown in the man page:<br>
><br>
> 460769.27 5011648.45<br>
> 460769.27 5011648.45<br>
> 460769.27 5011648.45<br>
><br>
> So far, so good. But when I try to use invproj to get back the original inputs the results are not even close to the inputs:<br>
><br>
> proj +proj=utm +lon_0=112w +ellps=clrk66 -r man.page.lat.lon.txt | invproj +proj=utm +lon_0=112w +ellps=clrk66 -r<br>
><br>
> gives<br>
><br>
> 73d25'28.89"W 3d18'2.678"N<br>
> 73d25'28.89"W 3d18'2.678"N<br>
> 73d25'28.89"W 3d18'2.678"N<br>
><br>
> What is invproj giving me? How do I run invproj to get back my original inputs?<br>
><br>
<br>
You have missed the lon_0 in invproj, so it takes it to Greenwich.<br>
<br>
HTH,<br>
André Joost<br>
<br>
<br>
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</div></div></blockquote></div><br></div>