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I agree that scope of GEOJSON per se should not be expanded. If a JSON encoding for crs is required, it should be in a separate spec.<br>
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Yes I will add an issue (maybe two) around crs in github... when we get back from school holiday trip to North Queensland!
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Caveat lector - Sent from a tablet using TouchDown<strong>
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<font face="Tahoma" size="2"><b>From:</b> Sean Gillies<br>
<b>Sent:</b> Thursday, 26 June 2014 3:29:14 PM<br>
<b>To:</b> Cox, Simon (CLW, Highett)<br>
<b>Cc:</b> geojson@lists.geojson.org<br>
<b>Subject:</b> Re: [GeoJSON] Removing CRS from GeoJSON<br>
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<div>Links to CRS definitions in GML are already made possible by <a href="http://tools.ietf.org/html/draft-butler-geojson-03#section-3.2">
http://tools.ietf.org/html/draft-butler-geojson-03#section-3.2</a>. That the spec doesn't define a vocabulary for the formats of CRS documents is a bug. I am not in favor of expanding the CRS part of the GeoJSON spec at all, but am in favor of addressing the
existing bug by adding "GML" to the current list of "proj4", "ogcwkt", and "esriwkt".<br>
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Would you be willing to add a new issue to <a href="https://github.com/geojson/draft-geojson/issues">
https://github.com/geojson/draft-geojson/issues</a>, Simon?<br>
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<div class="gmail_quote">On Sat, Jun 21, 2014 at 2:48 AM, <span dir="ltr"><<a href="mailto:Simon.Cox@csiro.au" target="_blank">Simon.Cox@csiro.au</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex; border-left:1px #ccc solid; padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">Looking back in the archives, in the thread with this subject line, I see comments like
<u></u><u></u></span></p>
<pre><span style="font-size:12.0pt; font-family:"Calibri","sans-serif"; color:#1f497d"><u></u> <u></u></span></pre>
<pre><span style="font-size:12.0pt; font-family:"Calibri","sans-serif"; color:#1f497d">>> </span><i><span style="color:black">I don't know of a good web service ... that provides axis order information for arbitrary CRS URN,<u></u><u></u></span></i></pre>
<p class="MsoNormal"><i><span style="font-size:10.0pt; font-family:"Courier New"; color:black"><u></u> <u></u></span></i></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">FWIW - EPSG do provide a service to look up
<i>their</i> CRS here: <a href="http://www.epsg-registry.org/" target="_blank">http://www.epsg-registry.org/</a>
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">The web API is
<a href="http://www.epsg-registry.org/indicio/query?request=GetRepositoryItem&id=urn:ogc:def:crs:EPSG::27700" target="_blank">
http://www.epsg-registry.org/indicio/query?request=GetRepositoryItem&id=urn:ogc:def:crs:EPSG::27700</a> for example. You get GML back, from which the axis order (and everything else) can be deduced, with a little work.
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">Of course the underlying problem with URNs is that you need to know this kind of thing in order to resolve them, and every URN scheme has a different resolver (if at all!). Not very helpful
to most people. That’s why in 2010 OGC changed its approach and prefers http URIs (i.e. URLs) for all new definitions, leveraging DNS instead. And all the old URNs are mapped directly to URLs with this pattern:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">urn:ogc:def:crs:EPSG::27700
</span><span style="font-size:12.0pt; font-family:Wingdings; color:#1f497d">à</span><span style="font-size:12.0pt; color:#1f497d">
<a href="http://www.opengis.net/def/crs/EPSG/0/27700" target="_blank">http://www.opengis.net/def/crs/EPSG/0/27700</a>
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">You still get GML back, but the service is pretty reliable. Somehow the word has not got out – perhaps because URNs are still mentioned in some of the specs which have not been updated since
the policy change. But if you look across the web landscape, URNs are clearly an obsolete technology.
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">The GeoJSON spec (section 3) recommends the OGC URN syntax, as preferable to the old EPSG:27700 syntax. Maybe a minor update to recommend the OGC URL syntax instead (or as well), and then at
least you can have something that usually resolves directly? <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d">Or maybe the IETF process is the opportunity to make such a change? Would it be helpful if I were to submit a formal comment through the IETF lists to do this?
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; color:#1f497d"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span style="color:#00a9ce">Simon J D Cox </span></b><span style="font-size:12.0pt; font-family:"Minion Pro"; color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt; color:black">Research Scientist</span><span style="font-size:12.0pt; font-family:"Minion Pro"; color:black"><u></u><u></u></span></p>
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<a href="mailto:simon.cox@csiro.au" target="_blank">simon.cox@csiro.au</a> </span>
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<p class="MsoNormal"><span style="font-size:10.0pt; color:black">37 Graham Road, Highett, Vic</span><span style="font-size:12.0pt; font-family:"Minion Pro"; color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt; color:black">PO Box 56, Highett, Vic 3190</span><span style="font-size:12.0pt; font-family:"Minion Pro"; color:black"><u></u><u></u></span></p>
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<a href="http://www.csiro.au/SimonCox" target="_blank">www.csiro.au/SimonCox</a> </span>
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-- <br>
Sean Gillies </div>
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