In both GeoRSS GML and GeoJSON, some explicit CRS needs to be
specified to use 3-coordinate locations. The simplest one for GeoRSS
seems to be epsg:4979 ( urn:ogc:def:crs:EPSG:4979 ). It would need a
slight modification to support the GeoJSON long-lat encoding.
Otherwise use GeoRSS Simple and the elev property.
e.g.
<georss:elev>346</georss:elev>
<georss:point>42.3234 -173.234134</georss:point>
Well-known text description of 4979 (http://spatialreference.org/ref/epsg/4979/
)
GEOGCS["WGS 84", DATUM["World Geodetic System 1984", SPHEROID["WGS 84",
6378137.0,298.257223563, AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0.0,
AUTHORITY["EPSG","8901"]], UNIT["degree",0.017453292519943295],
AXIS["Geodetic latitude",NORTH], AXIS["Geodetic longitude",EAST],
AXIS["Ellipsoidal height",UP], AUTHORITY["EPSG","4979"]]
Josh
On Aug 28, 2009, at 1:05 PM, Ron Lake wrote:
Sorry my example should have been
<Point id = "P1" CRS = "http://www.blah.bla/standardCRS.xml";>
<coordinates>100 200 150</coordinates>
</Point>
But the argument is the same. Similar encodings can be made in JSON
etc.
R
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Andrew Turner
Sent: August 28, 2009 9:57 AM
To: [email protected]; GeoRSS; geojson
Subject: Re: [georss] [Geojson] simple 3D geocode for AR
Simplest?
Just include a 3rd coordinate in GeoRSS-Simple point or GeoJSON point.
No, this is not explicitly valid. But you see where that discussion
gets us. Long windy roads of elusive semantic talk (arguably necessary
in the lon term, but not simple or useable *now*, which is when people
are building these tools).
If we lose interest without achieving a near term concensus,
developers will just do arbitrary, different solutions. Give them a
simple answer now, even if it makes your strict-validation-only-skin
crawl just a little bit. :)
So I say just do it, and we'll catch up with documenting it as uses
emerge.
Also, KML already supports 3D points.
Andrew
(via mobile)
On Aug 27, 2009, at 4:35 PM, Mike Liebhold <[email protected]> wrote:
A friend wrote me with a request for clarification on a topic we've
discussed many times here, but every time we've approached a
consensus the answer seems elusive.
Many devleopers are starting to create applications for iPhones and
Android phones to view location specific data through the
viewfinder using the -imprecise- capabilities of the built in gps
and compass and applications platforms like Layar.
The question:
What is the -simplest- way to geocode a geoannotation in 3D using
geoRSS/Atom, geojson, KML ....?
(Is there a practical reason why WGS '84 shouldn't be implicit, and
a CRS lookup NOT be required?)
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