[georss] Intended lat/long order

[rico.hauke at daimler.com]

Hi,

Sorry for all the trouble/confusion I've caused. I actually always thought 
that lat-long is the correct order *until* I came across this post on 
postgis-users which totally confused me:
(First three lines after the quotes.)

http://postgis.refractions.net/pipermail/postgis-users/2007-October/017453.html

I am providing GeoRSS feeds and store them in a PostgreSQL/PostGIS 
database. So now I know for sure, that the order in GeoRSS is lat long, I 
just have to figure out if the PostGIS WKT Reader really expects long lat?

Thanks,
Rico






creed at opengeospatial.org 
11/08/2007 06:39 PM

To
rico.hauke at daimler.com
cc
jlieberman at traversetechnologies.com, rsingh at opengeospatial.org
Subject
Re: [georss] Intended lat/long order







Rico -
 
Your first example.
 
The axis order in a GML encoding is defined by the Coordinate Reference 
System (CRS). The OGC (and just about every vendor and standards 
organization) now uses the EPSG database as the normative reference for 
all CRS parameters. GeoRSS GML defaults to WGS 84 2d as defined in the 
EPSG database. As such, the order is lat-long. 
 
Believe it or not, axis order is one of the most contenscious topics in 
the geospatial and standards communities. However, the OGC, OASIS, IETF, 
ISO, and others when referencing WGS 84 all use lat-long as this is the 
axis order defined by the CRS entry in the EPSG database. Most GIS systems 
have historically not followed this convention. Hence the controversy. 
FYI, the next version of SQL-Server implements OGC's Simple Features SQL - 
and the axis order is lat-long and they are using WKTs. Finally, FYI, KML 
3.0 will follow the correct EPSG convention and switch axis order from 
long-lat to lat-long. This is not common knowledge, so please do not 
spread this item of information around yet. Thanks
 
Hope this helps. I suspect others will weigh in.
 
Regards
 
Carl Reed, PhD
CTO
OGC
----- Original Message ----- 
From: rico.hauke at daimler.com 
To: georss at lists.eogeo.org 
Sent: Thursday, November 08, 2007 6:51 PM
Subject: [georss] Intended lat/long order


Hi list, 

This might sound stupid, but I was wondering what the lat/long order (eg. 
in a point geometry) is intended to be? 

So if I am located at latitude 37.4 and longitude -122.1 which of the 
following points are valid GeoRSS representations? 

1. lat/long order: 
<gml:Point>
       <gml:pos>37.4 -122.1</gml:pos>
</gml:Point> 

2. long/lat order: 
<gml:Point>
       <gml:pos>-122.1 37.4</gml:pos>
</gml:Point> 

The reason I am asking is that I have to pass the position string into a 
WKT StringReader which wants the input to be in x/y (=long/lat) format. 

Thanks, 
Rico 

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