Talk:Geography Markup Language

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Axis order[edit]

@Jlavezzo - EPSG CRS 4326 uses CS 6422 which clearly states "Ellipsoidal 2D CS. Axes: latitude, longitude. Orientations: north, east. UoM: degree" dr_shorthair (talk) 08:30, 3 June 2011 (UTC)

GDF[edit]

This reference (GDF) does not really belong here. While the other references are actually about GML, this is only a peripheral reference [this comment moved from page content into talk] —The preceding unsigned comment was added by 82.32.5.17 (talkcontribs) 2006-01-23 05:44:58 (UTC)

Mergefrom Cgml and GML Application Schemas[edit]

I'm suggesting that these should be merged into this article as they are currently stubs that seem to only be relavent to this article (they are only linked from here). If these stub articles gain some real content here, they can always be moved back out. – Doug Bell talkcontrib 22:37, 17 March 2006 (UTC)


Not happy about merging Application Schemas page. The topic of application schemas is the always neglected corollary of the GML framework. It usually gets buried in the GML encoding swamp, and that is effectively where you have pushed it again. Yes, the GML Application Schemas page was a stub, but an important statement of intention. Furthermore, in merging, the one link to a publicly available application schema (GeoSciML - https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeoSciML) has been lost! Just because no-one else appears to be willing to tell the world about their community, you shouldn't suppress information previously provided. Not happy at all.

I would be grateful if you would revert this change and re-instate the GML Application Schemas page - my Wikipedia skills are unfortunately not up to this, and I can;t find the page any more. dr_shorthair 03:39, 3 May 2006 (UTC) a

Incosistent usage of the srsDimension attribute[edit]

The srsDimension attribute is used incosistently in the samples. Its first usage is:

 <gml:Point gml:id="p21" srsName="urn:ogc:def:crs:EPSG:6.6:4326">
    <gml:pos dimension="2">45.67 88.56</gml:pos>
 </gml:Point>

where dimension is an attribute of the gml:pos element; and then in the sample for the Point Profile, we see:

 <position>
   <gml:Point srsDimension="2" srsName="urn:ogc:def:crs:EPSG:6.6:4326"> 
     <gml:pos>49.40 -123.26</gml:pos>
   </gml:Point>
 </position>

where srsDimension is an attribute of the gml:Point element. I believe this is the correct one.

Julio —The preceding unsigned comment was added by 198.102.62.250 (talk) 21:28, 5 February 2007 (UTC).

CRS in GeoRSS[edit]

Untrue to suggest that GeoRSS is restricted to a single coordinate system. True that GeoRSS will default to WGS-84 if no SRS is supplied, but it can definitely support other coordinate reference systems when they are supplied - in fact, GeoRSS supports GML in addition to W3C Geo tags and Simple lat/long tags. DruidSmith (talk) 06:18, 23 December 2007 (UTC)

Examples Latitude vs. Longitude[edit]

I would like to see the examples where the Longitude is greater than +/-90 so that people can quick reference the page to get the lat/lon order correct. —Preceding unsigned comment added by Mrdvt92 (talkcontribs) 22:53, 19 December 2008 (UTC)

This is a great point since the Internet disagrees about what the lon/lat order should be! Jlavezzo (talk) 19:43, 18 May 2011 (UTC)

History[edit]

Do we really need the name of every committe member? This is hardly of interest to anyone except themselves. Geira (talk) 11:22, 14 January 2009 (UTC)

Features using geometries Example[edit]

In the example 'Features using geometries' one property of the <abc:Building gml:id="SearsTower"> feature is:

   <app:extent>
       <gml:Polygon>
           <gml:exterior>
               <gml:LinearRing>
                   <gml:coordinates>100,200</gml:coordinates>
               </gml:LinearRing>
           </gml:exterior>
       </gml:Polygon>
   </app:extent>

I trying to learn, so my understanding of the concepts may not be accurate. Wouldn't the geometry object <gml:Polygon> require that it consist of at least four coordinate pairs (at least a triangle) in the gml element <gml:coordinates></gml:coordinates> with the beginning and ending coordinate pair being identical to 'close' or complete the polygon?

For example: <gml:coordinates>0,0 100,0 100,100 0,100 0,0</gml:coordinates>

It seems as written that the extent of the feature building is a single point.

Thanks All, Ted S —Preceding unsigned comment added by OS Geo Fan (talkcontribs) 15:10, 5 October 2009 (UTC)

Coordinates[edit]

The argument of introducing gml:point because it allows XML DOM access falls short. gml:point does not give separate DOM access to each coordinate since coordinates are still stored in a single string. --Bmaisonny (talk) 17:05, 9 November 2009 (UTC)

Simple Features Profile[edit]

in the general GML model, arbitrary nesting of features and feature properties is not permitted

Is that 'not' supposed to be there? If so, then the remark doesn't add anything at all. —Preceding unsigned comment added by Streapadair (talkcontribs) 15:35, 23 May 2010 (UTC)

Merge from ISO 19136[edit]

Seeing as GML is an ISO Standard, I don't see any benefit from having two separate articles about the same format, even if there are subtle differences in pre-ISO to post. +mt 19:07, 21 March 2011 (UTC)

Agreed - ISO 19136 is GML 3.2.1 [1]PeterParslow (talk) 20:38, 26 March 2011 (UTC)

Yes check.svg Done I agree too, and I've performed the merge. Tijfo098 (talk) 18:28, 17 November 2012 (UTC)