Is the EllipsoidalCS element missing from the CRS84 definition?

[ghobona]

EllipsoidalCS element is missing from CRS84 definition.

http://www.opengis.net/def/crs/OGC/1.3/CRS84

[ghobona]

@pebau

Cc: @joanma747

[pebau]

@ghobona I see - we took that from the WMS spec, maybe there was an update. Who could provide us with the content? Then we can add it on short notice, no problem.

[ghobona]

@pebau

The information is there on Table B.2 of the WMS 1.3 spec (06-042).

Comparing the CRS84 definition to that of EPSG:4326, I notice that the <ellipsoidalCS> element in EPSG:4326 provides the information about axes. So I will ask the CRS DWG to review and if necessary to provide the content.

[ghobona]

@RogerLott Could the CRS DWG please review the CRS84 definition and confirm whether or not an <ellipsoidalCS> element is missing?

[RogerLott]

Hi Gobe, Yes it is missing from the GML which gives: <ellipsoidalCS> <empty/> </ellipsoidalCS> It should be: <gml:ellipsoidalCS> <gml:EllipsoidalCS gml:id="epsg-cs-6424"> <gml:metaDataProperty> <epsg:CommonMetaData> <epsg:type>ellipsoidal</epsg:type> <epsg:informationSource>OGP</epsg:informationSource> <epsg:revisionDate>2015-05-22</epsg:revisionDate> <epsg:changes> <epsg:changeID xlink:href="http://www.opengis.net/def/change-request/EPSG/0/2008.045"/> <epsg:changeID xlink:href="http://www.opengis.net/def/change-request/EPSG/0/2015.018"/> </epsg:changes> <epsg:isDeprecated>false</epsg:isDeprecated> </epsg:CommonMetaData> </gml:metaDataProperty> <gml:identifier codeSpace="IOGP">http://www.opengis.net/def/cs/EPSG/0/6424</gml:identifier> <gml:name> Ellipsoidal 2D CS. Axes: longitude, latitude. Orientations: east, north. UoM: degree </gml:name> <gml:remarks> Used in geog2D CRSs for some web mapping: CS code 6422 recommended. Coordinates referenced to this CS are in degrees. Any degree representation (e.g. DMSH, decimal, etc.) may be used but that used must be declared for the user by the supplier of data. </gml:remarks> <gml:axis> <gml:CoordinateSystemAxis gml:id="iogp-axis-220" uom="http://www.opengis.net/def/uom/EPSG/0/9122"> <gml:descriptionReference xlink:href="http://www.opengis.net/def/axis-name/EPSG/0/9902"/> <gml:identifier codeSpace="EPSG">http://www.opengis.net/def/axis/EPSG/0/220</gml:identifier> <gml:axisAbbrev>Lon</gml:axisAbbrev> <gml:axisDirection codeSpace="EPSG">east</gml:axisDirection> </gml:CoordinateSystemAxis> </gml:axis> <gml:axis> <gml:CoordinateSystemAxis gml:id="iogp-axis-221" uom="http://www.opengis.net/def/uom/EPSG/0/9122"> <gml:descriptionReference xlink:href="http://www.opengis.net/def/axis-name/EPSG/0/9901"/> <gml:identifier codeSpace="EPSG">http://www.opengis.net/def/axis/EPSG/0/221</gml:identifier> <gml:axisAbbrev>Lat</gml:axisAbbrev> <gml:axisDirection codeSpace="EPSG">north</gml:axisDirection> </gml:CoordinateSystemAxis> </gml:axis> </gml:EllipsoidalCS> </gml:ellipsoidalCS> The same element is not missing from the definition of CRS84h <http://www.opengis.net/def/crs/OGC/0/CRS84h> . However in the CRS84h <ellipsoidalCS> element there are a couple of minor errors (looks to me likely introduced in manual editing, e.g. <epsg:show> is not in the EPSG data model of CS attributes and there are several instances of 'IOGP' which should be 'EPSG'). I will leave someone else to correct those. In both of these entries the only element I have checked is <ellipsoidalCS>. Roger From: ghobona ***@***.*** Sent: 11 August 2022 09:53 To: opengeospatial/NamingAuthority Cc: RogerLott; Mention Subject: Re: [opengeospatial/NamingAuthority] Is the EllipsoidalCS element missing from the CRS84 definition? (#84) @RogerLott <https://github.com/RogerLott> Could the CRS DWG please review the CRS84 <http://www.opengis.net/def/crs/OGC/1.3/CRS84> definition and confirm whether or not an <ellipsoidalCS> element is missing? — Reply to this email directly, view it on GitHub <#84 (comment)> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGUS2WHYANETIUIGGWSSUODVYS5QPANCNFSM4ZVHBGSQ> . You are receiving this because you were mentioned. <https://github.com/notifications/beacon/AGUS2WEP5GVUGED5YZOHT43VYS5QPA5CNFSM4ZVHBGS2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOJA4U32A.gif> Message ID: ***@***.***>

[ghobona]

@RogerLott Thanks for the review. I'll prepare a draft revision for the OGC-NA to consider and approve.

[ghobona]

A proposed revision is at https://github.com/opengeospatial/NamingAuthority/tree/crs84_ellipsoidalcs/incubation/crs84

The associated Pull Request is #207

As I was preparing the proposal, I discovered that the referenced EPSG.xsd file is no longer available. So it is not possible to validate the structure of the XML file by XSD. The EPSG.xsd file has the namespace urn:x-ogp:spec:schema-xsd:EPSG:0.11:dataset. I presume it is a very old version of the schema, since the 2020 version has the namespace urn:x-ogp:spec:schema-xsd:EPSG:2.1:dataset.

The topic will be discussed during the OGC-NA session on Monday 3rd October at 15:00 SGT.

[RogerLott]

The latest version of the EPSG XML schema is v2.2 . A download is available through https://epsg.org/gml-schema.html