[PROJ] [EXTERNAL] [gdal-dev] Static/Dynamic datum problems

Kristian Evers kreve at sdfe.dk
Tue Jun 25 01:16:20 PDT 2019

Hi Martin,

That is good news. I find it hard to keep up with the standards when they are still in drafts so I’m glad you can give us an update from time to time. I hope that you are right and the Simple Features model will be expanded to include the temporal dimension as well. If that is the case there’s light at the end of the tunnel :-) It is probably still going to take quite a while before the complete GIS software stack absorbs the updated standards but that is to be expected with such a radical change.


From: PROJ <proj-bounces at lists.osgeo.org> On Behalf Of Martin Desruisseaux
Sent: 25. juni 2019 09:41
To: proj at lists.osgeo.org
Subject: Re: [PROJ] [EXTERNAL] [gdal-dev] Static/Dynamic datum problems

Hello all

ISO 19111:2019 (Referencing by coordinates) already includes the timestamp of coordinates. The standard defines a CoordinateMetadata class with two properties:

  *   crs: Identifier of the coordinate reference system to which a coordinate set is referenced.
  *   coordinateEpoch: Epoch at which coordinate referenced to a dynamic CRS are valid.

ISO 19107 (the standard that defines geometry objects) has been revised. I did not yet had a chance to look closely at it, but last time I attended to the discussions at OGC my understanding was that the new geometry objects would be associated to ISO 19111 CoordinateMetadata class (and consequently include the coordinate epoch) instead than to only the CRS.

Simple features are derived from ISO 19107 by the same author. I think I have seen emails on OGC mailing list about drafts available, but did not yet had a chance to look at them. At least, the current Simple Feature editor is well aware of this coordinate epoch topic since he was present at OGC meetings that debated about it. So I guess there is good chances that coordinate epoch will be present in some way in simple features (but did not verified).


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