CRS Resolver Discussion

Overview

This page collects discussion, as well as open and resolved issues, regarding the OGC resolver. Generally speaking, n-D CRS handling is a young, very dynamic field. Therefore, sometimes new requirements come in from stakeholders.

Issues Open

(none currently)

Issues Resolved

Abbreviation Changes in EPSG Database

  • Axis abbreviation "long" has been changed to "lon" in EPSG geodetic dataset after 8.5. This is not an incompatible change since axis abbreviations are not identifiers and do not affect numerical computation; they are more like metadata. But some software are nevertheless affected by this change. For this reason, upgrading the EPSG geodetic dataset version referenced by /0/ has been temporarily delayed. Of course this entails that other EPSG changes, like new CRSs introduced, are not available this way either.
  • *Preliminary resolution*:
    • the EPSG database continues to get updated in OGC; updated versions available by indicating the particular version, such as http://www.opengis.net/def/crs/EPSG/8.9.2/4326
    • version indicator "0" (earlier indicating "latest version" as an informal, non-normative convention) is temporarily fixed to version 8.5.2
  • final solution, as per OGC-NA decision in March 2019:
    • version "0" shall always point to the latest version of the corresponding EPSG definition. (Caveat: this may imply unnoticed changes by EPSG)

Case Sensitivity

  • Request: (Simon Cox) I just discovered that the URI redirects associated with EPSG CRS parameters are case-sensitive, so http://www.opengis.net/def/crs/EPSG/0/5711 and http://www.opengis.net/def/crs/epsg/0/5711generatedifferent responses: the former goes to SECORE, and the latter to the EPSG Indicio registry. This clearly is undesirable. They should go to the same place, and that place should be SECORE.
  • Resolution: There has been discussion with OGC since April 2016, but no authoritative decision has been made. Therefore, we continue using IETF 2141 (referenced by IETF 5165), sections 5 and 6: https://tools.ietf.org/html/rfc2141 implying that SECORE should be case sensitive, as would be anything after the “ogc” namespace identifier. -- PeterBaumann - 19 Sep 2016

Redirection to the Resolver

  • Request: The redirection mechanism is currently not working as expected and it seems that only EPSG related definitions actually redirected to SECORE:
  1. http://www.opengis.net/def/axis/OGC/1.0/East
  2. http://www.opengis.net/def/crs/
  3. http://www.opengis.net/def/crs/OGC/
  4. http://www.opengis.net/def/crs/ -- PieroCampalani - 25 Nov 2013
  • Resolution:OGC has corrected URL redirection In October 2016.

Schema

CRSdefinitionResolver Web Utilities

I Attachment Action Size Date Who Comment
indexCrs.pngpng indexCrs.png manage 44 K 01 Jul 2014 - 17:16 PieroCampalani Depiction of a 3D Index CRS.
temporalCrs.pngpng temporalCrs.png manage 53 K 01 Jul 2014 - 17:17 PieroCampalani Depiction of a Time CRS.
Topic revision: r4 - 12 Jun 2019, PeterBaumann
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