RE: Minor tuning proposal on links related to CRS

+1 Excellent suggestions

From: Martin Desruisseaux [mailto:martin.desruisseaux@geomatys.com]
Sent: Monday, November 07, 2016 3:50 PM
To: public-sdw-comments@w3.org
Subject: Minor tuning proposal on links related to CRS


Hello all

About the "Spatial Data on the Web Best Practices" draft document, I would like to propose two minor editions on the links at the end of chapter 7 (Coordinate Reference Systems) on https://www.w3.org/TR/sdw-bp/#CRS-background. The document redirects the reader to Spatial Reference (http://spatialreference.org/) and EPSG.io (http://epsg.io/) web sites for CRS definitions. But the definitions on those web sites sometime differ from the OGC and EPSG definitions regarding axis order and units of measurement. The definitions on those web sites are rather the ones used by GDAL (the library behind MapServer, PostGIS and QGIS among others). Maybe the use of those definitions was an intentional choice? (e.g. it was the choice of GeoJSON before they deprecated CRS in the IETF standard, precisely because they were not OGC/EPSG definitions). If the document rather aims to reference OGC/EPSG definitions, then should the document links to the authoritative source, which is http://epsg-registry.org/ ? It does not mean to remove the other links, but maybe a little explanatory text like below would be appropriate?

Instead of:

Lists of CRS are available from the Open Geospatial Consotium CRS Register, Spatial Reference and EPSG.io (an open-source web service which simplifies discovery of coordinate reference systems utilized worldwide).

Maybe something like below?

The authoritative source of CRS definitions is the EPSG registry. Those definitions are also available from the Open Geospatial Consotium CRS Register. Alternative source of CRS definitions are Spatial Reference and EPSG.io (an open-source web service which simplifies discovery of coordinate reference systems utilized worldwide). But those alternatives sometime uses different axis order and units of measurements than the authoritative definitions.

About the link to the Apache SIS documentation in the last paragraph (thanks!), would you mind changing the http://sis.staging.apache.org/book/en/developer-guide.html URL to http://sis.apache.org/book/en/developer-guide.html (i.e. just remove the "staging" part in the URL)?

    Best regards,

        Martin Desruisseaux