RE: GML or WKT in GeoSPARQL

Hi Frans,

The Ordnance Survey linked data (which doesn't currently use GeoSPARQL, but uses a very similar ontology made in house - we will migrate over time) opted for GML. Our decision was largely because it is the 'format of choice' for many of our main products and also favoured by INSPIRE.

Interesting I had an issue with ogr2ogr when converting a shape file to GML that I couldn't control the decimal places and there were all sort of strange round errors occurring (in EPSG:27700).

With POSTGIS I had trouble loading a shape file that contained mixed geometry types. Either post gis loaded everything as multisurface or threw an error if I tried to load the simple geometries. I opted for FME follow by some XSL in the end.

Another option - and I *think* it's allowed by GeoSPARQL is GeoJSON.

John

Dr John Goodwin
Principal Scientist
Research, Ordnance Survey
Adanac Drive, SOUTHAMPTON, United Kingdom, SO16 0AS
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From: Frans Knibbe | Geodan [mailto:frans.knibbe@geodan.nl]
Sent: 11 April 2013 10:07
To: public-locadd@w3.org
Subject: GML or WKT in GeoSPARQL

Hello,

The GeoSPARQL standard allows for two ways of representing geometry: GML or WKT. I have always thought WKT to be the preferred format, because of its greater simplicity and its wider software support. But now I have discovered a drawback of WKT: It does not seem possible to control coordinate precision when transforming geometry to WKT in PostGIS. Unlike the function ST_AsGML(), the PostGIS function ST_AsText() does not have a parameter maxdecimaldigits. This can cause data to be bloated as well as erroneous.

What do you think?
Would it make sense to investigate the pros and cons of WKT and GML for serialisation of geometry in this group?

Regards,
Frans
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