Re: How to represent geographic coordinates for maps

Hi,
Why do you say that GeoSPARQL is just about places? GeoSPARQL (and
stSPARQL) allow the representation of geometric information encoded
according to the WKT and GML standards (so you can have points,
linestrings, polygons, multipoints etc.). To my understanding, you can
safely use the vocabulary proposed by GeoSPARQL (I don't see any reasons
not to do so).

So, your example would be as follows:

prefix geo: <http://www.opengis.net/ont/geosparql#>

my:resource
        a ex:Map ;
        dc:title "The Marauder's Map" ;
        my:hasSpatialExtent my:resourceGeo .

my:resourceGeo
        a geo:Geometry ;
        geo:hasGeometry
"<http://www.opengis.net/def/crs/OGC/1.3/CRS84>POLYGON((45.33
-13, 45.33 49, 45.58 49, 45.59 -13, 45.33 -13))"^^geo:wktLiteral .

If you prefer to use another coordinate reference system you can use a
different URI and modify the coordinates appropriately.

Best,
Kostis

===================================================
Kostis E. Kyzirakos, PEng
National & Kapodistrian University of Athens
Department of Informatics & Telecommunications
Management of Data & Information Knowledge Group
Panepistimioupolis, Ilissia
GR-15784 Athens, Greece
Tel: +30.210.727.5159
Fax: +30.210.727.5214
e-mail:  kkyzir@di.uoa.gr
===================================================


On Fri, Jul 12, 2013 at 12:51 PM, Konrad Höffner <
konrad.hoeffner@uni-leipzig.de> wrote:

> Hi Lars,
>
> To question 3: First, I think that depending on the projection and
> scale, a rectangle on a map is not/only nearly representable by a
> rectangle in geocoordinates.
> Furthermore, the representation you chose (""W 13' - E 49' / N 45°58' -
> N 45°33'""") is not very easily machine-readable because you code a
> rectangle into a single literal and also use a coordinate notation that
> needs additional parsing.
> Maybe polygons like the ones used in LinkedGeoData would be helpful? A
>
> Regards,
> Konrad
>
> On 12.07.2013 11:14, Svensson, Lars wrote:
> > All,
> >
> > At the German National Library we are currently looking into how to
> represent coordinates for maps and we need some advice on which
> representation would be most useful for the community.
> >
> > While looking at publishing coordinates for places in the library
> authority data, we also started looking at how to represent the geographic
> extent of maps. I came across three vocabularies that could be useful for
> that:
> > 1) the (library-specific?) properties scale:
> http://rdvocab.info/Elements/scale, projection:
> http://rdvocab.info/Elements/projectionOfCartographicContent and
> coordinates: http://rdvocab.info/Elements/coordinatesOfCartographicContentfrom RDA (Resource Description and Access)
> > 2) the properties from wgs84_pos
> > 3) the properties from geosparql
> >
> > If I have understood things correctly, only the RDA ones are applicable
> directly for a map, whereas wgs84 and geosparql really are about places and
> not about maps, so that you would need to introduce a level of indirection
> to use them directly for maps. A (made-up) example:
> >
> > my:resource a ex:Map ;
> >         dc:title "The Marauder's Map" ;
> >         rdvocab:coordinatesOfCartographicContent """W 13' - E 49' / N
> 45°58' - N 45°33'""" .
> >
> > my:resource a ex:Map ;
> >         dc:title "The Marauder's Map" ;
> >         dct:coverage [ a wgs84_pos:SpatialThing ;
> >                 wgs84_pos:lat_long """ W 13' - E 49' / N 45°58' - N
> 45°33'""" ;
> >                 .
> >         ] .
> >
> > So my three questions:
> > 1) Is my interpretation of the use of wgs84 for maps correct?
> > 2) Are coordinates for maps of any use at all to this community?
> > 3) (If the answer to 2) is yes): which representation would be the best
> for your use cases?
> >
> > Thanks in advance for any insight,
> >
> > Lars
> >
> > ***Lesen. Hören. Wissen. Deutsche Nationalbibliothek***
> > ***Reading. Listening. Understanding. German National Library***
> >
>
>
>
>