RDFGeom2d

RDFGeom2d (RDF 2D Geometry Language)

This Version: 1.0
Current Version: 1.1
Revision: 1
Next Revision (preliminary): 2
April 2003
Chris Goad cg@mapbureau.com

RDFGeom2d defines a simple set of RDF classes and properties which represent the basics of two-dimensional geometry. The current version includes only those few primitives needed to support a particular application - an RDF-based facility for mapping - but the vocabulary will be extended in the future. See the RDFMap specification for details about the use of RDFGeom2d for mapping. RDFGeom2d is compliant with the recommendations for RSS 1.0 modules.

Example

Here is a RDFGeom2d file that contains just one point:

<?xml version="1.0" encoding="iso-8859-1"?> 
<rdf:RDF 
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:geom2d="http://nurl.org/0/geom2d/1.0/"
>
     <geom2d:Point>
        <geom2d:x>3</geom2d:x>
        <geom2d:y>4</geom2d:y>
     </geom2d:Point>
</rdf:RDF>

Note that the namespace for RDFGeom2d is http://nurl.org/0/geom2d/1.0/. "nurl" stands for "Not a URL". nurl.org serves as a root for URIs that denote entities - like geographical properties and geometric points - that are not web resources. Of course, in real life, the URI might (or might not) resolve to a web page as well, but this does not affect the intended denotation of the URI when used in RDF.

Here is the list of properties and classes making up RDFGeom2d. Note that classes have uppercase names, and properties lowercase.

Class: Point

Property: x; range = decimal for the domain Point
Property: y; range = decimal for the domain Point

(decimal is the numerical data type defined by XML Schema dataypes)

Class:Box

Property: xmin; range = decimal for the domain Box
Property: xmax; range = decimal for the domain Box
Property: ymin; range = decimal for the domain Box
Property: ymax; range = decimal for the domain Box

When applied to a box, xmin,ymin (resp. xmax,ymax) specify the minimum (resp. maximum) values of the coordinates of points within the box.