RDF Site Summary 1.0 Modules: dcterms:spatial

 Author

Tom Longson http://nym.igargoyle.com/

Description

Dublin Core proposed a format for holding geospatial data, but I found in application the metadata needed to be more specific in order to become a usable standard. Desribed below is a set of geospatial data metadata values, which can be used for web logs, articles, and publishing geospatial data online.

Model

<dcterms:spatial> Elements:

Elements of <dcterms:spatial>

Name
The title of the location in which the post was published or the location of a picture if the spatial data is in an .

Description
The description of your location.

Projection
The geospatial projection used. As far as I know, WGS84 is the standard projection. Unless I learn otherwise, please default to WGS84 if no projection is provided for simplicity's sake.

North
Distance north or south of the equator, measured on a meridian. Same as Latitude. This number is expressed in degrees.

East
Longitude in degrees east of the Greenwich Meridian, with any number of deciamal places. This number is expressed in degrees.

Elevation
The distance from sea level. This number is expressed in meters.

Accuracy
The geospatial accuracy of your coordinates. If you are purposely being fuzzy about your location, pick a point near your location and under accuracy, put an aproximate distance to your real location. This number is expressed in meters.

Speed
The temporal speed, usually obtained from a GPS unit. This number is expressed in meters.


Here is an example:

<dcterms:spatial>
    <rdf:Description>
        <dcterms:name>Nym's Home</dcterms:name>
        <dcterms:description>Where I sleep and eat.</dcterms:description>
        <dcterms:projection>WGS84</dcterms:projection>
        <dcterms:north>34.103832</dcterms:north>
        <dcterms:east>118.158774</dcterms:east>
        <dcterms:elevation>666</dcterms:elevation>
        <dcterms:accuracy>22.34</dcterms:accuracy>
        <dcterms:speed>1.781296</dcterms:speed>
    </rdf:Description>
</dcterms:spatial>

Or, more closely to the original <dcterms:spatial> specification,

<dcterms:spatial>
    <dcterms:point>
        <rdf:value>
            name="Nym's Home"; description="Where I sleep and eat."; 
            projection="WGS84"; north=34.103832; east=118.158774; 
            elevation=666; accuracy=22.34; speed=1.781296
        </rdf:value>
    </dcterms:point>
</dcterms:spatial>

Another, less complicated example is below:

<dcterms:spatial>
    <rdf:Description>
        <dcterms:name>Mischiefgurl.com</dcterms:name>
        <dcterms:description>Los Angeles based blog.</dcterms:description>
        <dcterms:north>34.005794</dcterms:north>
        <dcterms:east>118.39611</dcterms:east>
    </rdf:Description>
</dcterms:spatial>


Verbose Spatial Example
The dcterm:spatial elements are in blue. Also included in this example is the Img Module metadata which can be used to describe a photograph, in this case the geocoordinates provided by dcterms:spatial describes the location where the photograph was taken. This example can also be viewed at http://nym.igargoyle.com/example.xml.


<?xml version="1.0" encoding="UTF-8"?>

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
        xmlns="http://purl.org/rss/1.0/"
        xmlns:rss="http://purl.org/rss/1.0/"
        xmlns:dc="http://purl.org/dc/elements/1.1/"
        xmlns:img="https://igargoyle.com/rss/1.0/modules/img"
        xmlns:dcterms="http://purl.org/dc/terms/"
        xmlns:record="https://igargoyle.com/rss/1.0/modules/record"
        xmlns:im="http://purl.org/rss/1.0/item-images/">

    <channel rdf:about="https://igargoyle.com/">
        <title>Image Blog Example</title>
        <link>https://igargoyle.com/</link>
        <description>An example RSS channel for image blogs.</description>
        <image rdf:resource="http://example.igargoyle.com/images/logo.gif"/>
        <img:images>
                <rdf:Alt>
                        <rdf:li rdf:resource="http://example.igargoyle.com/images/logo.gif"/>
                        <rdf:li rdf:resource="https://igargoyle.com/city.jpg"/>
                </rdf:Alt>        
        </img:images>
    </channel>

        <!-- the logo we're using. if you omitted this and the below, no logo would be displayed -->
        <!-- use RSS image element for parsers that do not understand
        http://purl.org/rss/1.0/modules/image# note that this causes a duplication
        of RDF information about http://www.example.com/images/logo.gif which
        could cause issues for some parsers if there is an inconsistency -->
        <image rdf:about="http://www.example.com/images/logo.gif">
                <title>igargoyle</title>
                <link>https://igargoyle.com/</link>
                <url></url>
                <!-- include http://purl.org/rss/1.0/modules/image#
                for parsers with partial support -->
                <img:url>http://example.igargoyle.com/images/logo.gif</img:url>
                <dc:format>
                        <rdf:Description>
                                <dcterms:IMT>image/gif</dcterms:IMT>
                                <dcterms:extent>4023</dcterms:extent>
                        </rdf:Description>
                </dc:format>
                <img:dimensions>
                        <rdf:Description>
                                <img:unit>px</img:unit>
                                <img:width>88</img:width>
                                <img:height>31</img:height>
                        </rdf:Description>
                </img:dimensions>
                <description>This is the logo for this example.</description>
                <img:link>http://example.igargoyle.com/</img:link>
                <img:longdesc>http://example.igargoyle.com/image_example.html</img:longdesc>
                <img:event>none</img:event>
        </image>

        <!-- the logo we're using. if you omitted this and the above, no logo would be displayed -->
        <img:image rdf:about="http://example.igargoye.com/images/logo.gif">
            <rdf:Description>
                <dc:format>
                        <rdf:Description>
                                <dcterms:IMT>image/gif</dcterms:IMT>
                                <dcterms:extent>4023</dcterms:extent>
                        </rdf:Description>
                </dc:format>
                <img:dimensions>
                        <rdf:Description>
                                <img:unit>px</img:unit>
                                <img:width>88</img:width>
                                <img:height>31</img:height>
                        </rdf:Description>
                </img:dimensions>
                <description>This is the logo for this example.</description>
                <img:link>http://example.igargoyle.com/</img:link>
                <img:longdesc>http://example.igargoyle.com/image_example</img:longdesc>
                <img:animation>no</img:animation>
                <img:event>none</img:event>
            </rdf:Description>
        </img:image>

        <!-- this is the first image -->
<item record:uuid="1030176902" rdf:about="http://example.igargoyle.com/img/permalink/1030176902.html">
    <title>San Francisico, Fog Rolling in</title>
    <dc:date>Sat Aug 24 2002 08:00 AM</dc:date>
    <dc:subject>San Francisco</dc:subject>
    <im:image>https://igargoyle.com/subject/sanfrancisco.gif</im:image>
    <dc:creator>Burtonator</dc:creator>

    <dcterms:spatial>
        <rdf:Description>
            <dcterms:name>The Top of Moraga Park</dcterms:name>
            <dcterms:description>It's at the intersection of 14th and Moraga in the sunset.</dcterms:description>
            <dcterms:projection>WGS84</dcterms:projection>
            <dcterms:north>39.04</dcterms:north>
            <dcterms:east>-95.69</dcterms:east>
        </rdf:Description>
    </dcterms:spatial>

    <description>One of the best parks in the city with awesome views and nobody knows about it.</description>
    <img:url>https://igargoyle.com/city.jpg</img:url>
    <img:camimage>https://igargoyle.com/subject/digitalcam.gif</img:camimage>
    <img:cam>Nikon Coolpix 550</img:cam>
    <img:film>Flash Card</img:film>
    <img:lense>Factory Default</img:lense>
    <img:filters>none</img:filters>
    <img:manipulated>no</img:manipulated>
    <img:link>http://example.igargoyle.com/image_example.html</img:link>
    <img:event>none</img:event>
    <dc:format>
        <rdf:Description>
                <dcterms:IMT>image/pjpeg</dcterms:IMT>
                <dcterms:extent>8029</dcterms:extent>
        </rdf:Description>
    </dc:format>
    <img:dimensions>
        <rdf:Description>
            <img:unit>px</img:unit>
            <img:width>640</img:width>
            <img:height>480</img:height>
        </rdf:Description>
    </img:dimensions>
</item>

</rdf:RDF>


Below is an excerpt from RDF Site Summary 1.0 Modules: Spatial, which is the original specification for dcterms:spatial. I based everything here as closely to the original specification but added more specific values and tried to make the documentation more explicit.

...

4.6.1 <dcterms:spatial>

Spatial is a refined element which is a sub-property of the DC Coverage element and is defined as:

Name: spatial
Label: Spatial
Definition: Spatial characteristics of the intellectual content of the resoure.

There are several encoding schemes for Spatial, several of which could be the default one for RSS. However since it's not clear which one it is recommended that if Spatial is used it's encoding scheme is made clear for example:


  <dcterms:spatial>
    <dcterms:Point>
      <rdf:value>
        name="KS, Topeka"; projection=WGS84; north=39.04; east=-95.69
      </rdf:value>
    </dcterms:Point>
  </dcterms:spatial>

  <dcterms:spatial>
    <dcterms:Box>
      <rdf:value>
        name=Western Australia; 
        northlimit=-13.5; southlimit=-35.5; 
        westlimit=112.5; eastlimit=129
      </rdf:value>
    </dcterms:Box>
  </dcterms:spatial>

  <dcterms:spatial>
    <dcterms:TNG>
      <rdf:value>7008171</rdf:value>
      <rdf:label>Yorkshire (region (general))</rdf:label>
    </dcterms:TNG>
  </dcterms:spatial>

...