vocab proposal: foaf:imageStyleHomepage

[Dan Brickley]

schema fragment:

<rdf:Property rdf:about="http://xmlns.com/foaf/0.1/imageStyleHomepage">
<rdfs:label>imageStyleHomepage</rdfs:label>
<rdfs:comment>A homepage indicative of a style or representational
convention adopted in an image</rdfs:comment>
<rdfs:isDefinedBy rdf:resource="http://xmlns.com/foaf/0.1/"/>
rdfs:domain rdf:resource="http://xmlns.com/foaf/0.1/Image"/>
</rdf:Property>

sample instance data:

<foaf:Image rdf:about="http://www.humanclock.com/livefiles/digital-450/c9b381e4ae92fade30276ec2d709f322.jpg">
<dc:title>11.47</dc:title>
<dc:description>Someone on a beach with pebbles spellling out the time, "11:47"</dc:description>
<foaf:imageStyleHomepage rdf:resource="http://www.humanclock.com/"/>
</foaf:Image>


Goal: make it easy for projects such as Human Clock [1] to discover
images in a particular style. In the case of Human Clock, each picture
generally depicts a person and some representation of a time of day. We
doubtless represent all that explicitly in N3 rules, DAML+OIL and
rdf-calendar, but for a practical start, their project homepage seems a
more convenient way of flagging a group of images. Another example: the
'all your base are belong to us' image hacking style could probably be
picked out by [2], or some of the other URLs strongly associated with it.

Design notes:
This design is purposefully minimalistic. It indirects to the RDF content
the job of naming the image style (via homepage URI), instead of requiring
the invention of new RDF classes and/or properties for each new category
of images. We could have used an rdfs:Class called
<humanclock:PhotoOfPersonWithTimeIndicated> or similar, and maybe we'll
want to do that sort of thing sometimes. For now, a more generic
vocabulary construct allows people to start classifying images against
project homepages without the need to define more RDF vocab each time.

The problem isn't entirely solved, however, since we'd probably want to
query images for other properties relating to their style. For example,
each humanclock-style photo has an associated time. Two options here:
either find or define a property (eg. xyz:depictedTime) that says what you
want (expensive, precise). Or (cheap, less precise) adopt a convention for
using some more well known property (in sample data above, dc:title) as a
carrier. Here, we adopt a convention for using titles to capture the time
as depicted in the photo.

Vocab composition: like many FOAF constructs, the foaf:imageStyleHomepage
property could be considered as being composed of two properties,
foaf:imageStyle (not defined yet) and foaf:homepage. I'd like to write an
RDF vocabulary for making these triangular structures explicit (or I think
DanC might already have one). See
http://rdfweb.org/people/danbri/2001/11/rdfauthor-foaf/foaf-school.png
for a similar structure (foaf:school, foaf:homepage, foaf:schoolHomepage).



Dan



[1] http://www.humanclock.com
[2] http://www.planettribes.com/allyourbase/index.shtml