[OSM-dev] Semantic information for SVG maps created with Osmarender
s.queisser at freenet.de
Sun Sep 20 21:27:34 BST 2009
Some time ago I told you that I'm developing a label placement optimizer
for SVG maps created with Osmarender (OSMLabelOptimizer, see ). What
I noticed while coding the tool was that Osmarender removes some
information from the original osm data when converting to SVG. For
example it is not trivial to find the label attached to a point or area
feature. Nevertheless it is possible, but I had do do some ugly things
(e.g. comparing coordinates and css styles, etc.). What I therefore need
is semantic information attached to SVG map (why only using the SVG
metadata tag for copyright information?).
Finally, as described on , I came to OWL . So far I created an OWL
ontology which can be used to describe an SVG map  and a patch  to
give Osmarender the ability to create an OWL description using my
ontology. The description contains information about the features
contained in the map, with links to the linkedgeodata project 
(provides an RDF description for all OSM data). Each feature is also
connected to it's labels and the SVG elements which draw them.
If you still ask yourself what this is all about, here are some more
ideas why a semantic description of SVG maps could make sense:
* If you create your SVG map with Osmarender and send it to someone else
he not only gets a picture, but he gets the whole information
available from OSM connected to the map. Perhaps in the future there
will be a java application where he can load the SVG map and get a
list of all features shown on the map or there will be an application
which uses the metadata to calculate and show a route from one point
on the map to another point. Or perhaps the user is just interested in
the opening hours of a museum shown on the map.
* Semantic search engines could index these SVG maps and users could run
complex queries to find maps.
* A Osmarender SVG map editor that makes it easy to add something like
an highlighted route or a circle focusing on a special point feature.
For this editor it would also be possible to give the user the ability
to enrich the map with labels giving addtional information that is so
far not shown on default SVG maps (e.g. speed signs, opening hours,
* Especially postprocessing of SVG maps will be much more easier,
because we now have all the information we need.
What do you think about this approach? If you are interested, please
visit my page , test the patch  and give feedback to me.
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