On 11.03.2015 05:40, Tom Morris wrote:
On Tue, Mar 10, 2015 at 6:41 PM, Markus Krötzsch <markus@semantic-mediawiki.org mailto:markus@semantic-mediawiki.org> wrote:
For example, you can see that Portugal has a lot of lighthouses while Spain has almost none -- maybe we need to look at our data there ;-)Perhaps it's a language confusion issue, but does Spain really have few lighthouses? That would seem VERY unusual for a territory with an extensive coastline.
No, you are right: this is of course an issue in the completeness of our data. If you zoom in to Europe, you can see that some countries have costs full of lighthouses, while others seem to lack them almost completely. I think it clearly shows that a lot of our data comes from Wikipedias (in some specific language).
Where does Wikidata sit in that mix? How does it compare with DBpedia, Freebase, Wikipedia, or even *real* data sources like official governmental lists of navigational aids for mariners at sea?
Good question. I guess that we could have a much better coverage for some of the obvious holes in our data, e.g., by adding classificaiton information based on Spanish Wikipedia categories.
Independent of where it sits now, what where does it aspire to sit?
The uncontested target would be:
* Every lighthouse that is found in any Wikipedia (hence in Wikidata) should be "instance of lighthouse" and have coordinates and country defined.
A possible target to discuss would be to add:
* Every lighthouse should be in Wikidata.
Whether or not this makes sense depends on how many lighthouses there really are. Maybe we are not so far from completeness. Lighthouses are prominent landmarks of historic, nautic, and touristic interest, so should be valid Wikipedia topics anyway. Moreover, they tend to change very little over time, so data maintenance is relatively easy.
Note that this is quite different from streets, which change names all the time, get created, demolished, and merged, and are much larger in number. From these properties, I think OSM is much better suited for managing this data for now.
In view of the current developments towards Wikidata query support, a tangible goal would be to set up integrated query services that provide a joint view of the data from OSM and Wikidata without physically moving large quantities of data from one to the other.
Markus