Hi Andy and Sören,
Thanks for pointing out the data sources. I've studied the geodata formats
in geonames, LinkedGeoData, DBPedia. There're mainly 2 types of RDF
representation of geo locations (latitude, longitude):
1) wgs84_pos (in gonames, DBPedia and LinkedGeoData)
airports:EGBB rdf:type airports_sc:LargeAirport ;
*geo:lat* "52.4539"^^xsd:float ;
*geo:long* "-1.74803"^^xsd:float
2) Well Known Text Literal (in DBPedia and LinkedGeoData)
lgd-geom:node1000032677 a geom:Geometry ;
*ogc:asWKT* "POINT(7.338818000000001 51.4433324)"^^ogc:wktLiteral .
They are widely used in semantic geodata. I think I'm supposed to support
both format in jena-spatial. If you know more formats in other data
sources, please tell me. Thanks!
Following the way of jena-text, I'm working on the project of jena-spatial
in Google Code [1]. Now the indexing part for 1) has reached a milestone.
I've also made the "Nearby" querying support for 1). The code have been
committed. You can play with the example [2] of querying nearby airports,
borrowed from geoarq [3].
In the next steps, I'll go for 2) and try to implement more query property
functions, such as "Within", "Intersect", and so on. After the mid-term
evaluation in late July, I'm going to work on the assembler implementation
of jena-spatial.
There're also some other issues to be considered carefully.
<1> unit of measurement. The example mentioned above is just using miles
instead of kilometers. Shall we support both, or make things more
complicated to introduce arbitrary unit of measurements?
<2> data source compatibility. For 2), I find that DBPedia uses *
geo:geometry*, while LinkedGeoData adopts *ogc:asWKT *and *geo:geometry. *There
may be more predicates for other data sources. I've made an interface for
jena-spatial to consume all kinds of predicates for 1).
Any comments are welcome!
Best regards,
Ying Jiang
[1] http://code.google.com/p/jena-spatial/
[2]
http://code.google.com/p/jena-spatial/source/browse/trunk/src/main/java/examples/JenaSpatialExample1.java
[3] https://github.com/castagna/GeoARQ
On Mon, Jul 8, 2013 at 9:04 PM, Andy Seaborne <[email protected]> wrote:
> On 02/07/13 04:46, Ying Jiang wrote:
>>
>> Hi,
>>
>> My name is Ying Jiang. I'm the GSoC student for Apache Jena on the
>> project of "jena-sptial". In brief, the project will end up with an
>> ARQ extension to perform simple spatial searches within SPARQL
>> queries. The approach is similar to "jena-text". Many technical
>> details have been discussed during the project application period. I
>> just completed my exams in late June. Now I've set up a svn repository
>> on Google Code [1] and got ready to code. I'd very glad to have Andy,
>> Damian and Stephen as the mentors. You will see the code to be
>> committed there in the coming months. I'd be grateful to your help
>> when I ask questions in the dev mailing list.
>>
>> [1] http://code.google.com/p/jena-spatial/
>>
>> Best regards,
>> Ying Jiang
>>
>
> How's it going?
> What are the immediately goals for the work?
>
> Andy
>
