GeoSPARQL Support ?
Holger Knublauch
we had a number of requests for support of GeoSPARQL (or similar) in
TopBraid EDG.
If your group has use cases for this, could you kindly let us know -
either by responding to this mailing list or by mailing me directly?
I suspect that a common use case would be "find all resources that have
geo:lat/long within a given bounding box". This would align well with
the typical Google Maps query where the map displays all items within
the currently visible rectangle. It would also provide a good
approximation of "find me everything within a certain radius".
Are there any other urgent use cases, and how would you rate them
compared to the bounding box scenario?
Background of this question is whether we really need to expose the full
GeoSPARQL feature set or whether we could design an interface with a
much smaller footprint and with less implementation and maintenance
burden. A smaller footprint would allow us to swap the implementation
without breaking existing installations, and of course may get us to a
deliverable faster.
Thanks
Holger
Jan Voskuil
We are helping customers use EDG in the domain of asset management, where GIS is always important.
Our strategy so far has been: use a (top of the bill) GIS system (like ArcGIS Pro) for GIS, and cross-link between that and EDG.
In that way, users are just a mouse click away from the asset detail view (from the GIS-system) or the geo-view (from EDG).
Of course, when cross-queries are desired, some sort of data duplication is needed, either from EDG to the GIS-system, or the other way around.
When data is duplicated from the GIS-system to EDG, use case for GeoSPARQL become relevant.
There is a lot of interest in this, but concrete use cases are difficult to come by.
A heavy user of GeoSPARQL is Kadaster (they do not use EDG). I could ask for some concrete descriptions of what they do.
In general, it is queries like "select all buildings of type Church with construction year < 1900 in the area of municipality X".
Such queries become more and more important with the digitalization of environmental laws and regulations.
I would (of course) applaud any movement in the direction of GeoSPARQL: the more the better.
That said, it is important to be aware of the limitations. Selecting ranges on, say, a bent clothoid (as in a ramp on a freeway intersection) is something that needs highly specialized software, not a generic GeoSPARQL-implementation.
Best, -j
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Holger Knublauch
Hi Jan, others,
let me share some progress. 6.4 will include Jena's GeoSPARQL support and Google Map components in the editor.
In the most basic form, users can open a Map Explorer panel to browser any resource that has geo:lat/long in the visible bounding box:
This is backed by an in-memory geospatial index that can be
generated and updated from data stored in EDG. Only data from
production copies is supported, i.e. the additional triples from
working copies will not be in the index. In terms of performance,
I tried 1 million locations and indexing takes about 25 seconds.
There are SWP elements and SPARQL functions to programmatically
manage those indices, e.g. in scheduled jobs.
This geospatial index can be used via SPARQL using the functions described at
https://jena.apache.org/documentation/geosparql/index.html#property-functions
Query performance seems to be good.
The following finds all locations in a radius of 1000 units
around the map coordinate (10, 20):
Such results can then also be visualized using a Map Results
panel. The Search, SPARQL Results and Asset Lists panels have a
batch operations menu to display any set of resources with their
lat/long:
If anyone has feedback on what else we should support, please let
me know.
Regards,
Holger
Holger Knublauch
Hi Jan, others,
let me share some progress. 6.4 will include Jena's GeoSPARQL support and Google Map components in the editor.
In the most basic form, users can open a Map Explorer panel to browser any resource that has geo:lat/long in the visible bounding box:
This is backed by an in-memory geospatial index that can be
generated and updated from data stored in EDG. Only data from
production copies is supported, i.e. the additional triples from
working copies will not be in the index. In terms of performance,
I tried 1 million locations and indexing takes about 25 seconds.
There are SWP elements and SPARQL functions to programmatically
manage those indices, e.g. in scheduled jobs.
This geospatial index can be used via SPARQL using the functions described at
https://jena.apache.org/documentation/geosparql/index.html#property-functions
Query performance seems to be good.
The following finds all locations in a radius of 1000 units
around the map coordinate (10, 20):
Such results can then also be visualized using a Map Results
panel. The Search, SPARQL Results and Asset Lists panels have a
batch operations menu to display any set of resources with their
lat/long:
If anyone has feedback on what else we should support, please let
me know.
Regards,
Holger
Marco Neumann
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Marco Neumann
KONA
Holger Knublauch
Hi Marco,
no sorry, the Map can only display lat/long values of resources that are stored in a "local" graph. So you would first need to add those triples, maybe temporarily, e.g. using a SPARQL INSERT request.
As usual, you can see the queries that it runs from places like
the Network tab of Chrome dev tools.
Holger
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