On 12/09/12 23:10, Marco Neumann wrote:
I would say yes the interesting bits are done by JTS. we used another LGPL
index for geosparql.org.
I think Jena deserves a dedicated file based indexer to support the full
OGC geosparql standard but that said the task should not be underestimated.
(a certain amount for recall from my last look at GeoSPARQL ...)
There are four parts:
1/ Persistent index (r-tree, quadtree,...)
2/ Algorithms + Geo objects layer
inc parsers and a Java library to handle geo data
3/ GeoSPARQL specifics - transformation, query rewrite etc etc
4/ Creating the index, either externally or coupled to a dataset.
There don't all have to be perfect and complete on day 1 to provide
users with useful GeoSPARQL capability. For example, an in-memory index
gets a certain amount of scale over brute force search of all data and
not all uses are a billion polygons.
Parliament?
opensahara->useekme (uses JTS inside?)
Lucene spatial? (I presume, not having looked, this is a z-ordering - we
could adapt the B+Trees to do it [1]
Andy
(yes - I'd love to have a go at the persistent index if I could get some
sort of funding :-)
[1] http://en.wikipedia.org/wiki/UB-tree
but
http://www.scholarpedia.org/article/B-tree_and_UB-tree#UB-trees_for_Multidimensional_Applications
has pictures!
On Wed, Sep 12, 2012 at 5:59 PM, Rob Vesse <rve...@yarcdata.com> wrote:
If I read the documentation correctly it can optionally use the JTS
library (which yes is LGPL and so no go for Apache projects) if that
library is needed, it can be used without.
I'm not sure if the extra features that JTS provides are necessary for a
GeoSPARQL implementation because I'm not up to speed on exactly what
GeoSPARQL requires
Rob
On 9/12/12 2:51 PM, "Marco Neumann" <marco.neum...@gmail.com> wrote:
it uses the JTS Topology Suite indexer which hasn't been updated for a
while but is open source under the LGPL license.
On Wed, Sep 12, 2012 at 5:42 PM, Rob Vesse <rve...@yarcdata.com> wrote:
I remember some discussions a while back about one of the barriers to
implementing GeoSPARQL in Jena being the lack of a good indexing
library to
use
I notice that Lucene 4.0 has a new Spatial module -
http://lucene.apache.org/core/4_0_0-BETA/spatial/index.html which is
itself built on another library Spatial4j which is ASL licensed
Would these be sufficient pieces to get us started? I haven't looked in
detail as to whether these libraries provide the specific geospatial
primitives and functions we'd need to implement GeoSPARQL
Rob
--
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Marco Neumann
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