[gdal-dev] Open source vector geoprocessing libraries?

Mateusz Loskot mateusz at loskot.net
Wed Jan 13 15:19:50 EST 2010

Jan Hartmann wrote:
> On 13-1-2010 2:33, Mateusz Loskot wrote:
>> OGR does not provide any spatial indexing layer common to various 
>> vector datasets. For many simple formats it performs the 
>> brute-force selection.
> Just curious, would it make sense / be possible to implement indexing
>  in OGR, something like a generalized version of Mapserver's shptree,
>  the "quadtree-based spatial index for a shapefiles"?

This implementation of index comes from Shapelib made by Frank.
The very same bits of Shapelib are used in MapServer and OGR,
namely .qix spatial index file support.
So, it's already there but for Shapefiles only.

Back to the question, I'm personally sceptic.
Recalling example with processing two layers, one from DBMS and one from
file-based data source, how it would be supposed to work?
...common .qix file generated for DBMS data source?

In my opinion, this kind of functionality is out of scope of OGR.
I see OGR as a data provider. OGR is basically a translation library
that reads from one data source and writes to another data source
providing set of reasonably limited features to process data during
translation - a common denominator for popular vector spatial
data formats.

IMHO, it's misunderstanding to consider OGR fully featured data model
and I/O engine to read, write, process and analyse spatial vector data,
especially if performance is a critical factor. IMHO, there are too many
compromises in OGR.

Best regards,
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org

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