[gdal-dev] Binary Predicates in SQLite SQL dialect

[Even Rouault]

Le mardi 30 septembre 2014 20:20:14, Andre Vautour a écrit :
> Hi all,
> 
> I am trying to use a geometry binary predicate (ST_Intersects) in
> ExecuteSQL() with the SQLite dialect and keep getting back an
> "ST_Intersect function does not exist" error back from SQLite.
> 
> GDAL is built with SpatiaLite (HAVE_SPATIALITE is defined), but I
> believe the problem is that SpatiaLite is built without GEOS in our
> case, so those predicate functions end-up not being available in
> SpatiaLite. The end result is that OGRSQLiteRegisterSQLFunctions does
> not add the OGR-based predicate functions as SpatiaLite is present, but
> SpatiaLite does not contain the predicate functions.
> 
> I would build SpatiaLite with GEOS support, but unfortunately its LGPL
> licensing is too restrictive for our application. So, would it make
> sense to change the logic in OGRSQLiteRegisterSQLFunctions to account
> for the case of SpatiaLite being built without GEOS?

Andre,

That makes sense. I guess that can only be checked at runtime though, probably 
by issuing a ST_Intersects() and checking the error code.

I'd note that the spatial predicates in OGR geometry are also based on GEOS. 
Except OGRGeometry::Intersects() that has a simplified implementation based on 
bounding box intersection when GEOS is not available.

Some time ago, I had a look at boost geometry (
http://www.boost.org/doc/libs/1_56_0/libs/geometry/doc/html/index.html ). That 
could be used as an alternative backend to GEOS for most predicates and 
functions returning geometries, and the boost licence is a modified X/MIT.

Even

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