[gdal-dev] Reading Geometry from text file

[Chaitanya kumar CH]

Moritz,

Did you compile GDAL/OGR with GEOS library support? IsValid() will fail
without this.

I can't tell why get_Area() crashes.

On Tue, Oct 5, 2010 at 3:03 PM, moritzzz <spam at kolix.de> wrote:

>
> Hey guys,
>
> I just started using gdal/ogr and am running into a lot of problems. The
> main one right now comes up when I'm trying to create a geometry from a
> string that I read from a file. The line I'm reading looks like this:
> MULTIPOLYGON(((1 1,5 1,5 5,1 5,1 1),(2 2,2 3,3 3,3 2,2 2)),((6 3,9 2,9 4,6
> 3)))
>
> Now I wrote some c++ code that's supposed to create a OGRMultipolygon in
> which line is the mentioned line from the file:
>
> double* kdTreeMgmtServer::process_polygon(string line, string path) {
>        char* lineArr = (char*) line.c_str();
>
>        OGRGeometry* new_geom;
>        OGRGeometryFactory::createFromWkt(&lineArr, NULL, &new_geom);
>        if (wkbFlatten(new_geom->getGeometryType()) != wkbMultiPolygon) {
>                log_error("not a multipolygon! geometrytype =
> %d\n",new_geom->getGeometryType());
>                return NULL;
>        }
>        if (!new_geom->IsValid()) {
>                log_debug("line is invalid: '%s'\n", line.c_str());
>        }
>        OGRMultiPolygon* poly = (OGRMultiPolygon*) new_geom;
>        poly->get_Area();
> }
>
> The first part seems to work fine, as the geometry is recognized as a
> multipolygon but the validation always fails and poly->get_Area(); causes a
> crash of the code. What am I doing wrong?
>
> Cheers
>
> Moritz
> --
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-- 
Best regards,
Chaitanya kumar CH.
/tʃaɪθənjə/ /kʊmɑr/
+91-9494447584
17.2416N 80.1426E
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