# [geos-devel] Problems creating polygons with holes

Darren Carman darren.carman at infoterra-global.com
Mon Jun 28 06:05:22 EDT 2004

```defs:
typedef struct boundaryPt {
double x;
double y;
};
typedef vector<boundaryPt>    boundary;
typedef vector<boundary>      boundaryList;
typedef vector<boundaryList>  polygonList;

class members used:
polygonList       ptPolygons;
string tmpStr;
string errMsg;

class function:
string c_polygon_gml::WKTString(void) {
TRACE_FUNC("c_polygon_gml::WKTString");
vector<Geometry *> polygons;
vector<Geometry *> holes;
int i,j,k;
string resStr = "";

try{
GeometryFactory *gf=new GeometryFactory(new PrecisionModel(),0);

// for each outer ring create a CoordinateList and add all the points to it
for(i=0; i< static_cast<int>(ptPolygons.size()); i++) {
CoordinateList *cl1=CoordinateListFactory::internalFactory->createCoordinateList();
boundaryList bl = ptPolygons[i];
boundary b = bl[0];
TRACE_OUTPUT("Polygon " << i);
for(k=0; k< static_cast<int>(b.size()); k++) {
TRACE_OUTPUT("Added point " << b[k].x << ',' << b[k].y);
}

// for each hole create a coordinate list like above, create a polygon and add to a Geometry vector
for(j=1; j< static_cast<int>(bl.size()); j++) {
TRACE_OUTPUT("Hole " << j);
boundary b = bl[j];
CoordinateList *cl2=CoordinateListFactory::internalFactory->createCoordinateList();
for(k=0; k< static_cast<int>(b.size()); k++) {
TRACE_OUTPUT("Added point " << b[k].x << ',' << b[k].y);
}
TRACE_OUTPUT("Creating polygon for hole " << j << ": " << cl2->toString());
Geometry *geom1=gf->createPolygon(gf->createLinearRing(cl2),NULL);
TRACE_OUTPUT("Geometry " << j << " : " << geom1->toString());
holes.push_back(geom1);
delete cl2;
}
// create a polygon from the 1st CoordinateList and the holes
TRACE_OUTPUT("Creating polygon " << i << ": " << cl1->toString());
Geometry *geom2=gf->createPolygon(gf->createLinearRing(cl1),&holes);
TRACE_OUTPUT("test ");
TRACE_OUTPUT("Geometry " << i << " : " << geom2->toString());

// save this polygon in another vector
TRACE_OUTPUT("Adding polygon " << i);
polygons.push_back(geom2);
delete cl1;
}
TRACE_OUTPUT("Creating multi-polygon");
// when all done create a MultiPolygon object
Geometry *geom3=gf->createMultiPolygon(&polygons);
TRACE_OUTPUT("Creating string");
resStr = geom3->toString();

//clean up
delete geom3;
delete gf;
}
catch (GEOSException *ge) {
errMsg = ge->toString();
}
return resStr;
}

XML read in by class and stored in ptPolygons:
<?xml version="1.0" encoding="UTF-8"?>
<GDSRequest>
<query>
<AreaQuery outputContent="public">
<queryArea>
<Polygon srsName="osgb:BNG">
<outerBoundaryIs>
<LinearRing>
<coordinates>
339252,1019302
339252,1029077
348752,1029077
346102,1019653
339252,1019302
</coordinates>
</LinearRing>
</outerBoundaryIs>
<innerBoundaryIs>
<LinearRing>
<coordinates>
340000,1020000
340000,1021000
341000,1021000
341000,1020000
340000,1020000
</coordinates>
</LinearRing>
</innerBoundaryIs>
</Polygon>
</queryArea>
</AreaQuery>
</query>
</GDSRequest>

Output:
TR: TRACE ENTRY:c_polygon_gml::WKTString line 168 file c_polygon_gml.cpp
TR:   Polygon 0
TR:   Added point 339252,1.0193e+06
TR:   Added point 339252,1.02908e+06
TR:   Added point 348752,1.02908e+06
TR:   Added point 346102,1.01965e+06
TR:   Added point 339252,1.0193e+06
TR:   Hole 1
TR:   Added point 340000,1.02e+06
TR:   Added point 340000,1.021e+06
TR:   Added point 341000,1.021e+06
TR:   Added point 341000,1.02e+06
TR:   Added point 340000,1.02e+06
TR:   Creating polygon for hole 1: (340000,1.02e+06,1.7e-308) (340000,1.021e+06,1.7e-308) (341000,1.021e+06,1.7e-308) (341000,1.02e+06,1.7e-308) (340000,1.02e+06,1.7e-308)
TR:   Geometry 1 : POLYGON ((340000.0000000000000000 1020000.0000000000000000, 340000.0000000000000000 1021000.0000000000000000, 341000.0000000000000000 1021000.0000000000000000, 341000.0000000000000000 1020000.0000000000000000, 340000.0000000000000000 1020000.0000000000000000))
TR:   Creating polygon 0: (339252,1.0193e+06,1.7e-308) (339252,1.02908e+06,1.7e-308) (348752,1.02908e+06,1.7e-308) (346102,1.01965e+06,1.7e-308) (339252,1.0193e+06,1.7e-308)
TR:   test
Segmentation fault

Output when the hole is removed:
TR: TRACE ENTRY:c_polygon_gml::WKTString line 168 file c_polygon_gml.cpp
TR:   Polygon 0
TR:   Added point 339252,1.0193e+06
TR:   Added point 339252,1.02908e+06
TR:   Added point 348752,1.02908e+06
TR:   Added point 346102,1.01965e+06
TR:   Added point 339252,1.0193e+06
TR:   Creating polygon 0: (339252,1.0193e+06,1.7e-308) (339252,1.02908e+06,1.7e-308) (348752,1.02908e+06,1.7e-308) (346102,1.01965e+06,1.7e-308) (339252,1.0193e+06,1.7e-308)
TR:   test
TR:   Geometry 0 : POLYGON ((339252.0000000000000000 1019302.0000000000000000, 339252.0000000000000000 1029077.0000000000000000, 348752.0000000000000000 1029077.0000000000000000, 346102.0000000000000000 1019653.0000000000000000, 339252.0000000000000000 1019302.0000000000000000))
TR:   Adding polygon 0
TR:   Creating multi-polygon
TR:   Creating string
TR: TRACE EXIT:c_polygon_gml::WKTString
ERROR:
WTF format
MULTIPOLYGON (((339252.0000000000000000 1019302.0000000000000000, 339252.0000000000000000 1029077.0000000000000000, 348752.0000000000000000 1029077.0000000000000000, 346102.0000000000000000 1019653.0000000000000000, 339252.0000000000000000 1019302.0000000000000000)))

-----Original Message-----
From: strk [mailto:strk at keybit.net]
Sent: 28 June 2004 11:01
To: GEOS Development List
Subject: Re: [geos-devel] Problems creating polygons with holes

Can you send the test code ?
There are currently no known bug ...
--strk;

On Mon, Jun 28, 2004 at 10:15:45AM +0100, Darren Carman wrote:
> Hi all,
>
> I am creating polygons with holes and want to use geos to allow me to output them in WKT.
>
> A polygon without a hole works fine, but as soon as I add a hole I get a segmentation fault after calling the createPolygon function (GeometryFactory) and trying to run toString on that polygon.
>
> I am using version 1.0.
>
> I have tried getting the latest version from CVS but this causes a segmentation fault to occur while adding the 5th polygon coordinate to the CoordinateList (there are only 4 coordinates in the test polygon, the 5th being the first one repeated - I tried making it 6 to see if it was a problem with closing the polygon but I still got a segmentation fault while adding the 5th).
>
> Is there a fix for this, or has anyone come accross it?
>
> Thanks in advance,
> Darren
>
>
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```