[gdal-dev] [ogr] Unexplained third dimension in linear ring

[Alex Hagen-Zanker]

> The problem seems to be that adding a 2D OGRPoint  to a 2D 
> OGRLinearRing results in a 3D OGRLinearRing.

Sorry to bother you with this, I found it myself.
It is the following function in ogrlinestring.cpp that looks like a bug 
to me:

void OGRLineString::setPoint( int iPoint, double xIn, double yIn, double 
zIn )

{
     if( getCoordinateDimension() == 2 )
         Make3D();

     if( iPoint >= nPointCount )
         setNumPoints( iPoint+1 );

     paoPoints[iPoint].x = xIn;
     paoPoints[iPoint].y = yIn;

     if( zIn != 0.0 )
     {
         Make3D();
         padfZ[iPoint] = zIn;
     }
     else if( getCoordinateDimension() == 3 )
     {
         padfZ[iPoint] = 0.0;
     }
}

How about changing it to this:

void OGRLineString::setPoint( int iPoint, double xIn, double yIn, double 
zIn )

{
     if( iPoint >= nPointCount )
         setNumPoints( iPoint+1 );

     paoPoints[iPoint].x = xIn;
     paoPoints[iPoint].y = yIn;

     if( zIn != 0.0 &&  getCoordinateDimension() < 3 )
         Make3D();

     if( getCoordinateDimension() == 3 )
         padfZ[iPoint] = zln;
}