Hi, I'm using GDALPolygonize to polygonize a dataset with one band created using MEM driver:
memdataset = GDALCreate(GDALGetDriverByName("MEM"),"", width, height, 0, GDT_Byte, NULL); GDALAddBand(memdataset, nPixelType, apszOptions); // in apszOptions[0] there are the band data Then, I create a MEM datasource, to store the polygons. Using MEM driver for OGR: memdatasource = OGR_Dr_CreateDataSource(OGRGetDriverByName("Memory"), "", NULL); Of course, I create a Layer to store the pols: hLayer = OGR_DS_CreateLayer(memdatasource, "Polygonized layer", NULL, wkbPolygon, NULL); As I can read in the source code of GDALPolygonize function (http://trac.osgeo.org/gdal/browser/trunk/gdal/alg/polygonize.cpp), a new Feature is created, based on the Feature Definition of the layer. hFeat = OGR_F_Create( OGR_L_GetLayerDefn( hOutLayer ) ); Then, the field of the Feature with index "iPixValue" is set with a pixel value (the pixel value of all the raster cells with the same value, polygonized in the same geometry, really) if( iPixValField >= 0 ) OGR_F_SetFieldInteger( hFeat, iPixValField, poRPoly->nPolyValue ); //poRPoly->nPolyValue is the pixel value The problem is that the MEM-based layer doesn't have fields. So, if I use "0" as iPixValField, I get an error, because there's no field with index 0 in the Feature. Of course, the same result if I use any value > 0. I thought the solution was to "modify" the Layer's Feature Definition to allow fields in the Features created. So, I created a new Feature Defintion, with a Field Definition of one field, of type OFTReal. Then, I created a new Feature following this schema, and I added this Feature to the Layer. I know, it's not the best way, and it didn't work. But I don't know how to "force" the MEM-based layer to allow fields in its features. Is it possible? If not, how could I polygonize a mem-based raster? Thanks in advance, and best regards, Jorge _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev