[gdal-dev] Re: reg GDALPolygonize

[Srikanth]

Hi ,

I have found the solution myself.
Below is the piece of code for polygonizing the raster.

Yet there is another problem i am facing. I am unable to create a mask band
for a particular pixel value.I understand that could be done using
thresholding. But I did not find any method for that in GDAL.

Any help/suggestions are appreciated.


GDALAllRegister();

OGRRegisterAll();

String pszFilename = "C:\\Images\\s3dImages\\geo_liss.tif";

poDataset = (GDALDataset *) GDALOpen( pszFilename, GA_ReadOnly );

GDALRasterBand *poBandR,*poBandMask ;

poBandR = poDataset->GetRasterBand(1);

poBandR->CreateMaskBand(GMF_PER_DATASET);

poBandMask = poBandR->GetMaskBand() ;

poBandMask->Fill(10,0);

 const char *pszDriverName = "ESRI Shapefile";

OGRSFDriver *poDriver;

poDriver =
OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName(pszDriverName);

OGRDataSource* ds = poDriver->CreateDataSource("Shape", NULL );

OGRLayer* poLayer = ds->CreateLayer("myfile",NULL,wkbMultiPolygon,NULL);

CPLErr er = GDALPolygonize(poBandR , poBandMask , poLayer
,1,NULL,NULL,NULL);

 poLayer->SyncToDisk();

OGRDataSource::DestroyDataSource(ds);



On Mon, Nov 16, 2009 at 3:27 PM, Srikanth <srikanth1947 at gmail.com> wrote:

> Dear All ,
>
> I am trying to convert a raster to vector using GDALPolygonize function .
> Below is the code I am using
> GDALAllRegister();
>
> String pszFilename = "C:\\Images\\image.tiff";
>
> poDataset = (GDALDataset *) GDALOpen( pszFilename , GA_ReadOnly );
>
> GDALRasterBand *poBandR,*poBandG,*poBandB;
>
> poBandR = poDataset->GetRasterBand(1);
>
> OGRLayer* poLayer;
>
> GDALPolygonize(poBandR , NULL , poLayer ,1,NULL,NULL,NULL);
>
>
> The process is crashed in the polygonize function. I wonder what might be
> wrong with the above. (or should I assign memory to OGRLayer ?)
>
> Any suggestions/examples regarding the same are appreciated.
>
>
> --
> Regards,
> Srikanth K.
>
>
>


-- 
Regards,
Srikanth K.
www.servetheneedy.org
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