[gdal-dev] Writing raster - 0 in every even column

[Goo Creations]

Thanks, GDALCopyWords was what I was looking for

Thanks

Chris

On Fri, Jun 3, 2011 at 12:39 PM, Even Rouault
<even.rouault at mines-paris.org>wrote:

> Le vendredi 03 juin 2011 12:32:16, Goo Creations a écrit :
> > Ah, thanks. This solved the problem.
> > I however face the problem that I don't know which data type the image
> has.
> > So I can't hardcode the array to unsigned short, since it might sometimes
> > be a int32 or even a float. So is there a way to do this in a generic
> way?
>
> I'm not sure what you are trying to do exactly. There are various
> possibilities. Use good all switch() case() to care for different data
> types,
> which can be combined with using C++ templates to write generic code to
> reduce
> the amount of copying&pasting, use GDALCopyWords() to convert an array from
> one type to another one...
>
> >
> > Chris
> >
> > On Fri, Jun 3, 2011 at 12:21 PM, Even Rouault
> >
> > <even.rouault at mines-paris.org>wrote:
> > > Le vendredi 03 juin 2011 12:13:41, Goo Creations a écrit :
> > > > Hi all
> > > >
> > > > I have a strange problem when writing to a GDAL dataset. I'm
> currently
> > > > doing the following:
> > > >
> > > > *GDALDataset *mInputDataset = (GDALDataset*) GDALOpen("in.tif",
> > > > GA_ReadOnly);
> > > > GDALDataType type =
> > > > mInputDataset->GetRasterBand(1)->GetRasterDataType(); int mWidth =
> > > > mInputDataset->GetRasterXSize();
> > > > int mHeight = mInputDataset->GetRasterYSize();
> > > >
> > > > GDALDataset *mOutputDataset =
> > >
> > > mInputDataset->GetDriver()->Create("out.tif",
> > >
> > > > mWidth, mHeight, mBands, type, 0);
> > > >
> > > > int *data = <<get data for entire band>>
> > > > mOutputDataset->GetRasterBand(1)->RasterIO(GF_Write, 0, 0,
> > >
> > > aligner.width(),
> > >
> > > > aligner.height(), data, aligner.width(), aligner.height(), type, 0,
> 0);
> > > > mOutputDataset->FlushCache();
> > > > *
> > > >
> > > > The input image provided has a datatype of UINT16. When I hardcode
> all
> > > > "type" variables in the above example to GDT_Int32, then the image is
> > > > correctly created, but when I leave the example as is (hence with
> > > > GDT_UInt16 assigned to "type"), then I get a strange problem that
> every
> > > > second column has a value of 0. So every odd column has the correct
> > >
> > > values
> > >
> > > > in, but every even column has values of 0. I've checked the data
> array,
> > > > and all the values in there are correct.
> > > >
> > > > Does anyone know why this is happening?
> > >
> > > Yes, the type parameter must be consistent with the C type of the data
> > > array,
> > > otherwise weird things can happen, including crashes.
> > >
> > > In your exemple data is of type int*, so type must be set to GDT_Int32.
> > > If you want to write GDT_UInt16, then data must be declared as being of
> > > type
> > > unsigned short*
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20110603/b83c61b1/attachment.html