[vtkusers] need help on vtkImageFFT please

[Cory Quammen]

Stefan,

It looks like  you are setting the wrong dimensionality in the
vtkImageFFT class. You have a 2D image of dimension 3x3, so the
vtkImageFFT class should have dimensionality 2.

Hope that helps,
Cory

On Tue, Apr 15, 2008 at 4:39 AM, Stefan  Huber <Huber.Ste at gmx.at> wrote:
> Hi at all,
>
>  Can somebaody help me with vtkImageFFT?
>  I have an ImageDataObject like this:
>    vtkImageData * img = vtkImageData::New()
>    img->SetDimension(3,3,1);
>    img->SetScalarTypeToFloat();
>    img->AllocateScalar();
>
>    float * ptr = (float *) img->GetScalarPointer();
>    for  (int i = 0; i < 3; i++){
>       for (int j = 0; j < 3; j++){
>          *ptr++ = 1;
>       }
>    }
>
>  when i make some Queries on this Dataobject i get the information about the size and extent.
>    Extent is 0 2 0 2 0 0
>    NumberofComponent = 1
>    Size of Scalar = 9
>
>  Now i want to make a FFT of this image. But the result of the FFT is very strange and isn't correct. I don't know whats wrong. Please help me.
>  The code for my FFT is this.
>    vtkImageFFT *fft = vtkImageFFT::New();
>    fft->SetDimensionality(1);
>    fft->SetInput(img);
>    fft->Update();
>
>    to print result of FFT:
>    for (i = 0; i < fft->getOutput()->GetNumberofPoints(); i++)
>      im->fft->GetOutput()->GetPointData->GetScalars()->GetComponent(id,1);
>      re->fft->GetOutput()->GetPointData->GetScalars()->GetComponent(id,0);
>      cout << .....
>      id ++;
>   }
>
>  Do you know whats wrong?
>  Thanks Stefan
>
>
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-- 
Cory Quammen
Department of Computer Science
University of North Carolina at Chapel Hill
http://www.cs.unc.edu/~cquammen