FFT

[Gavin Tabor]

Charles Law wrote:
> 
> The FFT and RFFT works fine.  As a sanity check I put together an example
> that does a correlation operation in the frequence
> domain.  vtk/imaging/TestFFTCorrelation.tcl

Thanks. That looks very useful (fairly close to what I am trying to
do).

I do have one further problem that I am experiencing trouble with - any
help would be appreciated. My data comes from a vtkProbeFilter with a
regular array of points. To feed into the FFT algorithm, I need to 
turn this into a vtkStructuredPoints object. How do I do this? I've
tried using CopyStructure(probe->GetOutput), but it only copies the
geometry, not the data.

Thanks for any help.

Gavin

> 
> The only difference in the result (compared to spatial vtkImageCorrelation)
> is results outside of the boundaries are wrapped to the other side of the
> image.  The price you pay for operations in Frequencey domain.
> 
> Charles.
> 
> At 02:46 PM 5/11/00 +0100, John Biddiscombe wrote:
> > >I am worried about what you say about the errors here.
> >
> >Well, I wanted to
> >
> >FFT(data)*Conjugate(FFT(other data))
> >and do a straightforward convolution. I failed to get vtk to do it in the
> >space of an hour or so and thought - it'd be quicker to do it myself using
> >other software. If you get it working, please keep me informed.
> >
> >ttfn
> >
> >John B
> >
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-- 

Dr. Gavin Tabor
School of Engineering and Computer Science
Department of Engineering
University of Exeter
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