MantisBT - VTK
You'll see from the #if/#endif blocks that there's two possible ways to do it. The first is with a vtkArrayCalculator, where I set a very trivial function to simply copy out the one value. The other way is with a vtkImageExtractComponents. When doing it with the vtkArrayCalculator, the filter seems to work just fine but then the FFT yields values like :
p Array [0]: vtkDoubleArray "result", 2,097,152 points, 8 bytes per point
p Magnitude Range: 0.0000 1482912.5793
p Component 0 Range: -1048575.9848 1048575.8760
p Component 1 Range: -1048572.9243 1048579.0968
With a simple sin wave, the result should be almost purely imaginary, so the Component 0 range should be almost 0 to 0.
When I switch to using the vtkImageExtractComponents, the results look better:
p Array [0]: vtkDoubleArray "image", 2,097,152 points, 8 bytes per point
p Magnitude Range: 0.0000 1048576.0091
p Component 0 Range: -0.0557 0.0011
p Component 1 Range: -1048576.0089 1048576.0091
Unfortunately, when working with the vtkImageExtractComponents filter, I lose the other two fields if I had planned on using them for coloring or something. Also, my results aren't quite what I expected. Much better, but on more complex datasets I seem to get results that are a little off from the expected result. I don't know if the cause of all this is related, but I'm chasing down what I can.
So, any ideas?
stat.h (7,396) 1969-12-31 19:00https://www.vtk.org/Bug/file/5374/stat.h
fft.cxx (2,659) 1969-12-31 19:00https://www.vtk.org/Bug/file/5375/fft.cxx