[Paraview] Image Padding : extent problem again

[Jérôme]

Hi,
I am back with the strange extent/bounds problem (see other threads...)

I want to process FFT-based image convolution in ParaView. Thus I
enabled different VTK filters in ParaView so that I can implement the
following pipeline :

- Read an image and pad it to include
- built a kernel (eg. Wavelet source), normalize it to 1 and pad it in
order to match the image extent
- FFT image and kernel
- Multiply the two FFT
- R-FFT
- Crop

It *should* work ! An "Insight journal" paper has been proposed on
this topic. The first thing I had to do was to enable the VTK
ImagePadFilter's children (mirror, constant and wrap). You will find
the ServerManager XML attached. Problem is that..it doesn't work.

Please try this:
- First, load the XML through the "Manage Plugins" in the "Tools"
menu. It will add a "Image Padding (Constant)" to the filters menu.
- Create a wavelet source with default values
- Plug the "Image Padding (constant)" filter to the wavelet source and
set the OutputWholeExtent to [-20 20 -20 20 -20 20]

Press apply and set the wavelet source to "visible": the bounding
boxes seem to look good, isn't it? Thus, we expect the Pad filter
output extent to be [-20 20 ...].
Now, go to the information tab of the pad filter: extent is [-10
10...], the same as input!
Now, set the representation to slice: "Cannot volume render since no
point (or cell) data available."
Now, set the representation to volume: it works, but with input extent.

If you set the OutputWholeExtent to [-5 5 ... ], this bug doesn't
occur. It is an enlarging-exclusive extent weird behaviour. It means
that today, I am not able to:
   - resample images with finer resolution
   - build volume with input-independent extent
   - pad images
in ParaView.

Please, please, let me know if you can reproduce the problem. If so, I
will (re)submit a bug on Mantis.
Let me know also if this is a builtin limitation of ParaView (because
of Parallel Visualisation or something) and I will stop annoying you
with that.

Thanks a lot
Jerome
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