[Paraview] paraview plugin for vtkImageGaussianSmooth, uniform grid slice representation smoothness

[Burlen Loring]

Hi Kate,

Does changing from Slice representation to Surface representation make a 
difference? does your dataset have cell or point data?

Burlen

On 03/14/2012 01:27 PM, FISSELL at pitt.edu wrote:
> Hi Burlen,  Utkarsh,
>
> Thanks much for your detailed answers, and the caveat.
> A developer here just told me that vtkImageGaussianSmooth
> might not be what I need.  I am trying to achive a non-pixellated
> look in a rendering of a slice from a volume.
>
> Right now I read in the volume and choose a slice representation to
> look at a selected plane.  The datatype remains uniform grid.
> As per the image intensities in the voume, it looks a bit pixellated.
> Changing shading between flat/Gouraud makes no difference, I think
> because its not a surface.
>
> If I read in the volume and then use the slice filter to extract a slice.
> The output slice is polygonal mesh datatype.
> I choose a surface representation to look at that slice and there is
> a nice smoother look across the pixels.  (Changing shading between
> flat/Gouraud
> doesn't seem to make a  difference here either.)
>
> The developer here thinks that even if I pre-smooth my volume with
> vtkImageGaussianSmooth the uniform grid slice representation will
> look a little pixellated.  Is there a way to get the nice smoothness of
> the polygonal mesh surface look on my uniform grid slice representation ?
> My script will just be a little more complicated if I need to call the
> slice filter,
> so I'd rather not if this can be handled at the representation level.
>
> thanks
> kate
>
>
>> Hi Kate,
>>
>> It shouldn't be too hard for you to expose the vtkImageGaussianSmooth in
>> PV.  I have one caveat for you re: using vtkImageGaussianSmooth in
>> parallel: when it runs it will trigger a complete re-execution of your
>> entire pipeline including the reader.This happens because
>> vtkImageGaussianSmooth increases the update extents which, unless
>> something has changed in the recent version of PV, would be satisfied by
>> the reader re-executing. this could cause you some performance related
>> issues especially for large data where I/O becomes a significant
>> bottleneck. On the other hand, this re-execution would happen only when
>> running in parallel and if you have small data it might not be too bad.
>>
>> I encountered this issue a while back. with our data size the additional
>> I/O was unacceptable. i wrote a parallel ghost cell generator for image
>> data to prevent the pipeline re-execution for operations like kernel
>> convolution that require ghost cells. The plugin includes a kernel
>> convolution filter as well. To use it you'd have to build and load our
>> plugin and add the "image ghosts" filter right before the "kernel
>> convolution" filter. Our kernel convolution filter also has a CUDA
>> implementation that's about 20x faster than the cpu version (note: CUDA
>> stuff is still being developed, still some issue when update extent is
>> too large to fit on the gpu). I'm attaching a link to the latest release
>> of the plugin in case you could use it. It requires a parallel build of
>> PV. http://www.hpcvis.com/SciVisToolKit/SciVisToolKit-12.02.tar.gz
>>
>> Burlen
>>
>> On 03/14/2012 10:16 AM, FISSELL at pitt.edu wrote:
>>> Hi,
>>>
>>> I didn't see a paraview plugin for the  vtkImageGaussianSmooth.cxx
>>> filter
>>> in the paraview Filters menus or the filters.xml file.
>>> Is there some equivalent ?
>>>
>>> If not:  am I right that I will need to write a little paraview plugin
>>> wrapper in
>>> order to be able to use vtkImageGaussianSmooth in a pvpython script ?
>>> Any reason other than somewhat ugly parameter specification or lack
>>> of interest/time that there isn't a plugin ?
>>>
>>> thanks
>>> kate
>>>
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>>
>