i guess it has to do with the way slice representation works? I'm sure
Utkarsh knows, and may know a way to make it do what you want.
I hadn't noticed this as our data has such a high resolution that the
differences between slice and surface representations aren't showing up.
but zooming in I can see what you mean.
Does the niftivolume reader let you subset the data? you could
effectively select a slice that way, which has the added benefit of
reducing your I/O, and use the surface representation to get the look
you desire.
On 03/14/2012 01:40 PM, [email protected] wrote:
Hi Burlen,
When I use 2nd method below, and extract a slice with slice filter, I do
use Surface representation and that is the look I am trying to achieve.
When I use 1st method below (which is what I am trying to stick with)
if I switch to Surface representation I get the surface over the entire 3D
volume, which is not what I want. I am effectively using the slice
representation
to select a slice for viewing.
I am reading in my 3D volume with the NiftiReader plugin (NIfTIVolumereader)
and I think it gives me point data.
thanks,
Kate
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, [email protected] 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, [email protected] 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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