[Paraview] Ghost cells for standalone Paraview

Moreland, Kenneth kmorel at sandia.gov
Wed Dec 3 15:47:49 EST 2008

OK, I understand now.  What you are asking for is not exactly what VTK/ParaView considers ghost cells.  You want add a layer of points around the boundary of an image data (i.e. 3D uniform regular grid) with minimum values to force the contour filter to create closed surfaces.  I don't know of an easy way to do this in ParaView (someone please correct me if I am wrong).

I think you can get the effect you want by using the clip by scalars feature.  Instead of using the contour filter, use the clip filter.  Change the "Clip Type" to "Scalar" and set the value to the isosurface you want to see.  The advantage of this approach is that the data you see will show the surface right at the edge of the volume instead of the arbitrary rounding at the edges you see in the Amira screenshots.  The disadvantage is that the underlying data is a solid unstructured geometry which could take up much more memory than the original image data.  If memory is an issue, let me know and I can describe memory-light version that uses a combination of the contour, extract surface, and clip filters.


On 12/3/08 1:16 AM, "Fabian Wein" <fabian.wein at lse.e-technik.uni-erlangen.de> wrote:

Hi Ken,

> > If you are not running in parallel, you do not need ghost cells.  If
> > necessary, just run the Clean to Grid filter to restore connectivity.
> > -Ken
> >     To close my isosurfaces of my unstructured grid I need ghost cells.
> >     I found that D3 is capable of doing this but I use a standalone
> >     ParaView.
> >
> >     What can I do? Shall I write a python filter?

I could not figure out how the Clean to Grid filter can help me. The
problem is, that my isosurfaces don't close. In my master thesis
I used Amira for visualization of cell data but had ghost cells. There
the surface is closed.

I add screenshots of what I get from ParaView and what I desire. Thanks
a lot for help - this was one of the reasons for me to move from gmv.


   ****      Kenneth Moreland
    ***      Sandia National Laboratories
*** *** ***  email: kmorel at sandia.gov
**  ***  **  phone: (505) 844-8919
    ***      web:   http://www.cs.unm.edu/~kmorel

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