Nathanael Inkson wrote:
Hi Ken,
“The mesh quality filter will be run multiple times on multiblock data
(once per block), but I assume that is not the case for you as volume
rendering is not available on data with more than one block.”
I think this sentence sums up my problem: the unstructured grid does
indeed consist of multiblock data.
Ok thanks so much for your help. I will look for a different approach
to what I am trying to do.
Keep the list informed as to what you find as more users are starting to
use very large meshes.
Stephen
Thanks for your time.
Nat.
*Best Regards*
* *
*Dr. Nathanael Inkson,***
* *
*Computational Fluid Dynamics Developer,***
*Digital Flow Solutions,***
****
******
**mob: + 44 7872010167******
**web: wirthresearch.com <http://wirthresearch.com>**
------------------------------------------------------------------------
*From:* Moreland, Kenneth [mailto:[EMAIL PROTECTED]
*Sent:* 02 September 2008 18:41
*To:* Nathanael Inkson
*Cc:* Simon Hubbard; [email protected]
*Subject:* RE: Strange behaviour with large datasets
I am a bit confused. The initial question sounded like a volume
rendering problem; you could not see the result of the mesh quality
filter very well. Is the problem you are reporting that the output of
the mesh quality filter is incorrect? Do the ranges look wrong in the
information tab? Does the threshold filter not extract cells you
expect to be of poor quality?
Does your modified mesh quality filter behave differently than the one
that comes with ParaView? The pipeline should not be updating your
filter unless it needs to refresh the calculation. The mesh quality
filter will be run multiple times on multiblock data (once per block),
but I assume that is not the case for you as volume rendering is not
available on data with more than one block. The cell count might be
off because you are running in parallel. Each process will have a
partition of the whole mesh, so the cell count will be smaller unless
you are getting the global multiprocess controller and adding up all
the cells.
If the pipeline is inappropriately calling your filter multiple times,
it might be that your filter is calling its own Modified method
(usually indirectly through, for example, a call to one of the Set*
macros). You can check for that by making sure that the MTime ivar
does not change while invoking RequestData or any other
ProcessRequests method.
-Ken
------------------------------------------------------------------------
*From:* Nathanael Inkson
[mailto:[EMAIL PROTECTED]
*Sent:* Tuesday, September 02, 2008 11:15 AM
*To:* Moreland, Kenneth
*Cc:* [EMAIL PROTECTED]
*Subject:* RE: Strange behaviour with large datasets
Dear Ken,
Thanks for your answer but I am not sure that this is the reason as I
have other fields which have large values. If I count the number of
cells in one pass through vtkMeshQuality and output to a file, I find
that the answer is far less than the actual number of cells in the
mesh. I have a gut feeling that because the mesh is so big that the
MeshQuality filter is entered several times as it updates the progress
bar, wouldn’t that mean that the newly created quality arrays are
overwritten each time the filter is entered? I’m not too sure about
how the filters actually work.
How is this prevented?
Thanks
Nat.
*Best Regards*
* *
*Dr. Nathanael Inkson,***
* *
*Computational Fluid Dynamics Developer,***
*Digital Flow Solutions,***
****
******
**mob: + 44 7872010167******
**web: wirthresearch.com <http://wirthresearch.com>**
------------------------------------------------------------------------
*From:* Moreland, Kenneth [mailto:[EMAIL PROTECTED]
*Sent:* 02 September 2008 14:58
*To:* Nathanael Inkson; [email protected]
*Subject:* RE: Strange behaviour with large datasets
If your mesh is typical, then probably most of the cells are of good
quality, and there are a handful of cells of bad quality. Thus, when
volume rendering most of the cells will be invisible and that handful
of cells will have some opacity.
The probable reason that you can see them in a small mesh and not a
large one is that the cells are spatially much smaller (with respect
to the entire mesh) for the large mesh. In correct volume rendering, a
material of a constant density will have smaller opacity the thinner
it gets. Your cells are probably so small that there is not enough
accumulation to actually see them.
You can adjust for the small scale of the cells by adjusting the
“Scale” parameter in the Color Scale Editor dialog box. That parameter
is actually a unit length specification for the opacity parameters
given. Setting it to about cell length divided by 10 should give you
decent results. However, an easier and probably more effective
approach would be to bag the volume rendering and use the threshold
filter to extract the cells of interest (in this case, the bad ones).
-Ken
------------------------------------------------------------------------
*From:* [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] *On Behalf Of *Nathanael Inkson
*Sent:* Tuesday, September 02, 2008 7:31 AM
*To:* [email protected]
*Subject:* [Paraview] Strange behaviour with large datasets
Dear Paraview people,
I am working with Paraview with very large datasets (around 40Gb). I
have written a filter derived from MeshQuality which doesn’t seem to
display the returned data arrays correctly. I checked with the same
mesh and the MeshQuality filter. The same thing happens: I put the
output on volume rendering to look at the quality field and the whole
dataset is invisible. I have tried rescaling the range but to know
avail. Is this a known problem?
Any advice? With smaller meshes the problem disappears and the quality
field is visible with volume rendering.
*Best Regards*
* *
*Dr. Nathanael Inkson,***
* *
*Computational Fluid Dynamics Developer,***
*Digital Flow Solutions,***
****
******
**mob: + 44 7872010167******
**web: wirthresearch.com**
------------------------------------------------------------------------
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