[Paraview] Contours of integer array

Mon Jul 11 08:44:41 EDT 2016

Hi David,

ah, ok. However, in this case I’m wondering what I am doing wrong here: If I use the Extract Region Surface filter, my dataset looks just like before. Do I need to create an array with a certain name that contains the information on which the regions are extracted? And does this work also for 2D (unstructured grid with vtkQuads) or only in 3D?

Sorry for being so slow :-/

Michael

On 11 Jul 2016, at 14:29 , David E DeMarle <dave.demarle at kitware.com<mailto:dave.demarle at kitware.com>> wrote:

Extract region surface will do all domains at the same time.

What it does is iterate over all cells and extract the faces of the cell for which either their is no neighbor or the neighbor cell has different material.

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909

On Mon, Jul 11, 2016 at 8:25 AM, Schlottke-Lakemper, Michael <m.schlottke-lakemper at aia.rwth-aachen.de<mailto:m.schlottke-lakemper at aia.rwth-aachen.de>> wrote:
Hi David,

Thanks for your answer. From what I understand, your suggestions allow me to extract the surface for a single domain. However, what I am really looking for is something like in the second example, i.e., where I get lines representing the domain boundaries between *all* domains at once. I just want them to align neatly with the actual boundaries and not have them diluted by the Cell-to-Point filter. Any idea how I can achieve that? Or maybe I just misunderstood you…

Michael

On 11 Jul 2016, at 13:37 , David E DeMarle <dave.demarle at kitware.com<mailto:dave.demarle at kitware.com>> wrote:

Could try threshold, or nearly equivalently clip by scalar, followed by surface filter.

Another option is the material interface filter. That requires unstructured grid input and an integer or idtype material array. Clip its output or use opacity to see inside since its external surface looks the same as its input's.

On Jul 11, 2016 6:41 AM, "Schlottke-Lakemper, Michael" <m.schlottke-lakemper at aia.rwth-aachen.de<mailto:m.schlottke-lakemper at aia.rwth-aachen.de>> wrote:
Maybe some visualization might help to illustrate the problem. This is what the domain decomposition looks like for two domains:

<PastedGraphic-1.png>

There are only two domains with values 0 and 1, respectively. I then select & apply the “Cell Data to Point Data” filter, then the “Contour” filter with only one isosurface set to “0.5”. However, in this example, the result is a blank screen, i.e., no visible output from the Contour filter.

In another example, I get the following result:
<PastedGraphic-2.png>

The sharp, colored interfaces of the integer array in the back is clearly visible. In this case, there are 5 domains (values [0,4]) and I used 0.5, …, 3.5 as the isosurface values in the contour filter. While in this case I actually get an output (white lines), they follow the fuzzy output of “Cell Data to Point Data” and I am not able to reconstruct the sharp interfaces.

To conclude, my problems are actually twofold: I would like to find out how to restore sharp contours, and - if that does not work - at least how to make this approach work for all datasets I am looking at.

Again, thanks a lot in advance, and please excuse my double posting...

Michael

On 11 Jul 2016, at 12:16 , Schlottke-Lakemper, Michael <m.schlottke-lakemper at aia.rwth-aachen.de<mailto:m.schlottke-lakemper at aia.rwth-aachen.de>> wrote:

Hi folks,

I would like to visualize an integer array of an unstructured dataset based on voxels, which contains MPI rank ids generated by a filter we use. To achieve this, I plan to somehow extract the “sharp” interfaces, similar to what the contour filter does, to obtain a visual representation of the domain decomposition. However, for the contour filter, I first have to call “Cell data to point data”, which smears out the previously sharp interfaces and causes connectivity problems of the resulting contours, as in some areas the domain decomposition features are very small.

Is there another way how I could extract these contours? Please note that I am not using vtkProcessId but rather an own integer array.

Thanks a lot in advance

Michael

--
Michael Schlottke-Lakemper

Institute of Aerodynamics and Chair of Fluid Mechanics
RWTH Aachen University
Wüllnerstraße 5a
52062 Aachen
Germany

Phone: +49 (241) 80 95188<tel:%2B49%20%28241%29%2080%2095188>
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Web: http://www.aia.rwth-aachen.de<http://www.aia.rwth-aachen.de/>

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