[Paraview] Extracting boundary regions

[Renato N. Elias]

I had already tried that with no luck. The filter name suggested me 
exactly what I'm looking for. I also tried several possibilities using 
this filter, changed the normals, origin, turned the check box on and 
off, etc..., but the resulting selections were not what I was expecting. 
It should be simple to select points and cells by coordinates, shouldn't 
it? Maybe, it should be available from the "selection inspector" toolbar.

Renato.

Berk Geveci wrote:
> Hmm. I think you can do this in paraview 3. I added a filter call
> "Extract Cells by Region". It is like clip but it does not actually
> clip the cells it intersects, it either keeps them or discards them
> (user option). That filter would allow you to create a plane that
> intersects the cells to be included.
>
> -berk
>
> On Wed, Apr 9, 2008 at 3:02 PM, Renato N. Elias <rnelias at nacad.ufrj.br> wrote:
>   
>>  What a shame, I had forgotten the clip filter... but I'm afraid that the
>> clip box (or 6 planes) will not be accurate to select the right region since
>> it would try to intersect the mesh and not select the nodes and cells based
>> on their coordinates (as I did with the threshold). For example: with the
>> clip filter I could not select those nodes lying on the bottom and top faces
>> since they are shared by the cylinder and the clip filter would cut them
>> out.
>>
>>  Anyway, the clip filter can help to solve the problem partially.
>>
>>  Renato.
>>
>>
>>
>>  Berk Geveci wrote:
>>
>>     
>>> Wouldn't extract surface -> clip work? You may need 6 clip filters
>>> now. We are going to add the functionality of clipping with a box back
>>> in soon. You also be able to use the selection stuff. Select the cells
>>> and extract them maybe?
>>>
>>> -berk
>>>
>>>
>>> On Wed, Apr 9, 2008 at 12:09 PM, Renato N. Elias <rnelias at nacad.ufrj.br>
>>>       
>> wrote:
>>     
>>>       
>>>>  I'm looking for a way to extract boundary regions from solid
>>>>         
>> unstructured
>>     
>>>> meshes (tetrahedra). The purpose of this is simple: use ParaView to set
>>>> boundary conditions for a CFD code. In PV 2.6.2 I'm able to extract
>>>>         
>> plane
>>     
>>>> aligned regions using the following pipeline: (as an example, let's
>>>>         
>> consider
>>     
>>>> I'm extracting those boundary nodes lying on the maximum X coordinate:)
>>>>
>>>>  Unstructured mesh (tetrahedra) --> Extract surface --> Calculator (get
>>>> coords_0 scalar per point values) --> Threshould (Scalars = Result of
>>>>         
>> the
>>     
>>>> calculator filter, Lower and Upper set to the maximum value).
>>>>
>>>>  Ok, it works just fine. My problem is regarding non aligned boundaries.
>>>> Here is an example of what I'm trying to do
>>>> http://www.nacad.ufrj.br/~rnelias/paraview/regions.jpg . In this
>>>>         
>> example, I
>>     
>>>> can extract the plane boundary regions but I can't extract the cylinder
>>>>         
>> at
>>     
>>>> the middle of the domain. Any idea?
>>>>
>>>>  Regards
>>>>
>>>>  Renato.
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>>>>
>>>>
>>>>
>>>>         
>>>
>>>       
>>     
>
>