[vtkusers] how to use vtkMeshQuality..??

[John Platt]

Hi,

The threshold filter needs to know which data array to use for performing comparisons. SetInputArrayToProcess() says use the active cell scalars. This is the new cell array called "Quality". Your previous scalars are still there (assuming the filter passes them) but are no longer tagged as the active scalars.

HTH

John. 
  ----- Original Message ----- 
  From: Rakesh Patil 
  To: John Platt 
  Cc: David Doria ; vtkusers 
  Sent: Wednesday, February 24, 2010 11:14 AM
  Subject: Re: [vtkusers] how to use vtkMeshQuality..??



  Well,

  You have hit it right on the target.. :-) thanks... Clarify me one more thing.. 
  What is this vtkDataSetAttributes::SCALARS..?? Coz, my grid is already having one scalar set...

  Thanks


    ---------- Original message ----------
    From:"John Platt"< jcplatt at dsl.pipex.com >
    Date: 24 Feb 10 14:51:56
    Subject: Re: [vtkusers] how to use vtkMeshQuality..??
    To: "Rakesh Patil" , "David Doria" 

    Hi,

    The per-cell quality is added to the mesh's cell data in an array named 
    "Quality" and set as the active scalars.
    You can now use vtkThreshold to select only those cells which "fail" the 
    quality measure...

    selectCells = vtkThreshold::New();
    selectCells->ThresholdByLower( 20);
    selectCells->SetInputArrayToProcess( 0, 0, 0, 
    vtkDataObject::FIELD_ASSOCIATION_CELLS,
    vtkDataSetAttributes::SCALARS );

    HTH

    John.

    ----- Original Mes sage ----- 
    From: Rakesh Patil
    To: David Doria
    Cc: vtkusers
    Sent: Wednesday, February 24, 2010 4:53 AM
    Subject: Re: [vtkusers] how to use vtkMeshQuality..??





    Hi..

    I have gone through that example. And it is quite easy to follow. Anyways, 
    this is what i want to achieve:

    I have a Finite Elemental Mesh generated by one of the solver. Now, i want 
    to check the quality of mesh, cell wise.
    And if a particular cell doesn't satisfy the quality condition, then i have 
    to indicate that cell as unqualified cell.

    For example, suppose i impose a condition on min angle as 20. i.e. all the 
    cells in the mesh must have angles greater than or equal to 20. If it is 
    less than 20, then that particular cell must be displayed with say red color 
    or any other color.

    In vtkMeshQuality, I didnt find any function or method where i can set this 
    min angle value. I think, it has a default in built value set for m in angle. 
    I also found out that vtkMeshQuality makes use of VERDICT api.. But got no 
    clue how to put the condition on the minimum angle..

    Any idea how to get through this problem..??

    Tha nks

    Regards
    ---------- Original message ----------
    From:David Doria< daviddoria+vtk at gmail.com >
    Date: 23 Feb 10 19:18:28
    Subject: Re: [vtkusers] how to use vtkMeshQuality..??
    To: rakeshthp at in.com


    On Tue, Feb 23, 2010 at 7:05 AM, Rakesh Patil wrote:

    Hello,

    Can anyone explain me what exactly the vtkMeshQuality does.??

    According to me, it checks the quality of each and every cells.. Right.?? 
    but the output what am getting is very strange.

    If the number of cells in the grid is say 'n'. then the values, what i get 
    is first n/2 only, for rest n/2 cells, i get 0 values.

    What is the actual output of vtkMeshQuality??

    Thanks

    Regards
    Rakesh Patil




    Have you looked at this:
    http://www.vtk.org/Wiki/VTK/Examples/MeshQuality


    Let us know if it doesn't clear some things up.

    Thanks,


    David



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