[vtkusers] Newbie question about vtkMeshQuality

Andriy Fedorov fedorov at bwh.harvard.edu
Wed Apr 27 13:04:20 EDT 2005 

Ok, I figured that out. What is wrong is that the vtkMeshQuality is 
different in CVS and in the latest official release (4.2). I didn't know 
that. Here's the header file from the official release:

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkMeshQuality.h,v $
  Language:  C++
  Date:      $Date: 2002/10/22 16:02:39 $
  Version:   $Revision: 1.3 $

  Copyright (c) 1993-2002 Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkMeshQuality - calculate quality of tetrahedral meshes
// .SECTION Description
// vtkMeshQuality will calculate the normalized quality ratio of the cells
// in a tetrahedral mesh according to the equation:
// <p> ratio = (radius of circumscribed sphere)/(radius of inscribed 
sphere)/3.
// <p> The minumum (and ideal) quality ratio is 1.0 for regular tetrahedra,
// i.e. all sides of equal length.  Larger values indicate poorer mesh
// quality.  The resulting quality values (and the tetrahedron volumes)
// are set as the Scalars of the FieldData of the output.

// .SECTION Thanks
// This class was developed by Leila Baghdadi, Hanif Ladak, and
// David Steinman at the Imaging Research Labs, Robarts Research Institute.

#ifndef __vtkMeshQuality_h
#define __vtkMeshQuality_h

#include "vtkDataSetToDataObjectFilter.h"

class VTK_GRAPHICS_EXPORT vtkMeshQuality : public 
vtkDataSetToDataObjectFilter
{
public:
  static vtkMeshQuality *New();
  vtkTypeRevisionMacro(vtkMeshQuality,vtkDataSetToDataObjectFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Turn on/off the calculation of volume for each cell (Default: On).
  // The volume the first component of the cell scalars in the output
  // data.
  vtkSetMacro(Volume,int);
  vtkGetMacro(Volume,int);
  vtkBooleanMacro(Volume,int);

  // Description:
  // Turn on/off the calculation of the quality ratio for each cell
  // (Default: On).  The ratio is 1 for a regular tetrahedron and
  // greater than one for other tetrahedrons.  The values are stored
  // in the second component of the cell scalars in the output data,
  // unless Volume calculation is off in which case the values are
  // stored in the first scalar component.
  vtkSetMacro(Ratio,int);
  vtkGetMacro(Ratio,int);
  vtkBooleanMacro(Ratio,int);


protected:
  vtkMeshQuality();
  ~vtkMeshQuality();
  void Execute();

  int Volume;
  int Ratio;


private:
  vtkMeshQuality(const vtkMeshQuality&);  // Not implemented.
  void operator=(const vtkMeshQuality&);  // Not implemented.

};

#endif




Mathieu Malaterre wrote:

> What is wrong with :
>
> $ ctest -R MeshQuality -V
>
> Test project
> Changing directory into 
> /home/mathieu/Dashboards/MyTests/VTK-gcc/Graphics/Testing/Cxx
>   1/  1 Testing MeshQuality
> Test command: 
> /home/mathieu/Dashboards/MyTests/VTK-gcc/bin/GraphicsCxxTests 
> MeshQuality -D /home/mathieu/Dashboards/MyTests/VTKData -T 
> /home/mathieu/Dashboards/MyTests/VTK-gcc/Testing/Temporary -V 
> Baseline/Graphics/MeshQuality.png
>
> Triangle quality of mesh
> /home/mathieu/Dashboards/MyTests/VTKData/Data/uGridEx.vtk
>  Edge Ratio:
>   range: 1.41421  -  1.41421
>   average: 1.41421  , standard deviation: 1.30634e-08
>  Aspect Ratio:
>   range: 1.39385  -  1.39385
>   average: 1.39385  , standard deviation: 8.87815e-09
>  Radius Ratio:
>   range: 1.20711  -  1.20711
>   average: 1.20711  , standard deviation: 1.83331e-09
>  Frobenius Norm:
>   range: 1.1547  -  1.1547
>   average: 1.1547  , standard deviation: 3.4377e-09
>  Minimal Angle:
>   range: 45  -  45
>   average: 45  , standard deviation: 2.92002e-07
>
> Quadrilatedral quality of mesh
> /home/mathieu/Dashboards/MyTests/VTKData/Data/uGridEx.vtk
>  Edge Ratio:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>  Aspect Ratio:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>  Radius Ratio:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>  Average Frobenius Norm:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>  Maximal Frobenius Norm:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>  Minimal Angle:
>   range: 90  -  90
>   average: 90  , standard deviation: 0
>
> Tetrahedral quality of mesh
> /home/mathieu/Dashboards/MyTests/VTKData/Data/uGridEx.vtk
>  Edge Ratio:
>   range: 1.41421  -  1.73205
>   average: 1.57313  , standard deviation: 0.158919
>  Aspect Ratio:
>   range: 1.36603  -  1.70711
>   average: 1.53657  , standard deviation: 0.170541
>  Radius Ratio:
>   range: 1.36603  -  1.39385
>   average: 1.37994  , standard deviation: 0.0139107
>  Frobenius Norm:
>   range: 1.19055  -  1.32283
>   average: 1.25669  , standard deviation: 0.0661417
>  Minimal Dihedral Angle:
>   range: 45  -  54.7356
>   average: 49.8678  , standard deviation: 4.86781
>
> Hexahedral quality of mesh
> /home/mathieu/Dashboards/MyTests/VTKData/Data/uGridEx.vtk
>  Edge Ratio:
>   range: 1  -  1
>   average: 1  , standard deviation: 0
>
> -- Process completed
>    Passed
>
> The following tests passed:
>         MeshQuality
>
> 100% tests passed, 0 tests failed out of 1
>
>
> This is tested every night...
> Mathieu
>
> Andriy Fedorov wrote:
>
>> Mathieu,
>>
>> Are you aware that the test you pointed me to is outdated: 
>> apparently, the functionality provided by vtkMeshQuality in the 
>> latest release of VTK is significantly restricted.
>>
>> AF
>>
>>
>> Mathieu Malaterre wrote:
>>
>>> Andriy,
>>>
>>>     Use the documentation of VTK. For example go to the doxygen of 
>>> the class you wish to use:
>>>
>>> http://www.vtk.org/doc/nightly/html/classvtkMeshQuality.html
>>>
>>>     Then scroll, you'll find a 'Tests' section, which will lead you to:
>>>
>>> http://www.vtk.org/doc/nightly/html/c2_vtk_t_8.html#c2_vtk_t_vtkMeshQuality 
>>>
>>>
>>>     In this case the choice is easy since there is only one test 
>>> written in c++:
>>>
>>> http://public.kitware.com/cgi-bin/viewcvs.cgi/*checkout*/Graphics/Testing/Cxx/MeshQuality.cxx?root=VTK&content-type=text/plain 
>>>
>>>
>>> This gives you an example on how to use this class:
>>>
>>> <snip>
>>>   vtkUnstructuredGridReader* mr = vtkUnstructuredGridReader::New();
>>>   vtkUnstructuredGrid* ug;
>>>   vtkMeshQuality* iq = vtkMeshQuality::New();
>>>
>>>   mr->SetFileName( fname );
>>>   mr->Update();
>>>
>>>   ug = mr->GetOutput();    // <-- this is the line you need
>>>   iq->SetInput( ug );
>>> </snip>
>>>
>>>
>>> HTH
>>> Mathieu
>>>
>>> Andriy Fedorov wrote:
>>>
>>>> I know this is something very simple... I am trying to use 
>>>> itkMeshQuality with a tetrahedral 3D mesh. Here's the code:
>>>>
>>>> #include "vtkUnstructuredGrid.h"
>>>> #include "vtkUnstructuredGridReader.h"
>>>> #include "vtkMeshQuality.h"
>>>> #include "vtkDataSet.h"
>>>> #include <iostream>
>>>>
>>>> int main(int argc, char **argv){
>>>>  if(argc<2)
>>>>    return -1;
>>>>
>>>>  vtkUnstructuredGridReader *vtk_mesh_reader =
>>>>    vtkUnstructuredGridReader::New();
>>>>  vtkMeshQuality *mesh_qual = vtkMeshQuality::New();
>>>>  vtkDataObject *output_mesh;
>>>>
>>>>  vtk_mesh_reader->SetFileName(argv[1]);
>>>>  vtk_mesh_reader->Update();
>>>>  vtkDataSet *input_mesh = vtkDataSet::SafeDownCast(
>>>>    vtk_mesh_reader);
>>>>  mesh_qual->SetInput(input_mesh);
>>>>  mesh_qual->Update();
>>>>  output_mesh = mesh_qual->GetOutput();
>>>>
>>>>  return 0;
>>>> }
>>>>
>>>> When I run it, I have failure here:
>>>>
>>>> ERROR: In 
>>>> /home/fedorov/SPL/slicer2/Lib/linux-x86/VTK/Common/vtkSource.cxx, 
>>>> line 384
>>>> vtkMeshQuality (0x8069318): Required input 0 is not assigned. 
>>>> Skipping execution.
>>>>
>>>> I realize it shuld be possible to figure out from the code, but I 
>>>> already spent couple of hours w/o success (my VTK experience 
>>>> approaches 0).  Can somebody give me a quick hint what I am 
>>>> missing? Thanks a lot!
>>>>
>>>> Andriy Fedorov
>>>> _______________________________________________
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>>>>
>>>
>>
>>
>

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