[vtkusers] How to use vtkCellDerivatives with unstructured grid image

[Dominik Szczerba]

I never used the filter (in such cases I recommend custom filters) but
may be able to clarify some confusion about SetInputArrayToProcess. It
just explicitly tells the filter which array and of which type to take
in case there are multiple ones:

http://www.vtk.org/doc/nightly/html/classvtkAlgorithm.html#a6bea16e1329609dbccce0ff8d2367484

Typical use:

SetInputArrayToProcess(0,0,0,0,"PointScalar");
SetInputArrayToProcess(0,0,0,1,"CellMarker");

Good luck
Dominik


On Wed, Jun 15, 2011 at 8:25 PM, Seth Gilchrist <seth at mech.ubc.ca> wrote:
> Hello,
> Sorry to bump, but I'm still struggling with this and can't find any
> good help in my books or online.  I have the "VTK Users Guide" and
> "The Visualization Toolkit: An Object-Oriented Approach to 3-D
> Graphics," but neither of them is any help in this case.
>
> Can anybody help with this question?  Examples, hints, whatever you
> can do is really appreciated.
>
> Cheers,
> Seth
>
> Previous message:
> Hello,
> I have the unstructured grid image printed at end of this email, with two
> point data sets "Dispamcement" (vectors) and "Optimizer Value" (scalors).  I
> want to use vtkCellDerivatives to calculate the strain tensors from the
> "Displacement" point data.  I can't figure out how to input the data into
> vtkCellDerivatives.  I have tried:
>
> vtkCellDerivatives  *dCalc = vtkCellDerivatives::New();
> dCalc->
> SetTensorModeToComputeStrain();
> dCalc->SetInput( image->GetPointData()->GetArray("Displacement") );
> dCalc->Update();
>
> and
>
> vtkCellDerivatives  *dCalc = vtkCellDerivatives::New();
> dCalc->SetTensorModeToComputeStrain();
> dCalc->SetInput(image);
> dCalc->SetInputArrayToProcess( [uh...I get lost here, I've tried a lot of
> things]  );
> dCalc->Update();
>
> I either can't get it to compile, or the output of the filter is the same as
> the input.
>
> Can anybody point me in the right direction?
>
> Thanks,
> Seth
>
> The cells in the image are quadratic tets.
>
> image->Print( std::cout )...
>
> vtkUnstructuredGrid (0x10f1150)
>  Debug: Off
>  Modified Time: 268
>  Reference Count: 1
>  Registered Events: (none)
>  Source: (none)
>  Information: 0x10e6130
>  Data Released: False
>  Global Release Data: Off
>  UpdateTime: 269
>  Release Data: Off
>  UpdateExtent: Not Initialized
>  Update Number Of Pieces: 1
>  Update Piece: 0
>  Update Ghost Level: 0
>  MaximumNumberOfPieces: 1
>  RequestExactExtent: Off
>   Field Data:
>    Debug: Off
>    Modified Time: 252
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 0
>    Number Of Components: 0
>    Number Of Tuples: 0
>  Number Of Points: 81
>  Number Of Cells: 30
>  Cell Data:
>    Debug: Off
>    Modified Time: 259
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 0
>    Number Of Components: 0
>    Number Of Tuples: 0
>    Copy Tuple Flags: ( 1 1 1 1 1 0 1 )
>    Interpolate Flags: ( 1 1 1 1 1 0 0 )
>    Pass Through Flags: ( 1 1 1 1 1 1 1 )
>    Scalars: (none)
>    Vectors: (none)
>    Normals: (none)
>    TCoords: (none)
>    Tensors: (none)
>    GlobalIds: (none)
>    PedigreeIds: (none)
>  Point Data:
>    Debug: Off
>    Modified Time: 268
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 2
>    Array 0 name = Displacement
>    Array 1 name = Optimizer Value
>    Number Of Components: 4
>    Number Of Tuples: 81
>    Copy Tuple Flags: ( 1 1 1 1 1 0 1 )
>    Interpolate Flags: ( 1 1 1 1 1 0 0 )
>    Pass Through Flags: ( 1 1 1 1 1 1 1 )
>    Scalars: (none)
>    Vectors: (none)
>    Normals: (none)
>    TCoords: (none)
>    Tensors: (none)
>    GlobalIds: (none)
>    PedigreeIds: (none)
>  Bounds:
>    Xmin,Xmax: (57.5, 67.3)
>    Ymin,Ymax: (45.7, 56.7)
>    Zmin,Zmax: (41.7, 59.1)
>  Compute Time: 283
>  Number Of Points: 81
>  Point Coordinates: 0x10e7890
>  Locator: 0
>  Number Of Pieces: 1
>  Piece: 0
>  Ghost Level: 0
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