[vtkusers] Problem assigning vectors to vtkImageData

[Martijn Steenwijk]

And some advice for others who want to use this code. The order of the
iteration should be changed to k,j,i to let the indices of the array
correspond to the indices of the points J.

 

Best,

Martijn

 

 

Van: David E DeMarle [mailto:dave.demarle at kitware.com] 
Verzonden: zondag 22 januari 2012 14:23
Aan: martijnsteenwijk at gmail.com
CC: vtkusers at vtk.org
Onderwerp: Re: [vtkusers] Problem assigning vectors to vtkImageData

 

If reader executes after you assigned the vectors, the array will be
discarded. Try making a shallow copy of reader's output, add your array, and
visualize that instead.

On Jan 22, 2012 5:06 AM, "Martijn Steenwijk" <martijnsteenwijk at gmail.com>
wrote:

Dear all,

 

I would like to assign vectors to a vtkImageData which already contains
scalars which will be used for coloring. I'm using the code as below:

 

vtkImageData *im = reader->GetOutput();

vtkSmartPointer<vtkFloatArray> vec = 

       vtkSmartPointer<vtkFloatArray>::New();

vec->SetName("v1");

vec->SetNumberOfComponents(3);

 

for(int i = 0; i< im->GetDimensions()[0]; i++)

       {

              std::cout << i << std::endl;

              for(int j = 0; j< im->GetDimensions()[1]; j++)

              {

                     for(int k = 0; k< im->GetDimensions()[2]; k++)
// assign dummy vectors (1,1,1)

                     {

                           float tuple[3];

                           tuple[0] = (float)1.0;

                           tuple[1] = (float)1.0;

                           tuple[2] = (float)1.0;

                           vec->InsertNextTuple(tuple);

                     }

              }

       }

im->GetPointData()->SetVectors(vec);

im->GetPointData()->SetActiveVectors("v1");

 

When I try to visualise the vector field by using vtkHedgeHog now, VTK
complains that 'vtkHedgeHog (0000000003C0D9B0): No vectors in input data'.
Does somebody has a clue why?

 

Best,

Martijn

 


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