[vtkusers] Retrieve vector data from a cell.

[Karl Mårtensson]

Abstract:

i want to retrieve a vector from a specific position in a vector field.. 

 

Concret:

We have read data using vktStructuredPoints (example data found below)

 

I now want to get the data from a specific point for instance (2.8, 2.2,
0.0)

To do this I use:

vtkCell * cell = structuredPoints->FindAndGetCell(x, NULL, -1, tol2, subId,
pcoords, weights);

the retrieve the cell that contains the data. This far there it works fine.
As long as I specify a position 

within our vector field I will retrieve a valid cell. 

 

Now I want to access the data from either one of the points in the cell
(closes neighbor) or by interpolation the data from all the points in the
cell using the point weights. Could anyone give me a hint here? 

I guess this is pretty basic for most of you but we haven’t managed to
figure it out. 

I would be glad for any suggestion!

Best regards

 

/ Karl Mårtensson

 

 

KODSNUTT:

 

vtkStructuredPoints * structuredPoints = reader->GetOutput();

      int numberOfPoints = structuredPoints->GetNumberOfPoints();

 

      double x[3];

      x[0] = position.x();

      x[1] = position.y();

      x[2] = position.z();

      double tol2 = 1;

      int subId;

      double pcoords[3];

      double weights[3];

      vtkCell * cell = structuredPoints->FindAndGetCell(x, NULL, -1, tol2,
subId, pcoords, weights);

 

      int numberOfPointsInCell;

      vtkPoints* points;

      vtkDataArray * dataArray;

      int numberOfComponents;

      int dataType;

      double * tuple0;

      double * tuple1;

      double * tuple2;

      double * tuple3;

      if (cell){

            numberOfPointsInCell = cell->GetNumberOfPoints ();

            points = cell->GetPoints();

            dataArray = points->GetData();

            numberOfComponents = dataArray->GetNumberOfComponents ();

            dataType = dataArray->GetDataType();

            // hur få vi ut datan från cellen på ett användbart sätt t.ex.
double[3]

      }

 

 

DATASNUTT:

 

# vtk DataFile Version 1.0 

Kristin Lilja & Karl Martensson 050421, Andreas Sundelöf "strömdata till
vtk-format" 

ASCII 

 

DATASET STRUCTURED_POINTS 

DIMENSIONS 10 10 1

ORIGIN 0.0 0.0 0.0 

ASPECT_RATIO 1.0 1.0 1.0 

 

POINT_DATA 100 

 

VECTORS vectors float 

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

1.0000 2.0000 3.0000

 

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