[vtkusers] NetCDF reader/writer for VTK

[Chris Hood]

   Here's a simplified version of what I use in Java. It's reads the points 
into a vtkPoints the puts it into a vtkStructuredGrid(sGrid). The data is 
read into a vtkFloatArray, which is also put into the sGrid. The changes 
for read multiple value per point into one array (such as a vector) are 
given in the code.

//General Variable Declarations
   vtkStructuredGrid sGrid = new vtkStructuredGrid();
   Array ncArray1;
   Index ncIndex1;

// Set the input file
   NetcdfFile dataFile = new NetcdfFile(inputFile);

// Read the points (I left out two dimentions)
   vtkPoints points = new vtkPoints();
   ncArray1 = dataFile.findVariable("X").read().reduce();
   ncIndex1 = ncArray1.getIndex();
   int [] size = ncArray1.getShape();
   rad = new float[(size[0]];
   for(i=0; i<size[0]; i++) rad[i] = ncArray1.getFloat(ncIndex1.set(i));
// Put points into Strucuterd Grid
   points.SetNumberOfPoints(noOfPoints[3]);         // noOfPoint 0, 1 & 2 
are the dimensions, 3 is the total # of points
   sGrid.SetDimensions(noOfPoints[0], noOfPoints[1], noOfPoints[2]);
   sGrid.SetPoints(points);

// Read the data
   vtkFloatArray arrayDensity = new vtkFloatArray();
   arrayDensity.SetNumberOfValues(noOfPoints[3]);
   ncArray1 = dataFile.findVariable("D").read().reduce();
   ncIndex1 = ncArray1.getIndex();
   for (k=0; i<noOfPoints[2]; k++) {
      for (j=0; i<noOfPoints[1]; j++) {
         for (i=0; i<noOfPoints[0]; i++) {
            arrayDensity.SetValue(i, ncArray1.getFloat(ncIndex1.set(i, j, 
k))); //
            // when reading a vector use:
            //     arrayDensity.SetTuple3(p, value1, value2, value3);
      }
   arrayDensity.SetName("Density");
   sGrid.GetPointData().AddArray(arrayDensity);



At 10:28 AM 2/3/2004, you wrote:
>I'm currently working on a project involving CFD data (curvilinear
>grids) given in NetCDF-format. Since (to my knowledge) vtk can not
>directly access these data sets I will need custom
>vtkDataReader/vtkDataWriter classes which convert the content of the
>given data files to vtk-structures and v.v. My question is if there is
>anybody here who has done this before or who knows of an implementation
>of such a reader/writer.

____________________________________
Chris Hood
Graduate Student Research Assistant
University of Colorado, Boulder
Space Environment Center - NOAA