Dune-Vtk

File reader and writer for the VTK Format

Summary

Provides structured and unstructured file writers for the VTK XML File Formats that can be opened in the popular ParaView visualization application. Additionally a file reader is provided to import VTK files into Dune grid and data objects.

Usage

The VTK writer works similar to the dune-grid VTKWriter. It needs to be bound to a GridView and then data can be added to the points or cells in the grid. Points are not necessarily grid vertices, but any coordinates places inside the grid cells, so the data must be provided as GridViewFunction to allow the local evaluation in arbitrary local coordinates.

Grid grid = ...;
VtkWriter<typename Grid::LeafGridView> vtkWriter(grid.leafGridView());

auto fct = makeAnalyticGridViewFunction([](auto const& x) {
  return std::sin(x[0]);
});

vtkWriter.addPointData(fct, "u_points");
vtkWriter.addCellData(fct, "u_cells");

vtkWriter.write("filename.vtu", Vtk::ASCII);

See also the src/ directory for more examples.

Comparison with Dune::VTKWriter

In Dune-Grid there is a VTK writer available, that is a bit different from the proposed one. A comparions:

Example

Create a fine structured YaspGrid and write it in parallel with 8 cores with different write modi:

1. Create the grid

const int dim = 3;
FieldVector<double,dim> upperRight; upperRight = 1.0;
auto numElements = filledArray<dim,int>(16);
YaspGrid<dim> grid(upperRight,numElements,0,0); // no overlap
grid.globalRefine(3);
auto gridView = grid.leafGridView();

2. Create a function to write

auto fct = makeAnalyticGridViewFunction([](auto const& x) {
  return std::sin(10*x[0]) * std::cos(10*x[1]) + std::sin(10*x[2]);
}, gridView);

3. Write the grid and data to file

Vtk[FORMAT]Writer<decltype(gridView)> vtkWriter(gridView);
vtkWriter.addPointData(fct, "fct");
vtkWriter.write("filename.vtu", [FORMAT_TYPE], [DATA_TYPE]);

where FORMAT one of

• UnstructuredGrid,
• StructuredGrid (structured connectivity, arbitrary coordinates),
• RectilinearGrid (structured connectivity, tensor-product coordinates), or
• ImageData (structured connectivity, axis-parallel coordinates with constant grid-spacing),

FORMAT_TYPE one of

• Vtk::ASCII (inline ascii format),
• Vtk::BINARY (appended raw format), or
• Vtk::COMPRESSED (appended compressed raw format),

and DATA_TYPE one of

• Vtk::FLOAT32 (single precision), or
• Vtk::FLOAT64 (double precision).

We measure the file size (per processor) and the memory requirement of ParaView to visualize the data.