// ITK #include "itkLineCell.h" #include "itkMesh.h" #include "itkTriangleCell.h" #include "itkQuadrilateralCell.h" // VTK #include "vtkVersion.h" #include <vtkCellArray.h> #include <vtkSmartPointer.h> #include <vtkUnstructuredGrid.h> #include <vtkXMLUnstructuredGridWriter.h> typedef itk::Mesh< float, 3 > MeshType; // Functions static MeshType::Pointer CreateMeshWithEdges(); static void ConvertMeshToUnstructuredGrid(MeshType::Pointer, vtkUnstructuredGrid*); class VisitVTKCellsClass { vtkCellArray* m_Cells; int* m_LastCell; int* m_TypeArray; public: // typedef the itk cells we are interested in typedef itk::CellInterface< MeshType::PixelType, MeshType::CellTraits > CellInterfaceType; typedef itk::LineCell<CellInterfaceType> floatLineCell; typedef itk::TriangleCell<CellInterfaceType> floatTriangleCell; typedef itk::QuadrilateralCell<CellInterfaceType> floatQuadrilateralCell; // Set the vtkCellArray that will be constructed void SetCellArray(vtkCellArray* a) { m_Cells = a; } // Set the cell counter pointer void SetCellCounter(int* i) { m_LastCell = i; } // Set the type array for storing the vtk cell types void SetTypeArray(int* i) { m_TypeArray = i; } // Visit a triangle and create the VTK_TRIANGLE cell void Visit(unsigned long, floatTriangleCell* t) { m_Cells->InsertNextCell(3, (vtkIdType*)t->PointIdsBegin()); m_TypeArray[*m_LastCell] = VTK_TRIANGLE; (*m_LastCell)++; } // Visit a triangle and create the VTK_QUAD cell void Visit(unsigned long, floatQuadrilateralCell* t) { m_Cells->InsertNextCell(4, (vtkIdType*)t->PointIdsBegin()); m_TypeArray[*m_LastCell] = VTK_QUAD; (*m_LastCell)++; } // Visit a line and create the VTK_LINE cell void Visit(unsigned long, floatLineCell* t) { m_Cells->InsertNextCell(2, (vtkIdType*)t->PointIdsBegin()); m_TypeArray[*m_LastCell] = VTK_LINE; (*m_LastCell)++; } }; int main(int, char *[]) { MeshType::Pointer mesh = CreateMeshWithEdges(); vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid = vtkSmartPointer<vtkUnstructuredGrid>::New(); ConvertMeshToUnstructuredGrid(mesh, unstructuredGrid); // Write file vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer = vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New(); writer->SetFileName("output.vtu"); #if VTK_MAJOR_VERSION <= 5 writer->SetInputConnection(unstructuredGrid->GetProducerPort()); #else writer->SetInputData(unstructuredGrid); #endif writer->Write(); return EXIT_SUCCESS; } MeshType::Pointer CreateMeshWithEdges() { MeshType::Pointer mesh = MeshType::New(); // Create 4 points and add them to the mesh MeshType::PointType p0,p1,p2,p3; p0[0]= -1.0; p0[1]= -1.0; p0[2]= 0.0; p1[0]= 1.0; p1[1]= -1.0; p1[2]= 0.0; p2[0]= 1.0; p2[1]= 1.0; p2[2]= 0.0; p3[0]= 1.0; p3[1]= 1.0; p3[2]= 1.0; mesh->SetPoint( 0, p0 ); mesh->SetPoint( 1, p1 ); mesh->SetPoint( 2, p2 ); mesh->SetPoint( 3, p3 ); // Create three lines and add them to the mesh typedef MeshType::CellType::CellAutoPointer CellAutoPointer; typedef itk::LineCell< MeshType::CellType > LineType; CellAutoPointer line0; line0.TakeOwnership( new LineType ); line0->SetPointId(0, 0); // line between points 0 and 1 line0->SetPointId(1, 1); mesh->SetCell( 0, line0); CellAutoPointer line1; line1.TakeOwnership( new LineType ); line1->SetPointId(0, 1); // line between points 1 and 2 line1->SetPointId(1, 2); mesh->SetCell( 1, line1); CellAutoPointer line2; line2.TakeOwnership( new LineType ); line2->SetPointId(0, 2); // line between points 2 and 3 line2->SetPointId(1, 3); mesh->SetCell( 2, line2); return mesh; } void ConvertMeshToUnstructuredGrid(MeshType::Pointer mesh, vtkUnstructuredGrid* unstructuredGrid) { // Get the number of points in the mesh int numPoints = mesh->GetNumberOfPoints(); if(numPoints == 0) { mesh->Print(std::cerr); std::cerr << "no points in Grid " << std::endl; exit(-1); } // Create the vtkPoints object and set the number of points vtkPoints* vpoints = vtkPoints::New(); vpoints->SetNumberOfPoints(numPoints); // Iterate over all the points in the itk mesh filling in // the vtkPoints object as we go MeshType::PointsContainer::Pointer points = mesh->GetPoints(); // In ITK the point container is not necessarily a vector, but in VTK it is vtkIdType VTKId = 0; std::map< vtkIdType, int > IndexMap; for(MeshType::PointsContainer::Iterator i = points->Begin(); i != points->End(); ++i, VTKId++) { // Get the point index from the point container iterator IndexMap[ VTKId ] = i->Index(); // Set the vtk point at the index with the the coord array from itk // itk returns a const pointer, but vtk is not const correct, so // we have to use a const cast to get rid of the const vpoints->SetPoint(VTKId, const_cast<float*>(i->Value().GetDataPointer())); } // Set the points on the vtk grid unstructuredGrid->SetPoints(vpoints); // Setup some VTK things int vtkCellCount = 0; // running counter for current cell being inserted into vtk int numCells = mesh->GetNumberOfCells(); int *types = new int[numCells]; // type array for vtk // create vtk cells and estimate the size vtkCellArray* cells = vtkCellArray::New(); cells->EstimateSize(numCells, 4); // Setup the line visitor typedef itk::CellInterfaceVisitorImplementation< float, MeshType::CellTraits, itk::LineCell< itk::CellInterface<MeshType::PixelType, MeshType::CellTraits > >, VisitVTKCellsClass> LineVisitor; LineVisitor::Pointer lv = LineVisitor::New(); lv->SetTypeArray(types); lv->SetCellCounter(&vtkCellCount); lv->SetCellArray(cells); // Setup the triangle visitor typedef itk::CellInterfaceVisitorImplementation< float, MeshType::CellTraits, itk::TriangleCell< itk::CellInterface<MeshType::PixelType, MeshType::CellTraits > >, VisitVTKCellsClass> TriangleVisitor; TriangleVisitor::Pointer tv = TriangleVisitor::New(); tv->SetTypeArray(types); tv->SetCellCounter(&vtkCellCount); tv->SetCellArray(cells); // Setup the quadrilateral visitor typedef itk::CellInterfaceVisitorImplementation< float, MeshType::CellTraits, itk::QuadrilateralCell< itk::CellInterface<MeshType::PixelType, MeshType::CellTraits > >, VisitVTKCellsClass> QuadrilateralVisitor; QuadrilateralVisitor::Pointer qv = QuadrilateralVisitor::New(); qv->SetTypeArray(types); qv->SetCellCounter(&vtkCellCount); qv->SetCellArray(cells); // Add the visitors to a multivisitor MeshType::CellType::MultiVisitor::Pointer mv = MeshType::CellType::MultiVisitor::New(); mv->AddVisitor(tv); mv->AddVisitor(qv); mv->AddVisitor(lv); // Now ask the mesh to accept the multivisitor which // will Call Visit for each cell in the mesh that matches the // cell types of the visitors added to the MultiVisitor mesh->Accept(mv); // Now set the cells on the vtk grid with the type array and cell array unstructuredGrid->SetCells(types, cells); std::cout << "Unstructured grid has " << unstructuredGrid->GetNumberOfCells() << " cells." << std::endl; // Clean up vtk objects cells->Delete(); vpoints->Delete(); }
cmake_minimum_required(VERSION 2.8) project(ConvertToVTK) find_package(ITK REQUIRED) include(${ITK_USE_FILE}) if (ITKVtkGlue_LOADED) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) else() find_package(ItkVtkGlue REQUIRED) include(${ItkVtkGlue_USE_FILE}) set(Glue ItkVtkGlue) endif() add_executable(ConvertToVTK MACOSX_BUNDLE ConvertToVTK.cxx) target_link_libraries(ConvertToVTK ${Glue} ${VTK_LIBRARIES} ${ITK_LIBRARIES})
Click here to download ConvertToVTK. and its CMakeLists.txt file. Once the tarball ConvertToVTK.tar has been downloaded and extracted,
cd ConvertToVTK/build
cmake ..
cmake -DITK_DIR:PATH=/home/me/itk_build ..
Build the project,
make
and run it:
./ConvertToVTK
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK and ITK bin directories to your path. This will resolve the VTK and ITK dll's at run time.
Many of the examples in the ITK Wiki Examples Collection require VTK. You can build all of the the examples by following these instructions. If you are a new VTK user, you may want to try the Superbuild which will build a proper ITK and VTK.
For examples that use QuickView (which depends on VTK), you must have built ITK with Module_ITKVtkGlue=ON.
Some of the ITK Examples require VTK to display the images. If you download the entire ITK Wiki Examples Collection, the ItkVtkGlue directory will be included and configured. If you wish to just build a few examples, then you will need to download ItkVtkGlue and build it. When you run cmake it will ask you to specify the location of the ItkVtkGlue binary directory.