InterpolateFieldDataDemo

VTKEx/Cxx/Meshes/InterpolateFieldDataDemo

Description

This example uses vtkPointInterpolator probe a high resolution dataset with a lower resolution dataset. Then, using vtkInterpolateDataSetAttributes, interpolate between the original low resolution data and the probed, low resolution data.

Warning

For the vtkPointInterpolator, point arrays will not be interpolated unless PassPointArrays is off. vtkPointInterpolator does not interpolate vtkFieldData. To interpolate vtkFieldData it must be added as the active scalar.

Warning

vtkInterpolateDataSetAttibutes does not interpolate vtkFieldData. To interpolate vtkFieldData it must be added as the active scalar.

Thanks

This example was inspired by Andrew E. Slaughter, Idaho National Laboratory.

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

InterpolateFieldDataDemo.cxx

// This example was derived a python script created by Andrew E. Slaughter
#include <vtkSmartPointer.h>

#include <vtkCompositeDataGeometryFilter.h>
#include <vtkExodusIIReader.h>
#include <vtkGaussianKernel.h>
#include <vtkInterpolateDataSetAttributes.h>
#include <vtkPointInterpolator.h>
#include <vtkStaticPointLocator.h>

#include <vtkNamedColors.h>
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkPolyDataMapper.h>
#include <vtkDataSetMapper.h>
#include <vtkLookupTable.h>
#include <vtkPointData.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkRenderer.h>
#include <vtkUnstructuredGrid.h>
#include <vtkMultiBlockDataSet.h>

int main (int argc, char *argv[])
{
  std::string variable = "u";
  double range[2] = {0, 10};

  if (argc < 3)
  {
    std::cout << "Usage: " << argv[0] << " coarseMesh fineMesh" << std::endl;
    return EXIT_FAILURE;
  }
  std::string file0 = argv[1];
  std::string file1 = argv[2];

  ///////////////////////////////////////////////////////////////////////////
  // FILE 0: COARSE MESH WITH SOLUTION 0
    vtkSmartPointer<vtkExodusIIReader> coarseReader =
      vtkSmartPointer<vtkExodusIIReader>::New();
    coarseReader->SetFileName(file0.c_str());
    coarseReader->UpdateInformation();
    coarseReader->SetTimeStep(0);
    coarseReader->SetAllArrayStatus(vtkExodusIIReader::NODAL, 1);
    coarseReader->Update();

    vtkSmartPointer<vtkCompositeDataGeometryFilter> coarseGeometry =
      vtkSmartPointer<vtkCompositeDataGeometryFilter>::New();
    coarseGeometry->SetInputConnection(0, coarseReader->GetOutputPort(0));
    coarseGeometry->Update();

   vtkSmartPointer<vtkPolyDataMapper> coarseMapper =
      vtkSmartPointer<vtkPolyDataMapper>::New();
    coarseMapper->SetInputConnection(coarseGeometry->GetOutputPort());
    coarseMapper->SelectColorArray(variable.c_str());
    coarseMapper->SetScalarModeToUsePointFieldData();
    coarseMapper->InterpolateScalarsBeforeMappingOn();
    coarseMapper->SetScalarRange(range);

    vtkSmartPointer<vtkActor> coarseActor =
      vtkSmartPointer<vtkActor>::New();
    coarseActor->SetMapper(coarseMapper);
    coarseActor->GetProperty()->SetEdgeVisibility(true);

    vtkSmartPointer<vtkRenderer> coarseRenderer =
      vtkSmartPointer<vtkRenderer>::New();
    coarseRenderer->AddViewProp(coarseActor);

/////////////////////////////////////////////////////////////////////
// FILE 1: FINE MESH WITH SOLUTION 1

    vtkSmartPointer<vtkExodusIIReader> fineReader =
      vtkSmartPointer<vtkExodusIIReader>::New();
    fineReader->SetFileName(file1.c_str());
    fineReader->UpdateInformation();
    fineReader->SetTimeStep(0);
    fineReader->SetAllArrayStatus(vtkExodusIIReader::NODAL, 1);
    fineReader->Update();

    vtkSmartPointer<vtkCompositeDataGeometryFilter> fineGeometry =
      vtkSmartPointer<vtkCompositeDataGeometryFilter>::New();
    fineGeometry->SetInputConnection(0, fineReader->GetOutputPort(0));
    fineGeometry->Update();
    fineGeometry->GetOutput()->GetPointData()->SetActiveScalars(variable.c_str());

    vtkSmartPointer<vtkPolyDataMapper> fineGeometryMapper =
      vtkSmartPointer<vtkPolyDataMapper>::New();
    fineGeometryMapper->SetInputConnection(fineGeometry->GetOutputPort());
    fineGeometryMapper->SelectColorArray(variable.c_str());
    fineGeometryMapper->SetScalarModeToUsePointFieldData();
    fineGeometryMapper->InterpolateScalarsBeforeMappingOn();
    fineGeometryMapper->SetScalarRange(range);

    vtkSmartPointer<vtkActor> fineGeometryActor =
      vtkSmartPointer<vtkActor>::New();
    fineGeometryActor->SetMapper(fineGeometryMapper);
    fineGeometryActor->GetProperty()->SetEdgeVisibility(true);

    vtkSmartPointer<vtkRenderer> fineGeometryRenderer =
      vtkSmartPointer<vtkRenderer>::New();
    fineGeometryRenderer->AddViewProp(fineGeometryActor);

//////////////////////////////////////////////////////////////////////
// PROJECT SOLUTION FROM FILE 0 to GRID FROM FILE 1

    // Build the structure to interpolate onto
    vtkSmartPointer<vtkUnstructuredGrid> coarseInterpolatedGrid = // output to be interpolated on to
      vtkSmartPointer<vtkUnstructuredGrid>::New();

    vtkMultiBlockDataSet *coarseMultiBlock =
      dynamic_cast<vtkMultiBlockDataSet *>(coarseReader->GetOutput()->GetBlock(0));
    coarseInterpolatedGrid->DeepCopy(dynamic_cast<vtkUnstructuredGrid*>(coarseMultiBlock->GetBlock(0)));

    vtkSmartPointer<vtkStaticPointLocator> locator =
      vtkSmartPointer<vtkStaticPointLocator>::New();
    locator->SetDataSet(fineGeometry->GetOutput());
    locator->BuildLocator();

    vtkSmartPointer<vtkGaussianKernel> kernel =
      vtkSmartPointer<vtkGaussianKernel>::New();
    kernel->SetSharpness(4);
    kernel->SetKernelFootprintToNClosest();
    kernel->SetNumberOfPoints(10);
    kernel->SetSharpness(4.0);

    // Probe the fine geometry with the course geometry.
    // NOTE: The point arrays will not be interpolated unless PassPointArrays is off.
    vtkSmartPointer<vtkPointInterpolator> coarseInterpolator =
      vtkSmartPointer<vtkPointInterpolator>::New();
    coarseInterpolator->SetSourceData(fineGeometry->GetOutput()); // Pc data set to be probed by input points P
    coarseInterpolator->SetInputData(coarseGeometry->GetOutput());
    coarseInterpolator->SetKernel(kernel);
    coarseInterpolator->SetLocator(locator);
    coarseInterpolator->SetNullPointsStrategyToClosestPoint();
    coarseInterpolator->PassPointArraysOff();
    coarseInterpolator->Update();

    vtkSmartPointer<vtkDataSetMapper> coarseInterpolatorMapper =
      vtkSmartPointer<vtkDataSetMapper>::New();
    coarseInterpolatorMapper->SetInputConnection(coarseInterpolator->GetOutputPort());
    coarseInterpolatorMapper->SelectColorArray(variable.c_str());
    coarseInterpolatorMapper->SetScalarModeToUsePointFieldData();
    coarseInterpolatorMapper->InterpolateScalarsBeforeMappingOn();
    coarseInterpolatorMapper->SetScalarRange(range);

    vtkSmartPointer<vtkActor> coarseInterpolatorActor =
      vtkSmartPointer<vtkActor>::New();
    coarseInterpolatorActor->SetMapper(coarseInterpolatorMapper);
    coarseInterpolatorActor->GetProperty()->SetEdgeVisibility(true);

    vtkSmartPointer<vtkRenderer> coarseInterpolatorRenderer =
      vtkSmartPointer<vtkRenderer>::New();
    coarseInterpolatorRenderer->AddActor(coarseInterpolatorActor);

    // Set the active scalar for the two inputs.
    // NOTE: InterpolateDataSetAttibutes does not interpolate field data.
    // To interpolate field data it must be added as the active scalar 
    coarseInterpolatedGrid->GetPointData()->SetActiveScalars(variable.c_str());
    coarseInterpolator->GetOutput()->GetPointData()->SetActiveScalars(variable.c_str());

    vtkSmartPointer<vtkInterpolateDataSetAttributes> coarseInterpolateAttributes =
      vtkSmartPointer<vtkInterpolateDataSetAttributes>::New();
    coarseInterpolateAttributes->AddInputData(0, coarseInterpolatedGrid);
    coarseInterpolateAttributes->AddInputData(0, coarseInterpolator->GetOutput());
    coarseInterpolateAttributes->SetT(0.5);
    coarseInterpolateAttributes->Update();

    vtkSmartPointer<vtkDataSetMapper> coarseInterpolateAttibutesMapper =
      vtkSmartPointer<vtkDataSetMapper>::New();
    coarseInterpolateAttibutesMapper->SetInputConnection(coarseInterpolateAttributes->GetOutputPort());
    coarseInterpolateAttibutesMapper->SelectColorArray(variable.c_str());
    coarseInterpolateAttibutesMapper->SetScalarModeToUsePointFieldData();
    coarseInterpolateAttibutesMapper->InterpolateScalarsBeforeMappingOn();
    coarseInterpolateAttibutesMapper->SetScalarRange(range);

    vtkSmartPointer<vtkActor> coarseInterpolateAttributesActor =
      vtkSmartPointer<vtkActor>::New();
    coarseInterpolateAttributesActor->SetMapper(coarseInterpolateAttibutesMapper);
    coarseInterpolateAttributesActor->GetProperty()->SetEdgeVisibility(true);

    vtkSmartPointer<vtkRenderer> coarseInterpolateAttributesRenderer =
      vtkSmartPointer<vtkRenderer>::New();
    coarseInterpolateAttributesRenderer->AddActor(coarseInterpolateAttributesActor);

/////////////////////////
//  Window and Interactor

    vtkSmartPointer<vtkRenderWindow> window =
      vtkSmartPointer<vtkRenderWindow>::New();

    // Use the same camera for each renderer
    fineGeometryRenderer->SetActiveCamera(coarseRenderer->GetActiveCamera());
    coarseInterpolatorRenderer->SetActiveCamera(coarseRenderer->GetActiveCamera());
    coarseInterpolateAttributesRenderer->SetActiveCamera(coarseRenderer->GetActiveCamera());

    // Set each renderer color
    vtkSmartPointer<vtkNamedColors> colors =
      vtkSmartPointer<vtkNamedColors>::New();
    coarseRenderer->SetBackground(
      colors->GetColor3d("Gainsboro").GetData());
    coarseInterpolatorRenderer->SetBackground(
      colors->GetColor3d("LightGrey").GetData());
    coarseInterpolateAttributesRenderer->SetBackground(
      colors->GetColor3d("Silver").GetData());
    fineGeometryRenderer->SetBackground(
      colors->GetColor3d("DarkGray").GetData());

    // Set the viewport for each renderer
    coarseRenderer->SetViewport(0, 0, 0.25, 1);
    coarseInterpolatorRenderer->SetViewport(0.25, 0, 0.5, 1);
    coarseInterpolateAttributesRenderer->SetViewport(0.5, 0, 0.75, 1);
    fineGeometryRenderer->SetViewport(0.75, 0, 1, 1);

    // Add the renderers
    window->AddRenderer(coarseRenderer);                      // low res
    window->AddRenderer(coarseInterpolatorRenderer);          // interpolated geometry
    window->AddRenderer(coarseInterpolateAttributesRenderer); // interpolated attributes
    window->AddRenderer(fineGeometryRenderer);                // hi res with point data

    // The size the window to hold 4 viewports of width 320
    window->SetSize(1280, 320);

    // Create the interactor
    vtkSmartPointer<vtkRenderWindowInteractor> interactor =
      vtkSmartPointer<vtkRenderWindowInteractor>::New();
    interactor->SetRenderWindow(window);
    window->Render();
    interactor->Initialize();

    // Reset the camera to a default view, shared by all
    coarseRenderer->ResetCamera();
    interactor->Start();

    return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(InterpolateFieldDataDemo)

find_package(VTK COMPONENTS 
  vtkvtkCommonColor
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersGeneral
  vtkvtkFiltersGeometry
  vtkvtkFiltersPoints
  vtkvtkIOExodus
  vtkvtkInteractionStyle
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping InterpolateFieldDataDemo: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(InterpolateFieldDataDemo MACOSX_BUNDLE InterpolateFieldDataDemo.cxx )
  target_link_libraries(InterpolateFieldDataDemo PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(InterpolateFieldDataDemo MACOSX_BUNDLE InterpolateFieldDataDemo.cxx )
  target_link_libraries(InterpolateFieldDataDemo PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS InterpolateFieldDataDemo
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build InterpolateFieldDataDemo

Click here to download InterpolateFieldDataDemo and its CMakeLists.txt file. Once the tarball InterpolateFieldDataDemo.tar has been downloaded and extracted,

cd InterpolateFieldDataDemo/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./InterpolateFieldDataDemo

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.