InterpolateFieldDataDemo

VTKExamples/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.

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 =
      vtkMultiBlockDataSet::SafeDownCast(coarseReader->GetOutput()->GetBlock(0));
    coarseInterpolatedGrid->DeepCopy(vtkUnstructuredGrid::SafeDownCast(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);
    interactor->Initialize();

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

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(InterpolateFieldDataDemo)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(InterpolateFieldDataDemo MACOSX_BUNDLE InterpolateFieldDataDemo.cxx )

target_link_libraries(InterpolateFieldDataDemo ${VTK_LIBRARIES})

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.