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ShepardInterpolation

vtk-examples/Cxx/Visualization/ShepardInterpolation

Description

Use vtkShepardMethod to interpolate the scalars of a vtkPolyData. The zero-contour of the original and interpoltated scalars are extracted with vtkContourFilter. The original data is shown in red and the interpolated data in shown in yellow.

Usage:

ShepardInterpolation polydata [resolution]

where: - polydata is a polydata file with scalar data. - resolution is the sampling resoluton, default 100.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

ShepardInterpolation.cxx

#include <vtkActor.h>
#include <vtkBYUReader.h>
#include <vtkCamera.h>
#include <vtkContourFilter.h>
#include <vtkImageData.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkOBJReader.h>
#include <vtkPLYReader.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyDataReader.h>
#include <vtkProbeFilter.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSTLReader.h>
#include <vtkShepardMethod.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkXMLPolyDataReader.h>

#include <vtksys/SystemTools.hxx>

#include <iostream>
#include <string>

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName);
}

int main(int argc, char* argv[])
{
  // Parse input arguments.
  if (argc < 3)
  {
    std::cout
        << "Required parameters: Filename  resolution e.g. cowHead.vtp 100"
        << std::endl;
    return EXIT_FAILURE;
  }

  vtkNew<vtkNamedColors> colors;

  auto polyData = ReadPolyData(argc > 1 ? argv[1] : "");

  unsigned int resolution = 100;
  if (argc >= 3)
  {
    resolution = std::atoi(argv[2]);
  }
  vtkNew<vtkShepardMethod> interpolator;
  interpolator->SetInputData(polyData);
  interpolator->SetModelBounds(polyData->GetBounds());
  interpolator->SetSampleDimensions(resolution, resolution, resolution);
  interpolator->SetNullValue(-10000);
  interpolator->Update();
  std::cout << "Scalar Range: "
            << interpolator->GetOutput()->GetScalarRange()[0] << ", "
            << interpolator->GetOutput()->GetScalarRange()[1] << std::endl;

  vtkNew<vtkProbeFilter> probe;
  probe->SetInputData(0, polyData);
  probe->SetInputConnection(1, interpolator->GetOutputPort());

  vtkNew<vtkContourFilter> interpolatedContour;
  interpolatedContour->SetInputConnection(probe->GetOutputPort());
  interpolatedContour->SetValue(0, 0.0);

  vtkNew<vtkContourFilter> originalContour;
  originalContour->SetInputData(polyData);
  originalContour->SetValue(0, 0.0);

  vtkNew<vtkPolyDataMapper> interpolatedMapper;
  interpolatedMapper->SetInputConnection(interpolatedContour->GetOutputPort());
  interpolatedMapper->ScalarVisibilityOff();

  vtkNew<vtkActor> interpolatedActor;
  interpolatedActor->SetMapper(interpolatedMapper);
  interpolatedActor->GetProperty()->SetColor(
      colors->GetColor3d("Banana").GetData());
  interpolatedActor->GetProperty()->SetLineWidth(4.0);

  vtkNew<vtkPolyDataMapper> originalMapper;
  originalMapper->SetInputConnection(originalContour->GetOutputPort());
  originalMapper->ScalarVisibilityOff();

  vtkNew<vtkActor> originalActor;
  originalActor->SetMapper(originalMapper);
  originalActor->GetProperty()->SetColor(
      colors->GetColor3d("Tomato").GetData());
  originalActor->GetProperty()->SetLineWidth(4.0);
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("ShepardInterpolation");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(interpolatedActor);
  renderer->AddActor(originalActor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Azimuth(120);
  renderer->GetActiveCamera()->Elevation(30);
  renderer->GetActiveCamera()->Dolly(1.5);
  renderer->ResetCameraClippingRange();

  renderWindow->SetSize(640, 480);
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName)
{
  vtkSmartPointer<vtkPolyData> polyData;
  std::string extension =
      vtksys::SystemTools::GetFilenameExtension(std::string(fileName));
  if (extension == ".ply")
  {
    vtkNew<vtkPLYReader> reader;
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtp")
  {
    vtkNew<vtkXMLPolyDataReader> reader;
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".obj")
  {
    vtkNew<vtkOBJReader> reader;
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".stl")
  {
    vtkNew<vtkSTLReader> reader;
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtk")
  {
    vtkNew<vtkPolyDataReader> reader;
    reader->SetFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".g")
  {
    vtkNew<vtkBYUReader> reader;
    reader->SetGeometryFileName(fileName);
    reader->Update();
    polyData = reader->GetOutput();
  }
  else
  {
    vtkNew<vtkSphereSource> source;
    source->Update();
    polyData = source->GetOutput();
  }
  return polyData;
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ShepardInterpolation)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ShepardInterpolation: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(ShepardInterpolation MACOSX_BUNDLE ShepardInterpolation.cxx )
  target_link_libraries(ShepardInterpolation PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ShepardInterpolation
  MODULES ${VTK_LIBRARIES}
)

Download and Build ShepardInterpolation

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

cd ShepardInterpolation/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:

./ShepardInterpolation

WINDOWS USERS

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