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LandmarkTransform

vtk-examples/Cxx/Filtering/LandmarkTransform


Description

This example creates two point sets which it assumes are known, ordered correspondences. It then transforms Source to Target and displays the matrix used in the transformation.

Question

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

Code

LandmarkTransform.cxx

#include <vtkActor.h>
#include <vtkCellData.h>
#include <vtkGlyph3DMapper.h>
#include <vtkLandmarkTransform.h>
#include <vtkLine.h>
#include <vtkMatrix4x4.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkTransformPolyDataFilter.h>
#include <vtkUnsignedCharArray.h>
#include <vtkVertexGlyphFilter.h>

// For compatibility with new VTK generic data arrays
#ifdef vtkGenericDataArray_h
#define InsertNextTupleValue InsertNextTypedTuple
#endif

namespace {
void AxesLines(vtkSmartPointer<vtkPolyData> linesPolyData);

/**
 * Convert points to glyphs.
 *
 * @param points - The points to glyph
 * @param scale - The scale, used to determine the size of the glyph
 * representing the point, expressed as a fraction of the largest side of the
 * bounding box surrounding the points. e.g. 0.05
 *
 * @return The actor.
 */
vtkSmartPointer<vtkActor> PointToGlyph(vtkPoints* points, double const& scale);

} // namespace

int main(int, char*[])
{
  /*
  This demo creates a coordinate frame (+x, +y, +z) of vectors and a rotated,
  peturbed frame (+z, +y, -x) and aligns the rotated frame to the original as
  best as possible.
  */

  vtkNew<vtkNamedColors> colors;

  // An aid to orient the view of the created data.
  vtkNew<vtkPolyData> linesPolyData;
  AxesLines(linesPolyData);

  vtkNew<vtkPoints> sourcePoints;
  double sourcePoint1[3] = {1.0, 0.0, 0.0};
  sourcePoints->InsertNextPoint(sourcePoint1);
  double sourcePoint2[3] = {0.0, 1.0, 0.0};
  sourcePoints->InsertNextPoint(sourcePoint2);
  double sourcePoint3[3] = {0.0, 0.0, 1.0};
  sourcePoints->InsertNextPoint(sourcePoint3);

  vtkNew<vtkPoints> targetPoints;
  double targetPoint1[3] = {0.0, 0.0, 1.1};
  targetPoints->InsertNextPoint(targetPoint1);
  double targetPoint2[3] = {0.0, 1.02, 0.0};
  targetPoints->InsertNextPoint(targetPoint2);
  double targetPoint3[3] = {-1.11, 0.0, 0.0};
  targetPoints->InsertNextPoint(targetPoint3);

  // Setup the transform
  vtkNew<vtkLandmarkTransform> landmarkTransform;
  landmarkTransform->SetSourceLandmarks(sourcePoints);
  landmarkTransform->SetTargetLandmarks(targetPoints);
  landmarkTransform->SetModeToRigidBody();
  landmarkTransform->Update(); // should this be here?

  vtkNew<vtkPolyData> source;
  source->SetPoints(sourcePoints);

  vtkNew<vtkPolyData> target;
  target->SetPoints(targetPoints);

  vtkNew<vtkVertexGlyphFilter> sourceGlyphFilter;
  sourceGlyphFilter->SetInputData(source);
  sourceGlyphFilter->Update();

  vtkNew<vtkVertexGlyphFilter> targetGlyphFilter;
  targetGlyphFilter->SetInputData(target);
  targetGlyphFilter->Update();

  vtkNew<vtkTransformPolyDataFilter> transformFilter;
  transformFilter->SetInputConnection(sourceGlyphFilter->GetOutputPort());
  transformFilter->SetTransform(landmarkTransform);
  transformFilter->Update();

  // Display the transformation matrix that was computed
  vtkMatrix4x4* mat = landmarkTransform->GetMatrix();
  std::cout << "Matrix: " << *mat << std::endl;

  // Visualize
  // Map the points to spheres
  auto sourceActor =
      PointToGlyph(sourceGlyphFilter->GetOutput()->GetPoints(), 0.03);
  sourceActor->GetProperty()->SetColor(colors->GetColor3d("Red").GetData());

  auto targetActor =
      PointToGlyph(targetGlyphFilter->GetOutput()->GetPoints(), 0.03);
  targetActor->GetProperty()->SetColor(colors->GetColor3d("Lime").GetData());

  auto solutionActor =
      PointToGlyph(transformFilter->GetOutput()->GetPoints(), 0.03);
  solutionActor->GetProperty()->SetColor(colors->GetColor3d("Blue").GetData());

  vtkNew<vtkPolyDataMapper> axesMapper;
  axesMapper->SetInputData(linesPolyData);

  vtkNew<vtkActor> axesActor;
  axesActor->SetMapper(axesMapper);
  axesActor->GetProperty()->SetLineWidth(1);

  // Create a renderer, render window, and interactor
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindow->SetWindowName("LandmarkTransform");

  // Add the actor to the scene
  renderer->AddActor(sourceActor);
  renderer->AddActor(targetActor);
  renderer->AddActor(solutionActor);
  renderer->AddActor(axesActor);

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

  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {
void AxesLines(vtkSmartPointer<vtkPolyData> linesPolyData)
{
  // Create four points
  double origin[3] = {0.0, 0.0, 0.0};
  double p0[3] = {1.2, 0.0, 0.0};
  double p1[3] = {0.0, 1.2, 0.0};
  double p2[3] = {0.0, 0.0, 1.2};

  // Create a vtkPoints container and store the points in it
  vtkNew<vtkPoints> pts;
  pts->InsertNextPoint(origin);
  pts->InsertNextPoint(p0);
  pts->InsertNextPoint(p1);
  pts->InsertNextPoint(p2);

  // Add the points to the polydata container
  linesPolyData->SetPoints(pts);

  // Create the lines (between Origin and p0, ,p1, p2)
  vtkNew<vtkLine> line0;
  line0->GetPointIds()->SetId(0, 0);
  line0->GetPointIds()->SetId(1, 1);
  vtkNew<vtkLine> line1;
  line1->GetPointIds()->SetId(0, 0);
  line1->GetPointIds()->SetId(1, 2);
  vtkNew<vtkLine> line2;
  line2->GetPointIds()->SetId(0, 0);
  line2->GetPointIds()->SetId(1, 3);

  // Create a vtkCellArray container and store the lines in it
  vtkNew<vtkCellArray> lines;
  lines->InsertNextCell(line0);
  lines->InsertNextCell(line1);
  lines->InsertNextCell(line2);

  // Add the lines to the polydata container
  linesPolyData->SetLines(lines);

  vtkNew<vtkNamedColors> namedColors;

  // Create a vtkUnsignedCharArray container and store the colors in it
  vtkNew<vtkUnsignedCharArray> colors;
  colors->SetNumberOfComponents(3);
  colors->InsertNextTupleValue(namedColors->GetColor3ub("DarkRed").GetData());
  colors->InsertNextTupleValue(namedColors->GetColor3ub("DarkGreen").GetData());
  colors->InsertNextTupleValue(
      namedColors->GetColor3ub("MidnightBlue").GetData());

  // Color the lines.
  linesPolyData->GetCellData()->SetScalars(colors);
}

vtkSmartPointer<vtkActor> PointToGlyph(vtkPoints* points, double const& scale)
{
  auto bounds = points->GetBounds();
  double maxLen = 0;
  for (int i = 1; i < 3; ++i)
  {
    maxLen = std::max(bounds[i + 1] - bounds[i], maxLen);
  }

  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetRadius(scale * maxLen);

  vtkNew<vtkPolyData> pd;
  pd->SetPoints(points);

  vtkNew<vtkGlyph3DMapper> mapper;
  mapper->SetInputData(pd);
  mapper->SetSourceConnection(sphereSource->GetOutputPort());
  mapper->ScalarVisibilityOff();
  mapper->ScalingOff();

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);

  return actor;
}

} // namespace```
###CMakeLists.txt
```cmake
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(LandmarkTransform)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkCommonMath
  vtkCommonTransforms
  vtkFiltersGeneral
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping LandmarkTransform: ${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(LandmarkTransform MACOSX_BUNDLE LandmarkTransform.cxx )
  target_link_libraries(LandmarkTransform PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(LandmarkTransform MACOSX_BUNDLE LandmarkTransform.cxx )
  target_link_libraries(LandmarkTransform PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS LandmarkTransform
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build LandmarkTransform

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

cd LandmarkTransform/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:

./LandmarkTransform

WINDOWS USERS

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