PolyDataContourToImageData
VTKExamples/Cxx/PolyData/PolyDataContourToImageData
Description
- Contributed by: Lars Friedrich
This example generates a sphere, cuts it with a plane and, therefore, generates a circlular contour (vtkPolyData). Subsequently a binary image representation (vtkImageData) is extracted from it. Internally vtkPolyDataToImageStencil and vtkLinearExtrusionFilter are utilized. Both the circular poly data (circle.vtp) and the resultant image (labelImage.mhd) are saved to disk.
NOTE: Similarily to example PolyDataToImageData, I am not really sure whether or not the image origin needs to be adjusted as the sphere-image-overlay shows some offset in paraview visualization (at least I think ...). Maybe someone could verify that. Thanks!
Code
PolyDataContourToImageData.cxx
#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkImageData.h>
#include <vtkSphereSource.h>
#include <vtkMetaImageWriter.h>
#include <vtkPolyDataToImageStencil.h>
#include <vtkImageStencil.h>
#include <vtkPointData.h>
#include <vtkCutter.h>
#include <vtkPlane.h>
#include <vtkStripper.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkXMLPolyDataWriter.h>
/**
* This example generates a sphere, cuts it with a plane and, therefore, generates a circlular contour (vtkPolyData).
* Subsequently a binary image representation (vtkImageData) is extracted from it. Internally vtkPolyDataToImageStencil and
* vtkLinearExtrusionFilter are utilized. Both the circular poly data (circle.vtp) and the resultant image (labelImage.mhd)
* are saved to disk.
*/
int main(int, char *[])
{
// 3D source sphere
vtkSmartPointer<vtkSphereSource> sphereSource =
vtkSmartPointer<vtkSphereSource>::New();
sphereSource->SetPhiResolution(30);
sphereSource->SetThetaResolution(30);
sphereSource->SetCenter(40, 40, 0);
sphereSource->SetRadius(20);
// generate circle by cutting the sphere with an implicit plane
// (through its center, axis-aligned)
vtkSmartPointer<vtkCutter> circleCutter = vtkSmartPointer<vtkCutter>::New();
circleCutter->SetInputConnection(sphereSource->GetOutputPort());
vtkSmartPointer<vtkPlane> cutPlane = vtkSmartPointer<vtkPlane>::New();
cutPlane->SetOrigin(sphereSource->GetCenter());
cutPlane->SetNormal(0, 0, 1);
circleCutter->SetCutFunction(cutPlane);
vtkSmartPointer<vtkStripper> stripper = vtkSmartPointer<vtkStripper>::New();
stripper->SetInputConnection(circleCutter->GetOutputPort()); // valid circle
stripper->Update();
// that's our circle
vtkSmartPointer<vtkPolyData> circle = stripper->GetOutput();
// write circle out
vtkSmartPointer<vtkXMLPolyDataWriter> polyDataWriter =
vtkSmartPointer<vtkXMLPolyDataWriter>::New();
#if VTK_MAJOR_VERSION <= 5
polyDataWriter->SetInput(circle);
#else
polyDataWriter->SetInputData(circle);
#endif
polyDataWriter->SetFileName("circle.vtp");
polyDataWriter->SetCompressorTypeToNone();
polyDataWriter->SetDataModeToAscii();
polyDataWriter->Write();
// prepare the binary image's voxel grid
vtkSmartPointer<vtkImageData> whiteImage =
vtkSmartPointer<vtkImageData>::New();
double bounds[6];
circle->GetBounds(bounds);
double spacing[3]; // desired volume spacing
spacing[0] = 0.5;
spacing[1] = 0.5;
spacing[2] = 0.5;
whiteImage->SetSpacing(spacing);
// compute dimensions
int dim[3];
for (int i = 0; i < 3; i++)
{
dim[i] = static_cast<int>(ceil((bounds[i * 2 + 1] - bounds[i * 2]) /
spacing[i])) + 1;
if (dim[i] < 1)
dim[i] = 1;
}
whiteImage->SetDimensions(dim);
whiteImage->SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1);
double origin[3];
// NOTE: I am not sure whether or not we had to add some offset!
origin[0] = bounds[0];// + spacing[0] / 2;
origin[1] = bounds[2];// + spacing[1] / 2;
origin[2] = bounds[4];// + spacing[2] / 2;
whiteImage->SetOrigin(origin);
#if VTK_MAJOR_VERSION <= 5
whiteImage->SetScalarTypeToUnsignedChar();
whiteImage->AllocateScalars();
#else
whiteImage->AllocateScalars(VTK_UNSIGNED_CHAR,1);
#endif
// fill the image with foreground voxels:
unsigned char inval = 255;
unsigned char outval = 0;
vtkIdType count = whiteImage->GetNumberOfPoints();
for (vtkIdType i = 0; i < count; ++i)
{
whiteImage->GetPointData()->GetScalars()->SetTuple1(i, inval);
}
// sweep polygonal data (this is the important thing with contours!)
vtkSmartPointer<vtkLinearExtrusionFilter> extruder =
vtkSmartPointer<vtkLinearExtrusionFilter>::New();
#if VTK_MAJOR_VERSION <= 5
extruder->SetInput(circle);
#else
extruder->SetInputData(circle);
#endif
extruder->SetScaleFactor(1.);
extruder->SetExtrusionTypeToNormalExtrusion();
extruder->SetVector(0, 0, 1);
extruder->Update();
// polygonal data --> image stencil:
vtkSmartPointer<vtkPolyDataToImageStencil> pol2stenc =
vtkSmartPointer<vtkPolyDataToImageStencil>::New();
pol2stenc->SetTolerance(0); // important if extruder->SetVector(0, 0, 1) !!!
pol2stenc->SetInputConnection(extruder->GetOutputPort());
pol2stenc->SetOutputOrigin(origin);
pol2stenc->SetOutputSpacing(spacing);
pol2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
pol2stenc->Update();
// cut the corresponding white image and set the background:
vtkSmartPointer<vtkImageStencil> imgstenc =
vtkSmartPointer<vtkImageStencil>::New();
#if VTK_MAJOR_VERSION <= 5
imgstenc->SetInput(whiteImage);
imgstenc->SetStencil(pol2stenc->GetOutput());
#else
imgstenc->SetInputData(whiteImage);
imgstenc->SetStencilConnection(pol2stenc->GetOutputPort());
#endif
imgstenc->ReverseStencilOff();
imgstenc->SetBackgroundValue(outval);
imgstenc->Update();
vtkSmartPointer<vtkMetaImageWriter> imageWriter =
vtkSmartPointer<vtkMetaImageWriter>::New();
imageWriter->SetFileName("labelImage.mhd");
imageWriter->SetInputConnection(imgstenc->GetOutputPort());
imageWriter->Write();
return EXIT_SUCCESS;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(PolyDataContourToImageData)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(PolyDataContourToImageData MACOSX_BUNDLE PolyDataContourToImageData.cxx)
target_link_libraries(PolyDataContourToImageData ${VTK_LIBRARIES})
Download and Build PolyDataContourToImageData
Click here to download PolyDataContourToImageData and its CMakeLists.txt file. Once the tarball PolyDataContourToImageData.tar has been downloaded and extracted,
cd PolyDataContourToImageData/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:
./PolyDataContourToImageData
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.