PolyDataContourToImageData
web-test/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 [vtkPolyData](https://www.vtk.org/doc/nightly/html/classvtkPolyData.html#details)ToImageStencil and vtkLinearExtrusionFilter are utilized. Both the circular poly data (circle.vtp) and the resultant image (labelImage.mhd) are saved to disk.
Note
Similar 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!
Other languages
See (Python)
Question
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Code¶
PolyDataContourToImageData.cxx
#include <vtkCutter.h>
#include <vtkImageData.h>
#include <vtkImageStencil.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkMetaImageWriter.h>
#include <vtkNew.h>
#include <vtkPlane.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkPolyDataToImageStencil.h>
#include <vtkSphereSource.h>
#include <vtkStripper.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
vtkNew<vtkSphereSource> sphereSource;
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)
vtkNew<vtkCutter> circleCutter;
circleCutter->SetInputConnection(sphereSource->GetOutputPort());
vtkNew<vtkPlane> cutPlane;
cutPlane->SetOrigin(sphereSource->GetCenter());
cutPlane->SetNormal(0, 0, 1);
circleCutter->SetCutFunction(cutPlane);
vtkNew<vtkStripper> stripper;
stripper->SetInputConnection(circleCutter->GetOutputPort()); // valid circle
stripper->Update();
// that's our circle
auto circle = stripper->GetOutput();
// write circle out
vtkNew<vtkXMLPolyDataWriter> polyDataWriter;
polyDataWriter->SetInputData(circle);
polyDataWriter->SetFileName("circle.vtp");
polyDataWriter->SetCompressorTypeToNone();
polyDataWriter->SetDataModeToAscii();
polyDataWriter->Write();
// prepare the binary image's voxel grid
vtkNew<vtkImageData> whiteImage;
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);
whiteImage->AllocateScalars(VTK_UNSIGNED_CHAR, 1);
// 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!)
vtkNew<vtkLinearExtrusionFilter> extruder;
extruder->SetInputData(circle);
extruder->SetScaleFactor(1.);
extruder->SetExtrusionTypeToVectorExtrusion();
extruder->SetVector(0, 0, 1);
extruder->Update();
// polygonal data --> image stencil:
vtkNew<vtkPolyDataToImageStencil> pol2stenc;
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:
vtkNew<vtkImageStencil> imgstenc;
imgstenc->SetInputData(whiteImage);
imgstenc->SetStencilConnection(pol2stenc->GetOutputPort());
imgstenc->ReverseStencilOff();
imgstenc->SetBackgroundValue(outval);
imgstenc->Update();
imgstenc->GetOutput()->Print(std::cout);
vtkNew<vtkMetaImageWriter> imageWriter;
imageWriter->SetFileName("labelImage.mhd");
imageWriter->SetInputConnection(imgstenc->GetOutputPort());
imageWriter->Write();
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
project(PolyDataContourToImageData)
find_package(VTK COMPONENTS
CommonCore
CommonDataModel
FiltersCore
FiltersModeling
FiltersSources
IOImage
IOXML
ImagingStencil
)
if (NOT VTK_FOUND)
message(FATAL_ERROR "PolyDataContourToImageData: 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(PolyDataContourToImageData MACOSX_BUNDLE PolyDataContourToImageData.cxx )
target_link_libraries(PolyDataContourToImageData PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS PolyDataContourToImageData
MODULES ${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
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.