Examples/Filtering/SpatialObjectToImage3.cxx

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 *  Copyright NumFOCUS
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//  Software Guide : BeginLatex
//
//  This example illustrates the use of the
//  \doxygen{PolygonSpatialObject} for generating a binary image through the
//  \doxygen{SpatialObjectToImageFilter}.
//
//  \index{itk::PolygonSpatialObject|textbf}
//  \index{itk::SpatialObjectToImageFilter|textbf}
//
//  We start by including the header of the PolygonSpatialObject that we will
//  use as elementary shape, and the header for the SpatialObjectToImageFilter
//  that we will use to rasterize the SpatialObject.
//
//  \index{itk::PolygonSpatialObject!header}
//  \index{itk::SpatialObjectToImageFilter!header}
//
//  Software Guide : EndLatex
 
 
// Software Guide : BeginCodeSnippet
#include "itkPolygonSpatialObject.h"
#include "itkSpatialObjectToImageFilter.h"
// Software Guide : EndCodeSnippet
 
 
#include "itkImageFileWriter.h"
 
 
int
main(int argc, char * argv[])
{
  if (argc != 2)
  {
    std::cerr << "Usage: " << argv[0] << " outputimagefile " << std::endl;
    return EXIT_FAILURE;
  }
 
 
  //  Software Guide : BeginLatex
  //
  //  We declare the pixel type and dimension of the image to be produced as
  //  output.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using PixelType = unsigned char;
  constexpr unsigned int Dimension = 3;
 
  using ImageType = itk::Image<PixelType, Dimension>;
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  Using the same dimension, we instantiate the types of the elementary
  //  SpatialObjects that we plan to rasterize.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using PolygonType = itk::PolygonSpatialObject<Dimension>;
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  We instantiate the SpatialObjectToImageFilter type by using as template
  //  arguments the input SpatialObject and the output image types.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using SpatialObjectToImageFilterType =
    itk::SpatialObjectToImageFilter<PolygonType, ImageType>;
 
  SpatialObjectToImageFilterType::Pointer imageFilter =
    SpatialObjectToImageFilterType::New();
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  The SpatialObjectToImageFilter requires that the user defines the grid
  //  parameters of the output image. This includes the number of pixels along
  //  each dimension, the pixel spacing, image direction and
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  ImageType::SizeType size;
  size[0] = 100;
  size[1] = 100;
  size[2] = 1;
 
  imageFilter->SetSize(size);
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginCodeSnippet
  ImageType::SpacingType spacing;
  spacing[0] = 100.0 / size[0];
  spacing[1] = 100.0 / size[1];
  spacing[2] = 1.0;
 
  imageFilter->SetSpacing(spacing);
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  We create the polygon object.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  PolygonType::Pointer polygon = PolygonType::New();
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  We populate the points of the polygon by computing the edges of a
  //  hexagon centered in the image.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  constexpr unsigned int                      numberOfPoints = 6;
  typename PolygonType::PointType             point;
  typename PolygonType::PointType::VectorType radial;
  radial[0] = 0.0;
  radial[1] = 0.0;
  radial[2] = 0.0;
 
  typename PolygonType::PointType center;
  center[0] = 50.0;
  center[1] = 50.0;
  center[2] = 0.0;
 
  constexpr double radius = 40.0;
 
  typename PolygonType::PolygonPointType polygonPoint;
 
  for (unsigned int i = 0; i < numberOfPoints; i++)
  {
    const double angle = 2.0 * itk::Math::pi * i / numberOfPoints;
    radial[0] = radius * std::cos(angle);
    radial[1] = radius * std::sin(angle);
    point = center + radial;
    polygonPoint.SetPositionInObjectSpace(point);
    polygon->GetPoints().push_back(polygonPoint);
  }
  polygon->SetIsClosed(true);
  polygon->Update();
  // Software Guide : EndCodeSnippet
 
  std::cout << "Polygon Perimeter = "
            << polygon->MeasurePerimeterInObjectSpace() << std::endl;
  std::cout << "Polygon Area      = " << polygon->MeasureAreaInObjectSpace()
            << std::endl;
 
  //  Software Guide : BeginLatex
  //
  //  We connect the polygon as the input to the SpatialObjectToImageFilter.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  imageFilter->SetInput(polygon);
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  Finally we are ready to run the filter. We use the typical invocation of
  //  the \code{Update} method, and we instantiate an \code{ImageFileWriter}
  //  in order to save the generated image into a file.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using WriterType = itk::ImageFileWriter<ImageType>;
  WriterType::Pointer writer = WriterType::New();
 
  writer->SetFileName(argv[1]);
  writer->SetInput(imageFilter->GetOutput());
 
  try
  {
    imageFilter->Update();
    writer->Update();
  }
  catch (const itk::ExceptionObject & excp)
  {
    std::cerr << excp << std::endl;
    return EXIT_FAILURE;
  }
  // Software Guide : EndCodeSnippet
 
 
  return EXIT_SUCCESS;
}