ITK  5.2.0
Insight Toolkit
Examples/Filtering/SpatialObjectToImage2.cxx
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*
* Copyright NumFOCUS
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
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*
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// Software Guide : BeginLatex
//
// This example illustrates the use of the
// \doxygen{GaussianSpatialObjects} for composing complex smoothed shapes by
// aggregating them in a group. This process is equivalent to what is called
// ''MetaBalls'' in Computer Graphics.
//
// See http://en.wikipedia.org/wiki/Metaballs
//
//
// \index{itk::SpatialObjectToImageFilter|textbf}
//
// Software Guide : EndLatex
// Software Guide : BeginLatex
//
// We include the header file of the SpatialObjectToImageFilter since we will
// use it to rasterize the group of spatial objects into an image.
//
// \index{itk::SpatialObjectToImageFilter!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Then we include the header of the GaussianSpatialObject that we will use
// as elementary shape.
//
// \index{itk::GaussianSpatialObject!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Then we include the header of the \doxygen{GroupSpatialObject} that will
// group together these instances of SpatialObjects.
//
// \index{itk::GroupSpatialObject!header}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
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 = signed short;
constexpr unsigned int Dimension = 3;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Using the same dimension, we instantiate the types of the elementary
// SpatialObjects that we plan to group, and we instantiate as well the
// type of the SpatialObject that will hold the group together.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// 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 =
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
size[0] = 50;
size[1] = 50;
size[2] = 200;
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] = 400.0 / size[2];
imageFilter->SetSpacing(spacing);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create the elementary shapes that are going to be composed into the
// group spatial objects.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
MetaBallType::Pointer metaBall1 = MetaBallType::New();
MetaBallType::Pointer metaBall2 = MetaBallType::New();
MetaBallType::Pointer metaBall3 = MetaBallType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The Elementary shapes have internal parameters of their own. These
// parameters define the geometrical characteristics of the basic shapes.
// For example, a cylinder is defined by its radius and height.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
metaBall1->SetRadiusInObjectSpace(size[0] * spacing[0] * 0.2);
metaBall2->SetRadiusInObjectSpace(size[0] * spacing[0] * 0.2);
metaBall3->SetRadiusInObjectSpace(size[0] * spacing[0] * 0.2);
// Software Guide : EndCodeSnippet
metaBall1->SetMaximum(1000.0);
metaBall2->SetMaximum(1000.0);
metaBall3->SetMaximum(1000.0);
// Software Guide : BeginLatex
//
// Each one of these components will be placed in a different position and
// orientation. We define transforms in order to specify those relative
// positions and orientations.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using TransformType = GroupType::TransformType;
TransformType::Pointer transform1 = TransformType::New();
TransformType::Pointer transform2 = TransformType::New();
TransformType::Pointer transform3 = TransformType::New();
transform1->SetIdentity();
transform2->SetIdentity();
transform3->SetIdentity();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Then we set the specific values of the transform parameters, and we
// assign the transforms to the elementary shapes.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
TransformType::OutputVectorType translation;
translation[0] = size[0] * spacing[0] / 2.0;
translation[1] = size[1] * spacing[1] / 4.0;
translation[2] = size[2] * spacing[2] / 2.0;
transform1->Translate(translation, false);
translation[1] = size[1] * spacing[1] / 2.0;
translation[2] = size[2] * spacing[2] * 0.22;
transform2->Rotate(1, 2, itk::Math::pi / 2.0);
transform2->Translate(translation, false);
translation[2] = size[2] * spacing[2] * 0.78;
transform3->Rotate(1, 2, itk::Math::pi / 2.0);
transform3->Translate(translation, false);
metaBall1->SetObjectToParentTransform(transform1);
metaBall2->SetObjectToParentTransform(transform2);
metaBall3->SetObjectToParentTransform(transform3);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The elementary shapes are aggregated in a parent group, that in turn is
// passed as input to the filter.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
GroupType::Pointer group = GroupType::New();
group->AddChild(metaBall1);
group->AddChild(metaBall2);
group->AddChild(metaBall3);
metaBall1->Update();
metaBall2->Update();
metaBall3->Update();
imageFilter->SetInput(group);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// By default, the filter will rasterize the aggregation of elementary
// shapes and will assign a pixel value to locations that fall inside of
// any of the elementary shapes, and a different pixel value to locations
// that fall outside of all of the elementary shapes. In this case, we
// actually want the values of the Gaussians (MetaBalls) to be used in
// order produce the equivalent of a smooth fusion effect among the shapes.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
const PixelType airHounsfieldUnits = -1000;
imageFilter->SetUseObjectValue(true);
imageFilter->SetOutsideValue(airHounsfieldUnits);
// 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;
}
itk::GaussianSpatialObject
Represents a multivariate Gaussian function.
Definition: itkGaussianSpatialObject.h:44
itk::GTest::TypedefsAndConstructors::Dimension2::SizeType
ImageBaseType::SizeType SizeType
Definition: itkGTestTypedefsAndConstructors.h:49
itk::SpatialObjectToImageFilter
Base class for filters that take a SpatialObject as input and produce an image as output....
Definition: itkSpatialObjectToImageFilter.h:41
itkGaussianSpatialObject.h
itkGroupSpatialObject.h
itk::ImageFileWriter
Writes image data to a single file.
Definition: itkImageFileWriter.h:87
itkSpatialObjectToImageFilter.h
itkImageFileWriter.h
itk::Size::SetSize
void SetSize(const SizeValueType val[VDimension])
Definition: itkSize.h:179
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itk::Math::pi
static constexpr double pi
Definition: itkMath.h:64
itk::GroupSpatialObject
Representation of a group based on the spatial object classes.
Definition: itkGroupSpatialObject.h:39
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44