ITK  5.0.0
Insight Segmentation and Registration Toolkit
Examples/Filtering/SpatialObjectToImage2.cxx
/*=========================================================================
*
* Copyright Insight Software Consortium
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
// 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 = itk::SpatialObjectToImageFilter<
GroupType, 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
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
WriterType::Pointer writer = WriterType::New();
writer->SetFileName( argv[1] );
writer->SetInput( imageFilter->GetOutput() );
try
{
imageFilter->Update();
writer->Update();
}
catch( itk::ExceptionObject & excp )
{
std::cerr << excp << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}