Examples/SpatialObjects/ImageSpatialObject.cxx

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 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
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 *  distributed under the License is distributed on an "AS IS" BASIS,
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 *  See the License for the specific language governing permissions and
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// Software Guide : BeginLatex
//
// \index{itk::ImageSpatialObject}
//
// An \doxygen{ImageSpatialObject} contains an \doxygen{Image} but adds the
// notion of spatial transformations and parent-child hierarchy. Let's begin
// the next example by including the appropriate header file.
//
// Software Guide : EndLatex
 
#include "itkImageRegionIterator.h"
 
// Software Guide : BeginCodeSnippet
#include "itkImageSpatialObject.h"
// Software Guide : EndCodeSnippet
 
int
main(int, char *[])
{
  // Software Guide : BeginLatex
  //
  //  We first create a simple 2D image of size 10 by 10 pixels.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using Image = itk::Image<short, 2>;
  auto                      image = Image::New();
  constexpr Image::SizeType size = { { 10, 10 } };
  Image::RegionType         region;
  region.SetSize(size);
  image->SetRegions(region);
  image->Allocate();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  //  Next we fill the image with increasing values.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using Iterator = itk::ImageRegionIterator<Image>;
  Iterator it(image, region);
  short    pixelValue = 0;
 
  for (it.GoToBegin(); !it.IsAtEnd(); ++it, ++pixelValue)
  {
    it.Set(pixelValue);
  }
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // We can now define the \code{ImageSpatialObject} which is templated over
  // the dimension and the pixel type of the image.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using ImageSpatialObject = itk::ImageSpatialObject<2, short>;
  auto imageSO = ImageSpatialObject::New();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // Then we set the itkImage to the \code{ImageSpatialObject} by using the
  // \code{SetImage()} function.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  imageSO->SetImage(image);
  imageSO->Update();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // At this point we can use \code{IsInsideInWorldSpace()},
  // \code{IsInsideInObjectSpace()}, \code{ValueAtInWorldSpace()},
  // \code{ValueAtInObjectSpace()}, \code{DerivativeAtInWorldSpace()},
  // and \code{DerivativeAtInObjectSpace()} functions inherent in
  // SpatialObjects. The \code{IsInsideInWorldSpace()} value can be
  // particularly useful when dealing with registration.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using Point = itk::Point<double, 2>;
  auto insidePoint = itk::MakeFilled<Point>(9);
 
  if (imageSO->IsInsideInWorldSpace(insidePoint))
  {
    std::cout << insidePoint << " is inside the image." << std::endl;
  }
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  //  The \code{ValueAtInWorldSpace()} returns the value of the closest pixel,
  //  i.e no interpolation, to a given physical point.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  double returnedValue;
  imageSO->ValueAtInWorldSpace(insidePoint, returnedValue);
  std::cout << "ValueAt(" << insidePoint << ") = " << returnedValue
            << std::endl;
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  //  The derivative at a specified position in space can be computed using
  //  the \code{DerivativeAtInWorldSpace()} function. The first argument is
  //  the point in physical coordinates where we are evaluating the
  //  derivatives. The second argument is the order of the derivation, and the
  //  third argument is the result expressed as a \doxygen{Vector}.
  //  Derivatives are computed iteratively using finite differences and, like
  //  the \code{ValueAtInWorldSpace()}, no interpolator is used.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  ImageSpatialObject::DerivativeVectorType returnedDerivative;
  imageSO->DerivativeAtInWorldSpace(insidePoint, 1, returnedDerivative);
  std::cout << "First derivative at " << insidePoint;
  std::cout << " = " << returnedDerivative << std::endl;
  // Software Guide : EndCodeSnippet
 
  return EXIT_SUCCESS;
}