/*========================================================================= Program: Insight Segmentation & Registration Toolkit Module: $RCSfile: PointSetWithVectors.cxx,v $ Language: C++ Date: $Date: 2009-04-06 00:05:54 $ Version: $Revision: 1.20 $ Copyright (c) Insight Software Consortium. All rights reserved. See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. This software is distributed WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the above copyright notices for more information. =========================================================================*/ #if defined(_MSC_VER) #pragma warning ( disable : 4786 ) #endif // Software Guide : BeginLatex // // This example illustrates how a point set can be parameterized to manage a // particular pixel type. It is quite common to associate vector values with // points for producing geometric representations. The following code shows // how vector values can be used as pixel type on the PointSet class. The // \doxygen{Vector} class is used here as the pixel type. This class is // appropriate for representing the relative position between two points. It // could then be used to manage displacements, for example. // // \index{itk::PointSet!Vector pixels} // // In order to use the vector class it is necessary to include its header file // along with the header of the point set. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet #include "itkVector.h" #include "itkPointSet.h" // Software Guide : EndCodeSnippet int main(int, char *[]) { // Software Guide : BeginLatex // // \itkpiccaption[PointSet with Vectors as PixelType]{Vectors as PixelType.\label{fig:PointSetWithVectors}} // \parpic(6cm,4cm)[r]{\includegraphics[width=4cm]{PointSetWithVectors.eps}} // // The Vector class is templated over the type used to represent // the spatial coordinates and over the space dimension. Since the // PixelType is independent of the PointType, we are free to select any // dimension for the vectors to be used as pixel type. However, for the // sake of producing an interesting example, we will use vectors that // represent displacements of the points in the PointSet. Those vectors // are then selected to be of the same dimension as the PointSet. // // \index{itk::Vector!itk::PointSet} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet const unsigned int Dimension = 3; typedef itk::Vector< float, Dimension > PixelType; // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Then we use the PixelType (which are actually Vectors) to instantiate the // PointSet type and subsequently create a PointSet object. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef itk::PointSet< PixelType, Dimension > PointSetType; PointSetType::Pointer pointSet = PointSetType::New(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The following code is generating a sphere and assigning vector values // to the points. The components of the vectors in this example are // computed to represent the tangents to the circle as shown in // Figure~\ref{fig:PointSetWithVectors}. // // \index{itk::PointSet!SetPoint()} // \index{itk::PointSet!SetPointData()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet PointSetType::PixelType tangent; PointSetType::PointType point; unsigned int pointId = 0; const double radius = 300.0; for(unsigned int i=0; i<360; i++) { const double angle = i * vnl_math::pi / 180.0; point[0] = radius * vcl_sin( angle ); point[1] = radius * vcl_cos( angle ); point[2] = 1.0; // flat on the Z plane tangent[0] = vcl_cos(angle); tangent[1] = -vcl_sin(angle); tangent[2] = 0.0; // flat on the Z plane pointSet->SetPoint( pointId, point ); pointSet->SetPointData( pointId, tangent ); pointId++; } // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // We can now visit all the points and use the vector on the pixel values to // apply a displacement on the points. This is along the spirit of what a // deformable model could do at each one of its iterations. // // \index{itk::PointSet!PointIterator} // \index{itk::PointSet!GetPoints()} // \index{itk::PointSet!GetPointData()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef PointSetType::PointDataContainer::ConstIterator PointDataIterator; PointDataIterator pixelIterator = pointSet->GetPointData()->Begin(); PointDataIterator pixelEnd = pointSet->GetPointData()->End(); typedef PointSetType::PointsContainer::Iterator PointIterator; PointIterator pointIterator = pointSet->GetPoints()->Begin(); PointIterator pointEnd = pointSet->GetPoints()->End(); while( pixelIterator != pixelEnd && pointIterator != pointEnd ) { pointIterator.Value() = pointIterator.Value() + pixelIterator.Value(); ++pixelIterator; ++pointIterator; } // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Note that the \code{ConstIterator} was used here instead of the normal // \code{Iterator} since the pixel values are only intended to be read and // not modified. ITK supports const-correctness at the API level. // // \index{ConstIterator} // \index{const-correctness} // // Software Guide : EndLatex // Software Guide : BeginLatex // // The \doxygen{Vector} class has overloaded the \code{+} operator with // the \doxygen{Point}. In other words, vectors can be added to points in // order to produce new points. This property is exploited in the center // of the loop in order to update the points positions with a single // statement. // // \index{itk::PointSet!PointIterator} // // We can finally visit all the points and print out the new values // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet pointIterator = pointSet->GetPoints()->Begin(); pointEnd = pointSet->GetPoints()->End(); while( pointIterator != pointEnd ) { std::cout << pointIterator.Value() << std::endl; ++pointIterator; } // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Note that \doxygen{Vector} is not the appropriate class for // representing normals to surfaces and gradients of functions. This is due // to the way in which vectors behave under affine transforms. ITK has a // specific class for representing normals and function gradients. This is // the \doxygen{CovariantVector} class. // // Software Guide : EndLatex return 0; }