itkQuadEdgeMeshDiscretePrincipalCurvaturesEstimator.h

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkQuadEdgeMeshDiscretePrincipalCurvaturesEstimator.h,v $
  Language:  C++
  Date:      $Date: 2010-01-14 19:03:21 $
  Version:   $Revision: 1.3 $

  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.

=========================================================================*/

#ifndef __itkQuadEdgeMeshDiscretePrincipalCurvaturesEstimator_h
#define __itkQuadEdgeMeshDiscretePrincipalCurvaturesEstimator_h

#include "itkQuadEdgeMeshDiscreteCurvatureEstimator.h"
#include "itkQuadEdgeMeshParamMatrixCoefficients.h"

namespace itk
{
template< class TInputMesh, class TOutputMesh >
class QuadEdgeMeshDiscretePrincipalCurvaturesEstimator :
  public QuadEdgeMeshDiscreteCurvatureEstimator< TInputMesh, TOutputMesh >
{
public:
  typedef QuadEdgeMeshDiscretePrincipalCurvaturesEstimator      Self;
  typedef SmartPointer< Self >                                  Pointer;
  typedef SmartPointer< const Self >                            ConstPointer;
  typedef QuadEdgeMeshDiscreteCurvatureEstimator< 
    TInputMesh, TOutputMesh >                                   Superclass;

  typedef typename Superclass::InputMeshType                    InputMeshType;
  typedef typename Superclass::InputMeshPointer                 InputMeshPointer;
  typedef typename Superclass::OutputMeshType                   OutputMeshType;
  typedef typename Superclass::OutputMeshPointer                OutputMeshPointer;
  typedef typename Superclass::OutputPointsContainerPointer     OutputPointsContainerPointer;
  typedef typename Superclass::OutputPointsContainerIterator    OutputPointsContainerIterator;
  typedef typename Superclass::OutputPointType                  OutputPointType;
  typedef typename Superclass::OutputVectorType                 OutputVectorType;
  typedef typename Superclass::OutputCoordType                  OutputCoordType;
  typedef typename Superclass::OutputPointIdentifier            OutputPointIdentifier;
  typedef typename Superclass::OutputCellIdentifier             OutputCellIdentifier;
  typedef typename Superclass::OutputQEType                     OutputQEType;
  typedef typename Superclass::OutputMeshTraits                 OutputMeshTraits;
  typedef typename Superclass::OutputCurvatureType              OutputCurvatureType;
  
  typedef typename Superclass::TriangleType                     TriangleType;
    
  itkTypeMacro( QuadEdgeMeshDiscretePrincipalCurvaturesEstimator, QuadEdgeMeshDiscreteCurvatureEstimator );

  typedef ConformalMatrixCoefficients< OutputMeshType >         CoefficientType;

protected:
  QuadEdgeMeshDiscretePrincipalCurvaturesEstimator() :
    m_Gaussian( 0.0 ), m_Mean( 0.0 ){}
  ~QuadEdgeMeshDiscretePrincipalCurvaturesEstimator() {}

  OutputCurvatureType               m_Gaussian;
  OutputCurvatureType               m_Mean;

  void ComputeMeanAndGaussianCurvatures( const OutputPointType& iP )
    {
    OutputMeshPointer output = this->GetOutput();

    OutputQEType* qe = iP.GetEdge( );
    m_Mean = 0.;
    m_Gaussian = 0.;

    if( qe != 0 )
      {
      OutputVectorType Laplace;
      Laplace.Fill( 0. );

      OutputQEType* qe_it = qe;

      OutputCurvatureType area( 0. ), sum_theta( 0. );

      if( qe_it != qe_it->GetOnext() )
        {
        qe_it = qe;
        OutputQEType* qe_it2;

        OutputPointType q0, q1;
        OutputVectorType face_normal;

        OutputVectorType normal;
        normal.Fill( 0. );

        OutputCurvatureType temp_area;
        OutputCoordType temp_coeff;

        CoefficientType coefficent;

        do
          {
          qe_it2 = qe_it->GetOnext();
          q0 = output->GetPoint( qe_it->GetDestination() );
          q1 = output->GetPoint( qe_it2->GetDestination() );

          temp_coeff = coefficent( output, qe_it );
          Laplace += temp_coeff * ( iP - q0 );

          // Compute Angle;
          sum_theta += static_cast< OutputCurvatureType >(
            TriangleType::ComputeAngle( q0, iP, q1 ) );

          temp_area = ComputeMixedArea( qe_it, qe_it2 );
          area += temp_area;

          face_normal = TriangleType::ComputeNormal( q0, iP, q1 );
          normal += face_normal;

          qe_it = qe_it2;
          } while( qe_it != qe );

        if( area > 1e-10 )
          {
          area = 1. / area;
          Laplace *= 0.25 * area;
          m_Mean = Laplace * normal;
          m_Gaussian = ( 2. * vnl_math::pi - sum_theta ) * area;
          }
        }
      }
    }

  virtual OutputCurvatureType ComputeDelta( )
    {
    return  vnl_math_max( 0., m_Mean * m_Mean - m_Gaussian );
    }

private:
  QuadEdgeMeshDiscretePrincipalCurvaturesEstimator( const Self& ); // purposely not implemented
  void operator = ( const Self& ); // purposely not implemented

};

}

#endif