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itkBSplineKernelFunction.h

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00001 /*=========================================================================
00002 
00003   Program:   Insight Segmentation & Registration Toolkit
00004   Module:    $RCSfile: itkBSplineKernelFunction.h,v $
00005   Language:  C++
00006   Date:      $Date: 2006/03/18 20:13:35 $
00007   Version:   $Revision: 1.7 $
00008 
00009   Copyright (c) Insight Software Consortium. All rights reserved.
00010   See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
00011 
00012      This software is distributed WITHOUT ANY WARRANTY; without even 
00013      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
00014      PURPOSE.  See the above copyright notices for more information.
00015 
00016 =========================================================================*/
00017 #ifndef __itkBSplineKernelFunction_h
00018 #define __itkBSplineKernelFunction_h
00019 
00020 #include "itkKernelFunction.h"
00021 #include "vnl/vnl_math.h"
00022 
00023 namespace itk
00024 {
00025 
00041 template <unsigned int VSplineOrder = 3>
00042 class ITK_EXPORT BSplineKernelFunction : public KernelFunction
00043 {
00044 public:
00046   typedef BSplineKernelFunction Self;
00047   typedef KernelFunction        Superclass;
00048   typedef SmartPointer<Self>    Pointer;
00049 
00051   itkNewMacro(Self); 
00052 
00054   itkTypeMacro(BSplineKernelFunction, KernelFunction); 
00055 
00057   itkStaticConstMacro(SplineOrder, unsigned int, VSplineOrder);
00058 
00060   inline double Evaluate( const double & u ) const
00061     {
00062     return this->Evaluate( Dispatch<VSplineOrder>(), u );
00063     }
00064 
00065 protected:
00066   BSplineKernelFunction(){};
00067   ~BSplineKernelFunction(){};
00068   void PrintSelf(std::ostream& os, Indent indent) const
00069     { 
00070     Superclass::PrintSelf( os, indent ); 
00071     os << indent  << "Spline Order: " << SplineOrder << std::endl;
00072     }  
00073 
00074 private:
00075   BSplineKernelFunction(const Self&); //purposely not implemented
00076   void operator=(const Self&); //purposely not implemented
00077 
00079   struct DispatchBase {};
00080   template<unsigned int>
00081   struct Dispatch : DispatchBase {};
00082 
00084   inline double Evaluate (const Dispatch<0>&, const double & u) const
00085     {
00086 
00087     double absValue = vnl_math_abs( u );
00088 
00089     if ( absValue  < 0.5 )
00090       {
00091       return 1.0;
00092       }
00093     else if ( absValue == 0.5 )
00094       {
00095       return 0.5;
00096       }
00097     else
00098       {
00099       return 0.0;
00100       }
00101 
00102     }
00103 
00105   inline double Evaluate ( const Dispatch<1>&, const double& u) const
00106     {
00107 
00108     double absValue = vnl_math_abs( u );
00109 
00110     if ( absValue  < 1.0 )
00111       {
00112       return 1.0 - absValue;
00113       }
00114     else
00115       {
00116       return 0.0;
00117       }
00118 
00119     }
00120 
00122   inline double Evaluate ( const Dispatch<2>&, const double& u) const
00123     {
00124 
00125     double absValue = vnl_math_abs( u );
00126 
00127     if ( absValue  < 0.5 )
00128       {
00129       return 0.75 - vnl_math_sqr( absValue );
00130       }
00131     else if ( absValue < 1.5 )
00132       {
00133       return ( 9.0 - 12.0 * absValue + 4.0 * vnl_math_sqr( absValue ) ) / 8.0; 
00134       }
00135     else
00136       {
00137       return 0.0;
00138       }
00139 
00140     }
00141 
00143   inline double Evaluate ( const Dispatch<3>&, const double& u) const
00144     {
00145 
00146     double absValue = vnl_math_abs( u );
00147     double sqrValue = vnl_math_sqr( u );
00148 
00149     if ( absValue  < 1.0 )
00150       {
00151       return ( 4.0 - 6.0 * sqrValue + 3.0 * sqrValue * absValue ) / 6.0;
00152       }
00153     else if ( absValue < 2.0 )
00154       {
00155       return ( 8.0 - 12 * absValue + 6.0 * sqrValue - 
00156                                             sqrValue * absValue ) / 6.0;
00157       }
00158     else
00159       {
00160       return 0.0;
00161       }
00162 
00163     }
00164 
00166   inline double Evaluate ( const DispatchBase&, const double&) const
00167     {
00168     itkExceptionMacro("Evaluate not implemented for spline\
00169                                                       order " << SplineOrder);
00170     return 0.0; // This is to avoid compiler warning about missing 
00171                 // return statement.  It should never be evaluated.
00172     }
00174 
00175 };
00176 
00177 
00178 } // end namespace itk
00179 
00180 #endif
00181 

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