itkNormalVectorDiffusionFunction.h

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/*=========================================================================
 *
 *  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.
 *
 *=========================================================================*/
#ifndef __itkNormalVectorDiffusionFunction_h
#define __itkNormalVectorDiffusionFunction_h

#include "itkNormalVectorFunctionBase.h"
#include "itkNumericTraits.h"
#include <cmath>

namespace itk
{
template< typename TSparseImageType >
class NormalVectorDiffusionFunction:
  public NormalVectorFunctionBase< TSparseImageType >
{
public:
  typedef NormalVectorDiffusionFunction                Self;
  typedef NormalVectorFunctionBase< TSparseImageType > Superclass;
  typedef SmartPointer< Self >                         Pointer;
  typedef SmartPointer< const Self >                   ConstPointer;

  itkTypeMacro(NormalVectorDiffusionFunction, NormalVectorFunctionBase);

  itkStaticConstMacro(ImageDimension, unsigned int, Superclass::ImageDimension);

  itkNewMacro(Self);

  typedef typename Superclass::TimeStepType           TimeStepType;
  typedef typename Superclass::RadiusType             RadiusType;
  typedef typename Superclass::NeighborhoodType       NeighborhoodType;
  typedef typename Superclass::NeighborhoodScalesType NeighborhoodScalesType;
  typedef typename Superclass::FloatOffsetType        FloatOffsetType;
  typedef typename Superclass::IndexType              IndexType;
  typedef typename Superclass::SparseImageType        SparseImageType;
  typedef typename Superclass::NodeType               NodeType;
  typedef typename Superclass::NodeValueType          NodeValueType;
  typedef typename Superclass::NormalVectorType       NormalVectorType;

  void SetNormalProcessType(int npt)
  { m_NormalProcessType = npt; }

  int GetNormalProcessType() const
  { return m_NormalProcessType; }

  void SetConductanceParameter(NodeValueType cp)
  {
    m_ConductanceParameter = cp + static_cast< NodeValueType >( 0.001 );
    // we add a minimum conductance to avoid divide by zero
    // can make this a parameter.
    m_FluxStopConstant = static_cast< NodeValueType >
                         ( -1.0 / ( m_ConductanceParameter * m_ConductanceParameter ) );
  }

  NodeValueType GetConductanceParameter() const
  { return m_ConductanceParameter; }

  NodeValueType GetFluxStopConstant() const
  { return m_FluxStopConstant; }

  virtual void PrecomputeSparseUpdate(NeighborhoodType & it) const;

  virtual NormalVectorType ComputeSparseUpdate(NeighborhoodType & neighborhood,
                                               void *globalData,
                                               const FloatOffsetType & offset) const;

protected:
  NormalVectorDiffusionFunction();
  ~NormalVectorDiffusionFunction() {}
  void PrintSelf(std::ostream & os, Indent indent) const;

  NodeValueType FluxStopFunction(const NodeValueType v) const
  {
    // the slow exp function could be replaced with a lookup table
    if ( v <= 0.0 ) { return NumericTraits< NodeValueType >::One; }
    else { return static_cast< NodeValueType >( std::exp(m_FluxStopConstant * v) ); }
  }

private:
  NodeValueType m_ConductanceParameter;

  NodeValueType m_FluxStopConstant;

  int m_NormalProcessType;

  NormalVectorDiffusionFunction(const Self &); //purposely not implemented
  void operator=(const Self &);                //purposely not implemented
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkNormalVectorDiffusionFunction.hxx"
#endif

#endif