ITK  4.2.0
Insight Segmentation and Registration Toolkit
itkKalmanLinearEstimator.h
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18 #ifndef __itkKalmanLinearEstimator_h
19 #define __itkKalmanLinearEstimator_h
20 
21 #include "itkMacro.h"
22 
23 #include "vnl/vnl_vector_fixed.h"
24 #include "vnl/vnl_matrix_fixed.h"
25 
26 namespace itk
27 {
41 template< class T, unsigned int VEstimatorDimension >
42 class ITK_EXPORT KalmanLinearEstimator
43 {
44 public:
47  itkStaticConstMacro(Dimension, unsigned int,
48  VEstimatorDimension);
49 
52  typedef vnl_vector_fixed< T, VEstimatorDimension > VectorType;
53 
56  typedef vnl_matrix_fixed< T, VEstimatorDimension, VEstimatorDimension > MatrixType;
57 
62  typedef T ValueType;
63 
68  void UpdateWithNewMeasure(const ValueType & newMeasure,
69  const VectorType & newPredictor);
70 
74  void ClearEstimation(void)
75  { m_Estimator = VectorType( T(0) ); }
76 
79  void ClearVariance(void)
80  {
81  m_Variance.set_identity();
82  }
83 
90  void SetVariance(const ValueType & var = 1.0)
91  {
92  m_Variance.set_identity();
93  m_Variance *= var;
94  }
96 
102  void SetVariance(const MatrixType & m)
103  { m_Variance = m; }
104 
107  const VectorType & GetEstimator(void) const
108  { return m_Estimator; }
109 
112  const MatrixType & GetVariance(void) const
113  { return m_Variance; }
114 private:
115 
120  void UpdateVariance(const VectorType &);
121 
125 
133 };
134 
135 template< class T, unsigned int VEstimatorDimension >
136 void
139  const VectorType & newPredictor)
140 {
141  ValueType measurePrediction = dot_product(newPredictor, m_Estimator);
142 
143  ValueType errorMeasurePrediction = newMeasure - measurePrediction;
144 
145  VectorType Corrector = m_Variance * newPredictor;
146 
147  for ( unsigned int j = 0; j < VEstimatorDimension; j++ )
148  {
149  m_Estimator(j) += Corrector(j) * errorMeasurePrediction;
150  }
151 
152  UpdateVariance(newPredictor);
153 }
154 
155 template< class T, unsigned int VEstimatorDimension >
156 void
158 ::UpdateVariance(const VectorType & newPredictor)
159 {
160  VectorType aux = m_Variance * newPredictor;
161 
162  ValueType denominator = 1.0 / ( 1.0 + dot_product(aux, newPredictor) );
163 
164  for ( unsigned int col = 0; col < VEstimatorDimension; col++ )
165  {
166  for ( unsigned int row = 0; row < VEstimatorDimension; row++ )
167  {
168  m_Variance(col, row) -= aux(col) * aux(row) * denominator;
169  }
170  }
171 }
172 } // end namespace itk
173 
174 #endif
175