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/*=========================================================================
*
* Copyright UMC Utrecht and contributors
*
* 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 _itkWeightedCombinationTransform_hxx
#define _itkWeightedCombinationTransform_hxx
#include "itkWeightedCombinationTransform.h"
#include <numeric> // For iota.
namespace itk
{
/**
* ********************* Constructor ****************************
*/
template <class TScalarType, unsigned int NInputDimensions, unsigned int NOutputDimensions>
WeightedCombinationTransform<TScalarType, NInputDimensions, NOutputDimensions>::WeightedCombinationTransform()
: Superclass(OutputSpaceDimension)
{
this->m_SumOfWeights = 1.0;
this->m_NormalizeWeights = false;
this->m_HasNonZeroSpatialHessian = true;
this->m_HasNonZeroJacobianOfSpatialHessian = true;
} // end Constructor
/**
* ************************ SetParameters ***********************
*/
template <class TScalarType, unsigned int NInputDimensions, unsigned int NOutputDimensions>
void
WeightedCombinationTransform<TScalarType, NInputDimensions, NOutputDimensions>::SetParameters(
const ParametersType & param)
{
if (param.GetSize() != this->m_TransformContainer.size())
{
itkExceptionMacro("Number of parameters does not match the number of transforms set in the transform container.");
}
// this->m_Jacobian.set_size( OutputSpaceDimension, param.GetSize() );
this->m_Parameters = param;
this->m_SumOfWeights = param.sum();
if (this->m_SumOfWeights < 1e-10 && this->m_NormalizeWeights)
{
itkExceptionMacro("Sum of weights for WeightedCombinationTransform is smaller than 0.");
}
// Precompute the nonzerojacobianindices vector
const NumberOfParametersType nrParams = param.GetSize();
if (nrParams != this->m_NonZeroJacobianIndices.size())
{
this->m_NonZeroJacobianIndices.resize(nrParams);
std::iota(m_NonZeroJacobianIndices.begin(), m_NonZeroJacobianIndices.end(), 0u);
}
this->Modified();
} // end SetParameters()
/**
* ********************* TransformPoint ****************************
*/
template <class TScalarType, unsigned int NInputDimensions, unsigned int NOutputDimensions>
auto
WeightedCombinationTransform<TScalarType, NInputDimensions, NOutputDimensions>::TransformPoint(
const InputPointType & inputPoint) const -> OutputPointType
{
OutputPointType opp{};
OutputPointType tempopp;
const TransformContainerType & tc = this->m_TransformContainer;
const unsigned int N = tc.size();
const ParametersType & param = this->m_Parameters;
/** Calculate sum_i w_i T_i(x) */
for (unsigned int i = 0; i < N; ++i)
{
tempopp = tc[i]->TransformPoint(inputPoint);
const double w = param[i];
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
opp[d] += w * tempopp[d];
}
}
if (this->m_NormalizeWeights)
{
/** T(x) = \sum_i w_i T_i(x) / sum_i w_i */
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
opp[d] /= this->m_SumOfWeights;
}
}
else
{
/** T(x) = (1 - \sum_i w_i ) x + \sum_i w_i T_i(x) */
const double factor = 1.0 - this->m_SumOfWeights;
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
opp[d] += factor * inputPoint[d];
}
}
return opp;
} // end TransformPoint
/**
* ********************* GetJacobian ****************************
*/
template <class TScalarType, unsigned int NInputDimensions, unsigned int NOutputDimensions>
void
WeightedCombinationTransform<TScalarType, NInputDimensions, NOutputDimensions>::GetJacobian(
const InputPointType & inputPoint,
JacobianType & jac,
NonZeroJacobianIndicesType & nzji) const
{
OutputPointType tempopp;
const TransformContainerType & tc = this->m_TransformContainer;
const unsigned int N = tc.size();
const ParametersType & param = this->m_Parameters;
jac.set_size(OutputSpaceDimension, N);
/** This transform has only nonzero jacobians. */
nzji = this->m_NonZeroJacobianIndices;
if (this->m_NormalizeWeights)
{
/** dT/dmu_i = ( T_i(x) - T(x) ) / ( \sum_i w_i ) */
OutputPointType opp{};
for (unsigned int i = 0; i < N; ++i)
{
tempopp = tc[i]->TransformPoint(inputPoint);
const double w = param[i];
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
opp[d] += w * tempopp[d];
jac(d, i) = tempopp[d];
}
}
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
opp[d] /= this->m_SumOfWeights;
}
for (unsigned int i = 0; i < N; ++i)
{
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
jac(d, i) = (jac(d, i) - opp[d]) / this->m_SumOfWeights;
}
}
}
else
{
/** dT/dmu_i = T_i(x) - x */
for (unsigned int i = 0; i < N; ++i)
{
tempopp = tc[i]->TransformPoint(inputPoint);
for (unsigned int d = 0; d < OutputSpaceDimension; ++d)
{
jac(d, i) = tempopp[d] - inputPoint[d];
}
}
}
} // end GetJacobian()
} // end namespace itk
#endif
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