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/*=========================================================================
*
* Copyright NumFOCUS
*
* 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
*
* https://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 itkVersorTransformOptimizer_h
#define itkVersorTransformOptimizer_h
#include "itkRegularStepGradientDescentOptimizer.h"
#include "itkVersor.h"
#include "ITKOptimizersExport.h"
namespace itk
{
/** \class VersorTransformOptimizer
* \brief Implement a gradient descent optimizer
*
* VersorTransformOptimizer is a variant of the
* gradient descent optimizer implemented in
* RegularStepGradientDescentOptimizer.
*
* Versors are not in a vector space, for that reason,
* the classical gradient descent algorithm has to be
* modified in order to be applicable to Versors (unit
* quaternions) that form the group SO(3).
*
* The Versor space has only three degrees of freedom,
* even though Versors are represented using four values.
*
* This optimizer assumes that the CostFunction to be
* optimized has an itk::Versor as parameters.
*
* \sa RegularStepGradientDescentOptimizer
* \sa Versor
* \sa VersorTransform
*
* \ingroup Numerics Optimizers
* \ingroup ITKOptimizers
*/
class ITKOptimizers_EXPORT VersorTransformOptimizer : public RegularStepGradientDescentBaseOptimizer
{
public:
ITK_DISALLOW_COPY_AND_MOVE(VersorTransformOptimizer);
/** Standard class type aliases. */
using Self = VersorTransformOptimizer;
using Superclass = RegularStepGradientDescentBaseOptimizer;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** \see LightObject::GetNameOfClass() */
itkOverrideGetNameOfClassMacro(VersorTransformOptimizer);
/** Versor Type */
using VersorType = Versor<double>;
using VectorType = VersorType::VectorType;
/** Advance one step following the gradient direction. */
void
StepAlongGradient(double factor, const DerivativeType & transformedGradient) override;
protected:
VersorTransformOptimizer() = default;
~VersorTransformOptimizer() override = default;
};
} // end namespace itk
#endif
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