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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 itkGeodesicActiveContourShapePriorLevelSetFunction_h
#define itkGeodesicActiveContourShapePriorLevelSetFunction_h
#include "itkShapePriorSegmentationLevelSetFunction.h"
namespace itk
{
/** \class GeodesicActiveContourShapePriorLevelSetFunction
*
* \brief This function is used in
* GeodesicActiveContourShapePriorSegmentationLevelSetFilter to
* segment structures in an image based on user supplied edge potential map and
* shape model.
*
* \par IMPORTANT
* The LevelSetFunction, SegmentationLevelSetFunction and
* ShapePriorSegmentationLevelSetFunction classes contain additional
* information necessary to gain full understanding of how to use
* this function.
*
* GeodesicActiveContourShapePriorLevelSetFunction is a subclass of the
* generic LevelSetFunction.
* It is used to segment structures in an image based on a user supplied
* edge potential map \f$ g(I) \f$, which
* has values close to zero in regions near edges (or high image gradient) and values
* close to one in regions with relatively constant intensity. Typically, the edge
* potential map is a function of the gradient, for example:
*
* \f[ g(I) = 1 / ( 1 + | (\nabla * G)(I)| ) \f]
* \f[ g(I) = \exp^{-|(\nabla * G)(I)|} \f]
*
* where \f$ I \f$ is image intensity and
* \f$ (\nabla * G) \f$ is the derivative of Gaussian operator.
*
* The edge potential image is set via the SetFeatureImage() method.
*
* In this function both the propagation term \f$ P(\mathbf{x}) \f$
* and the curvature spatial modifier term \f$ Z(\mathbf{x}) \f$ are taken directly
* from the edge potential image such that:
*
* \f[ P(\mathbf{x}) = g(\mathbf{x}) \f]
* \f[ Z(\mathbf{x}) = g(\mathbf{x}) \f]
*
* An advection term \f$ \mathbf{A}(\mathbf{x}) \f$ is constructed
* from the negative gradient of the edge potential image.
*
* \f[ \mathbf{A}(\mathbf{x}) = -\nabla g(\mathbf{x}) \f]
*
* This term behaves like a doublet attracting the contour to the edges.
*
* This class extends the basic LevelSetFunction with a shape prior term
* as developed in [1].
*
* \f$ \zeta( \phi^{*} - \phi) \f$
*
* where \f$ \phi^{*} \f$ is the signed distance function from a target shape
* and \f$ \zeta \f$ is a scalar constant.
*
* The target shape signed distance function is supplied through a
* ShapeSignedDistanceFunction object. Typically, the shape is a function
* of a set of parameters.
*
* \sa LevelSetFunction
* \sa SegmentationLevelSetFunction
* \sa ShapePriorSegmentationLevelSetFunction
* \sa ShapeSignedDistanceFunction
*
* \par REFERENCES
* \par
* [1] Leventon, M.E. et al. "Statistical Shape Influence in Geodesic Active Contours", CVPR 2000.
*
* \ingroup FiniteDifferenceFunctions
* \ingroup ITKLevelSets
*/
template <typename TImageType, typename TFeatureImageType = TImageType>
class ITK_TEMPLATE_EXPORT GeodesicActiveContourShapePriorLevelSetFunction
: public ShapePriorSegmentationLevelSetFunction<TImageType, TFeatureImageType>
{
public:
ITK_DISALLOW_COPY_AND_MOVE(GeodesicActiveContourShapePriorLevelSetFunction);
/** Standard class type aliases. */
using Self = GeodesicActiveContourShapePriorLevelSetFunction;
using Superclass = ShapePriorSegmentationLevelSetFunction<TImageType, TFeatureImageType>;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
using FeatureImageType = TFeatureImageType;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** \see LightObject::GetNameOfClass() */
itkOverrideGetNameOfClassMacro(GeodesicActiveContourShapePriorLevelSetFunction);
/** Extract some parameters from the superclass. */
using typename Superclass::ImageType;
using typename Superclass::NeighborhoodType;
using typename Superclass::ScalarValueType;
using typename Superclass::FeatureScalarType;
using typename Superclass::RadiusType;
using typename Superclass::FloatOffsetType;
using typename Superclass::VectorImageType;
using typename Superclass::GlobalDataStruct;
/** Extract some parameters from the superclass. */
static constexpr unsigned int ImageDimension = Superclass::ImageDimension;
/** Compute speed image from feature image. */
void
CalculateSpeedImage() override;
/** Compute the advection field from feature image. */
void
CalculateAdvectionImage() override;
/** The curvature speed is same as the propagation speed. */
ScalarValueType
CurvatureSpeed(const NeighborhoodType & neighborhood,
const FloatOffsetType & offset,
GlobalDataStruct * gd) const override
{
return this->PropagationSpeed(neighborhood, offset, gd);
}
/** Set/Get the sigma for the Gaussian kernel used to compute the gradient
* of the feature image needed for the advection term of the equation. */
void
SetDerivativeSigma(const double v)
{
m_DerivativeSigma = v;
}
double
GetDerivativeSigma()
{
return m_DerivativeSigma;
}
void
Initialize(const RadiusType & r) override
{
Superclass::Initialize(r);
this->SetAdvectionWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetPropagationWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetCurvatureWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetShapePriorWeight(NumericTraits<ScalarValueType>::OneValue());
}
protected:
GeodesicActiveContourShapePriorLevelSetFunction()
{
this->SetAdvectionWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetPropagationWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetCurvatureWeight(NumericTraits<ScalarValueType>::OneValue());
this->SetShapePriorWeight(NumericTraits<ScalarValueType>::OneValue());
m_DerivativeSigma = 1.0;
}
~GeodesicActiveContourShapePriorLevelSetFunction() override = default;
void
PrintSelf(std::ostream & os, Indent indent) const override;
private:
double m_DerivativeSigma{};
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
# include "itkGeodesicActiveContourShapePriorLevelSetFunction.hxx"
#endif
#endif
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