#include <itkLevelSetMotionRegistrationFilter.h>
Inheritance diagram for itk::LevelSetMotionRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >:
LevelSetMotionFilter implements a deformable registration algorithm that aligns a fixed and a moving image under level set motion. The equations of motion are similar to those of the DemonsRegistrationFilter. The main differences are: (1) Gradients of the moving image are calculated on a smoothed image while intensity difference are measured on the original images (2) Magnitude of the motion vector is a function of the differences in intensity between the fixed and moving pixel. An adaptive timestep is calculated based on the maximum motion vector over the entire field to ensure stability. The timestep also implictly converts the motion vector measured in units of intensity to a vector measured in physical units. Demons, on the other hand, defines its motion vectors as function of both the intensity differences and gradient magnitude at each respective pixel. Consider two separate pixels with the same intensity differences between the corresponding fixed and moving pixel pairs. In demons, the motion vector of the pixel over a low gradient region will be larger than the motion vector of the pixel over a large gradient region. This leads to an unstable vector field. In the levelset approach, the motion vectors will be proportional to the gradients, scaled by the maximum gradient over the entire field. The pixel with at the lower gradient position will more less than the pixel at the higher gradient position. (3) Gradients are calculated using minmod finite difference instead of using central differences.
A deformation field is represented as a image whose pixel type is some vector type with at least N elements, where N is the dimension of the fixed image. The vector type must support element access via operator []. It is assumed that the vector elements behave like floating point scalars.
This class is templated over the fixed image type, moving image type and the deformation field type.
The input fixed and moving images are set via methods SetFixedImage and SetMovingImage respectively. An initial deformation field maybe set via SetInitialDeformationField or SetInput. If no initial field is set, a zero field is used as the initial condition.
The algorithm has one parameters: the number of iteration to be performed.
The output deformation field can be obtained via methods GetOutput or GetDeformationField.
This class make use of the finite difference solver hierarchy. Update for each iteration is computed in LevelSetMotionFunction.
Definition at line 89 of file itkLevelSetMotionRegistrationFilter.h.
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 99 of file itkLevelSetMotionRegistrationFilter.h. |
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 123 of file itkLevelSetMotionRegistrationFilter.h. |
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Deformation field type. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 121 of file itkLevelSetMotionRegistrationFilter.h. |
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FiniteDifferenceFunction type. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 127 of file itkLevelSetMotionRegistrationFilter.h. |
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 113 of file itkLevelSetMotionRegistrationFilter.h. |
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FixedImage image type. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 112 of file itkLevelSetMotionRegistrationFilter.h. |
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LevelSetMotionFilterFunction type. Definition at line 131 of file itkLevelSetMotionRegistrationFilter.h. |
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 117 of file itkLevelSetMotionRegistrationFilter.h. |
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MovingImage image type. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 116 of file itkLevelSetMotionRegistrationFilter.h. |
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 98 of file itkLevelSetMotionRegistrationFilter.h. |
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Standard class typedefs. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 95 of file itkLevelSetMotionRegistrationFilter.h. Referenced by itk::LevelSetMotionRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >::~LevelSetMotionRegistrationFilter(). |
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Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. Definition at line 97 of file itkLevelSetMotionRegistrationFilter.h. |
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Inherit types from superclass. Reimplemented from itk::DenseFiniteDifferenceImageFilter< TDeformationField, TDeformationField >. Definition at line 109 of file itkLevelSetMotionRegistrationFilter.h. Referenced by itk::LevelSetMotionRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >::~LevelSetMotionRegistrationFilter(). |
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Apply update. Reimplemented from itk::DenseFiniteDifferenceImageFilter< TDeformationField, TDeformationField >. |
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Set/Get the parameter alpha. Alpha is added to the calculated gradient magnitude prior to normalizing the gradient to protect against numerical instability as the gradient magnitude approaches zero. This should be set as a small fraction of the intensity dynamic range, for instance 0.04%. Default is the absolute (not percentage) value of 0.1. |
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Set/Get the threshold below which the gradient magnitude is considered the zero vector. Default is 1e-9. |
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Set/Get the standard deviation used for smoothing the moving image prior to calculating gradients. The standard deviation is measured in physical units (for instance mm). Note that this smoothing value is not to be confused with the PDEDeformableRegistrationFilter::SetStandardDeviations() method. The method in PDEDeformableRegistrationFilter is for setting the smoothing parameters for regularizing the deformation field between interations. Those smoothing parameters are set in pixel units not physical units. Deformation field smoothing is not done by default in LevelSetMotionRegistration. This smoothing parameter is to condition the gradient calculation and parameter is specified in physical units. |
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Set/Get the threshold below which the absolute difference of intensity yields a match. When the intensities match between a moving and fixed image pixel, the update vector (for that iteration) will be the zero vector. Default is 0.001. |
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Get the metric value. The metric value is the mean square difference in intensity between the fixed image and transforming moving image computed over the the overlapping region between the two images. This is value is only available for the previous iteration and NOT the current iteration. |
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Run-time type information (and related methods). Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. |
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This method returns true when the current iterative solution of the equation has met the criteria to stop solving. This version calls the superclass' version but also Halts if the RMSChange is zero. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. |
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Initialize the state of filter and equation before each iteration. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. |
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Method for creation through the object factory. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. |
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Methods invoked by Print() to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes. Reimplemented from itk::PDEDeformableRegistrationFilter< TFixedImage, TMovingImage, TDeformationField >. |
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Set/Get the parameter alpha. Alpha is added to the calculated gradient magnitude prior to normalizing the gradient to protect against numerical instability as the gradient magnitude approaches zero. This should be set as a small fraction of the intensity dynamic range, for instance 0.04%. Default is the absolute (not percentage) value of 0.1. |
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Set/Get the threshold below which the gradient magnitude is considered the zero vector. Default is 1e-9. |
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Set/Get the standard deviation used for smoothing the moving image prior to calculating gradients. The standard deviation is measured in physical units (for instance mm). Note that this smoothing value is not to be confused with the PDEDeformableRegistrationFilter::SetStandardDeviations() method. The method in PDEDeformableRegistrationFilter is for setting the smoothing parameters for regularizing the deformation field between interations. Those smoothing parameters are set in pixel units not physical units. Deformation field smoothing is not done by default in LevelSetMotionRegistration. This smoothing parameter is to condition the gradient calculation and parameter is specified in physical units. |
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Set/Get the threshold below which the absolute difference of intensity yields a match. When the intensities match between a moving and fixed image pixel, the update vector (for that iteration) will be the zero vector. Default is 0.001. |
1.3.5 written by Dimitri van Heesch,
© 1997-2000