fitBsplineDisplacementField: fitBsplineDisplacementField

In neuroconductor-devel/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

Description

Fit a b-spline object to a dense displacement field image and/or a set of points with associated displacements and smooths them using B-splines. The inverse can also be estimated.. This is basically a wrapper for the ITK filter https://itk.org/Doxygen/html/classitk_1_1DisplacementFieldToBSplineImageFilter.html which, in turn is a wrapper for the ITK filter used for the function ANTsR::fitBsplineObjectToScatteredData

Usage

fitBsplineDisplacementField(
  displacementField = NULL,
  displacementWeightImage = NULL,
  displacementOrigins = NULL,
  displacements = NULL,
  displacementWeights = NULL,
  origin = NULL,
  spacing = NULL,
  size = NULL,
  direction = NULL,
  numberOfFittingLevels = 4,
  meshSize = 1,
  splineOrder = 3,
  enforceStationaryBoundary = TRUE,
  estimateInverse = FALSE
)

Arguments

displacementField	input displacement field. Either this and/or the points must be specified.
displacementWeightImage	input image defining weighting of the voxelwise displacements in the displacementField. if NULL, defaults to identity weighting for each displacement. Default = NULL.
displacementOrigins	matrix (numberOfPoints x dimension) defining the origins of the input displacement points. Default = NULL.
displacements	matrix (numberOfPoints x dimension) defining the displacements of the input displacement points. Default = NULL.
displacementWeights	vector defining the individual weighting of the corresponding scattered data value. Default = NULL meaning all values are weighted the same.
origin	vector defining the physical origin of the B-spline displacement field. Must be specified if displacementField is not specified. Otherwise, the displacementField is used to define the domain parameters.
spacing	vector defining the physical spacing of the B-spline object. Defines the sampling rate in the parametric domain. Must be specified if displacementField is not specified. Otherwise, the displacementField is used to define the domain parameters.
size	vector defining the size (length) of the B-spline object. Note that the length of the B-spline object in dimension d is defined as parametricDomainSpacing[d] * (parametricDomainSize[d]-1). Must be specified if displacementField is not specified. Otherwise, the displacementField is used to define the domain parameters.
direction	matrix defining the orientation of the sampled B-spline object. Must be specified if displacementField is not specified. Otherwise, the displacementField is used to define the domain parameters.
numberOfFittingLevels	integer specifying the number of fitting levels.
meshSize	vector defining the mesh size at the initial fitting level.
splineOrder	spline order of the B-spline object. Default = 3.
enforceStationaryBoundary	ensure no displacements on the image boundary. Default = TRUE.
estimateInverse	estimate the inverse displacement field. Default = FALSE.

Value

ANTsR image.

Author(s)

NJ Tustison

Examples

# Perform 2-D fitting

points <- matrix( data = c( -50, -50 ), nrow = 1, byrow = TRUE )
deltas <- matrix( data = c( 10, 10 ), nrow = 1, byrow = TRUE )

bsplineField <- fitBsplineDisplacementField(
  displacementOrigins = points, displacements = deltas,
  origin = c( 0.0, 0.0 ), spacing = c( 1.0, 1.0 ), size = c( 100, 100 ),
  direction = matrix( data = c( -1, 0, 0, -1 ), nrow = 2, byrow = TRUE ),
  numberOfFittingLevels = 4, meshSize = c( 1, 1 ) )

neuroconductor-devel/ANTsR documentation built on April 1, 2021, 1:02 p.m.