fitTransformToPairedPoints — fitTransformToPairedPoints • ANTsR

Estimate a transform using paired point sets. An ANTsR transform is returned.

fitTransformToPairedPoints(
  movingPoints,
  fixedPoints,
  transformType = "affine",
  regularization = 1e-06,
  domainImage = NULL,
  numberOfFittingLevels = 4,
  meshSize = 1,
  splineOrder = 3,
  enforceStationaryBoundary = TRUE,
  displacementWeights = NULL,
  numberOfCompositions = 10,
  compositionStepSize = 0.5,
  sigma = 0,
  convergenceThreshold = 1e-06,
  numberOfTimeSteps = 2,
  numberOfIntegrationSteps = 100,
  rasterizePoints = FALSE,
  verbose = FALSE
)

Arguments

movingPoints: Moving points specified in physical space as a n x d matrix where n is the number of points and d is the dimensionality.
fixedPoints: Fixed points specified in physical space as a n x d matrix where n is the number of points and d is the dimensionality.
transformType: 'rigid', 'similarity', 'affine', 'bspline', 'tps', 'diffeo', 'syn', 'tv', or 'time-varying'.
regularization: Ridge penalty in [0,1] for linear transforms.
domainImage: Defines physical domain of the B-spline transform. Must be defined for nonlinear transforms.
numberOfFittingLevels: Integer specifying the number of fitting levels for the B-spline interpolation of the displacement field.
meshSize: Defines the mesh size at the initial fitting level for the B-spline interpolation of the displacement field.
splineOrder: Spline order of the B-spline displacement field.
enforceStationaryBoundary: Ensure no displacements on the image boundary (B-spline only).
displacementWeights: Defines the individual weighting of the corresponding scattered data value. Default = None meaning all displacements are weighted the same.
numberOfCompositions: Total number of compositions for the diffeomorphic transform.
compositionStepSize: Scalar multiplication factor of the weighting of the update field for the diffeomorphic transforms.
sigma: Gaussian smoothing standard deviation of the update field (in mm).
convergenceThreshold: Composition-based convergence parameter for the diffeomorphic transforms using a window size of 10 values.
numberOfTimeSteps: Time-varying velocity field parameter.
numberOfIntegrationSteps: Number of steps used for integrating the velocity field.
rasterizePoints: Use nearest neighbor rasterization of points for estimating update field (potential speed-up).
verbose: Print progress to the screen.

Value

object containing ANTsR transform, error, and scale (or displacement field)

Author

B Avants, N Tustison

Examples

fixed <- matrix(c(50, 50, 200, 50, 50, 200), ncol = 2, byrow = TRUE)
moving <- matrix(c(50, 50, 50, 200, 200, 200), ncol = 2, byrow = TRUE)

# Affine transform
xfrm <- fitTransformToPairedPoints(moving, fixed, transformType = "Affine", 
regularization = 0)
params <- getAntsrTransformParameters(xfrm)

# Rigid transform
xfrm <- fitTransformToPairedPoints(moving, fixed, transformType = "Rigid", 
regularization = 0)
params <- getAntsrTransformParameters(xfrm)

# Similarity transform
xfrm <- fitTransformToPairedPoints(moving, fixed, 
transformType = "Similarity", regularization = 0)
params <- getAntsrTransformParameters(xfrm)

# B-spline transform
domainImage <- antsImageRead(getANTsRData("r16"))
xfrm <- fitTransformToPairedPoints(moving, fixed, 
transformType = "Bspline", domainImage = domainImage, 
numberOfFittingLevels = 5)