R/integrateVelocityField.R

In stnava/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

#' integrateVelocityField
#'
#' Integrate velocity field
#'
#' @param velocityField time-varying displacement field
#' @param lowerIntegrationBound Lower time bound for integration in [0, 1]
#' @param upperIntegrationBound Upper time bound for integration in [0, 1]
#' @param numberOfIntegrationSteps Number of integration steps used in the Runge-Kutta solution
#' @return integrated field
#'
#' @author NJ Tustison
#'
#' @examples
#' fi <- antsImageRead(getANTsRData("r16"))
#' mi <- antsImageRead(getANTsRData("r27"))
#' reg <- antsRegistration(fi, mi, "TV[2]")
#' velocityField <- antsImageRead(reg$velocityfield)
#' field <- integrateVelocityField(velocityField, 0.0, 1.0, 10)
#'
#' @export integrateVelocityField
integrateVelocityField <- function(
    velocityField,
    lowerIntegrationBound = 0.0,
    upperIntegrationBound = 1.0,
    numberOfIntegrationSteps = 10) {
  dimensionality <- velocityField@dimension - 1

  integratedField <- ANTsRCore::integrateVelocityField(
    dimensionality,
    velocityField,
    as.numeric(lowerIntegrationBound),
    as.numeric(upperIntegrationBound),
    as.numeric(numberOfIntegrationSteps)
  )
  return(integratedField)
}