R/retrieve_dist_to_utm.R

In vscholl/neonVstAop: Wrangling NEON Vegetation Data to Integrate with Airborne Remote Sensing Data

#' Using the coordinates of the point ids and trigonometry,
#' get precise locations of trees
#'@param dista numeric. distance between point id and tree stem
#'@param angle numeric. Azimut angle between point id and tree stem
#'@param xcord numeric. UTM East of the point ID
#'@param ycord numeric. UTM West of the point ID
#'
#' @examples
#' retrieve_dist_to_utm(dista = 20, angle = 87, xcord = 432)
#'
#'

retrieve_dist_to_utm <- function(dista, angle, xcord, ycord){

  #calculate coordinates from quadrant coordinates using trigonometry
  if(angle <= 90){
    adj.ang <- (angle*pi)/180
    y.shift <- dista * cos(adj.ang)
    x.shift <- dista * sin(adj.ang)
    point.coords <- c(xcord + x.shift, ycord + y.shift)
  }else{
    if(angle > 90 & angle <= 180){
      adj.ang <-  ((angle - 90)*pi)/180
      x.shift <- dista * cos(adj.ang)
      y.shift <- dista * sin(adj.ang)
      point.coords <- c(xcord + x.shift, ycord - y.shift)
    }else{
      if(angle > 180 & angle <= 270){
        adj.ang <- ((angle - 180)*pi)/180
        x.shift <- dista * sin(adj.ang)
        y.shift <- dista * cos(adj.ang)
        point.coords <- c(xcord - x.shift, ycord - y.shift)
      }else{
        adj.ang <- ((angle -270)*pi)/180
        x.shift <- dista * cos(adj.ang)
        y.shift <- dista * sin(adj.ang)
        point.coords <- c(xcord - x.shift, ycord + y.shift)
      }
    }
  }
  return(point.coords)
}