#' Convert WGS84UTM coordinates TO HK80UTM coordinates
#'
#' Convert WGS84UTM coordinates TO HK80UTM coordinates
#'
#' This functions uses a simplified relationship to convert the coordinates.
#' If zone is 49, res.N = N + 195, res.E = E - 245; if zone is 50, res.N = N +
#' 205, res.E = E - 260
#'
#' @param N Numeric, Northern coordinate in meter
#' @param E Numeric, Eastern coordinate in meter
#' @param zone zone, numeric, either 49 or 50
#' @return \item{N }{Northern coordinates in meters} \item{E }{Eastern
#' coordinates in meters} \item{zone }{either 49 or 50}
#' @note The coordinates should be within the range of Hong Kong. Providing
#' coordinates outside Hong Kong will lead to wrong results.
#' @author Jinlong Zhang
#' @seealso \code{\link{HK80UTM_TO_WGS84UTM}}
#' @references Survey & Mapping Office Lands Department, Hong Kong Government
#' (1995). Explanatory Notes on Geodetic Datums in Hong Kong, available at:
#' \url{http://www.geodetic.gov.hk/smo/gsi/data/pdf/explanatorynotes.pdf}
#' @keywords HK80UTM WGS84UTM
#' @examples
#'
#' #### The similar conversion is not available at
#' #### http://www.geodetic.gov.hk/smo/tform/tform.aspx
#' options(digits = 15)
#' WGS84UTM_TO_HK80UTM(2471279, 205494, zone = 50)
#'
#'
#' @export WGS84UTM_TO_HK80UTM
WGS84UTM_TO_HK80UTM <-
function(N, E, zone = c(49, 50)) {
### The unit for N and E is meter
if (zone == 49) {
res.N <- N + 195
res.E <- E - 245
}
if (zone == 50) {
res.N <- N + 205
res.E <- E - 260
}
return(data.frame(N = res.N, E = res.E, zone = zone))
}
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.