Finding coordinates from heading and distance in R

Question

I want to get the coordinates of new points, preferably using the sf package, when the inital positions and the distance and heading traveled is known. Consider this; we have three points (pts), with a heading and a distance in km attached. How to find the coordinates for the new positions?

library(data.table, dplyr, sf)
dat <- data.table(lon = c(10,10.1,10.4), lat = c(58.4,57.4,57.8), 
                      heading = c(45,10,235), distance_km = c(1,5.3,3))
pts <- dat %>%
      sf::st_as_sf(coords = c("lon","lat")) %>%
      sf::st_set_crs(4326)

Simple feature collection with 3 features and 2 fields
Geometry type: POINT
Dimension:     XY
Bounding box:  xmin: 10 ymin: 57.4 xmax: 10.4 ymax: 58.4
Geodetic CRS:  WGS 84
  heading distance_km          geometry
1      45         1.0   POINT (10 58.4)
2      10         5.3 POINT (10.1 57.4)
3     235         3.0 POINT (10.4 57.8)

Was considering making circles around the points, but dont know how to connect the point to the circle with the correct heading.

buf <- st_buffer(pts, dist = pts$distance_km*1000)
circ <- st_cast(buf, "LINESTRING")

Does this answer your question? [Calculate coordinate from starting point, having distance and an angle for all quadrants](https://stackoverflow.com/questions/33508574/calculate-coordinate-from-starting-point-having-distance-and-an-angle-for-all-q) — TylerH, May 17 '23 at 19:46

score 3 · Answer 1 · answered Nov 03 '21 at 07:56

Found the answer here: Calculate coordinate from starting point, having distance and an angle for all quadrants and here: Convert radians to degree / degree to radians

Will post my R solution for completeness. If anyone has a better or more smooth solution, feel free to post it.

library(data.table, sf, mapview)
dat <- data.table(lon = c(10,10.1,10.4), lat = c(58.4,57.4,57.8), 
                  heading = c(45,10,235), distance_km = c(1,5.3,3))

pts <- dat %>%
  sf::st_as_sf(coords = c("lon","lat")) %>%
  sf::st_set_crs(4326)

pts <- st_transform(pts, 32632)
pts$utm_n <- st_coordinates(pts)[,1]
pts$utm_e <- st_coordinates(pts)[,2]

buf <- st_buffer(pts, dist = pts$distance_km*1000)

circ <- st_cast(buf, "LINESTRING")

rad2deg <- function(rad) {(rad * 180) / (pi)}
deg2rad <- function(deg) {(deg * pi) / (180)}

pts$newp_e <- pts$utm_e + (pts$distance_km*1000* cos(deg2rad(pts$heading)))
pts$newp_n <- pts$utm_n + (pts$distance_km*1000* sin(deg2rad(pts$heading)))

dt <- data.table(pts)

pts2 <- dt %>%
  sf::st_as_sf(coords = c("newp_n", "newp_e")) %>%
  sf::st_set_crs(32632)

mapview(pts2) + mapview(pts, zcol = "heading") + mapview(circ)

Finding coordinates from heading and distance in R

1 Answers1