Calculate coordinates for sampling points along large spatial transects

transect_layout

library(geosphere)

# First, pick a starting point for one of the transects.
start.point.1 <- matrix(data = c(-122.54727, 47.57078), nrow=1)

# Set two other starting points, 1000 meters from the first, in opposite directions
start.point.2 <- destPoint(start.point.1, 30, 1000)
start.point.3 <- destPoint(start.point.1, 210, 1000)

# Pick the distances along each transect you want to sample
transect.pts <- c(4000, 2000, 1000, 500, 250, 125, 75, 50, 0)

# For each start point, give the coordinates for points along a bearing at the distances we set earlier.
transect.1 <- destPoint(start.point.1, 310, transect.pts)
transect.2 <- destPoint(start.point.2, 310, transect.pts)
transect.3 <- destPoint(start.point.3, 310, transect.pts)

# Bind them up into a data frame that you can then print up and drive/walk/boat to!
transect.coords <- rbind(transect.1, transect.2, transect.3)
transect <- c(rep("Transect1", 9), rep("Transect2", 9), rep("Transect3", 9))
point <- rep(transect.pts, 3)
transects <- data.frame(transect, point, transect.coords)
write.csv(transects, "transects.csv")

# here's a simple plot, but you could display these over a map
plot(transects[,3:4])