This adds the compass
Based on code from "Auxiliary Cartographic Functions in R: North Arrow, Scale Bar, and Label with a Leader Arrow"
generate_compass_overlay(
x = 0.85,
y = 0.15,
size = 0.075,
text_size = 1,
bearing = 0,
heightmap = NULL,
width = NA,
height = NA,
resolution_multiply = 1,
color1 = "white",
color2 = "black",
text_color = "black",
border_color = "black",
border_width = 1,
halo_color = NA,
halo_expand = 1,
halo_alpha = 1,
halo_offset = c(0, 0),
halo_blur = 1
)Arguments
- x
Default `NULL`. The horizontal percentage across the map (measured from the bottom-left corner) where the compass is located.
- y
Default `NULL`. The vertical percentage across the map (measured from the bottom-left corner) where the compass is located.
- size
Default `0.05`. Size of the compass, in percentage of the map size..
- text_size
Default `1`. Text size.
- bearing
Default `0`. Angle (in degrees) of north.
- heightmap
Default `NULL`. The original height map. Pass this in to extract the dimensions of the resulting RGB image array automatically.
- width
Default `NA`. Width of the resulting image array. Default the same dimensions as height map.
- height
Default `NA`. Width of the resulting image array. Default the same dimensions as height map.
- resolution_multiply
Default `1`. If passing in `heightmap` instead of width/height, amount to increase the resolution of the overlay, which should make lines/polygons finer. Should be combined with `add_overlay(rescale_original = TRUE)` to ensure those added details are captured in the final map.
- color1
Default `white`. Primary color of the compass.
- color2
Default `black`. Secondary color of the symcompass.
- text_color
Default `black`. Text color.
- border_color
Default `black`. Border color of the scale bar.
- border_width
Default `1`. Width of the scale bar border.
- halo_color
Default `NA`, no halo. If a color is specified, the compass will be surrounded by a halo of this color.
- halo_expand
Default `1`. Number of pixels to expand the halo.
- halo_alpha
Default `1`. Transparency of the halo.
- halo_offset
Default `c(0,0)`. Horizontal and vertical offset to apply to the halo, in percentage of the image.
- halo_blur
Default `1`. Amount of blur to apply to the halo. Values greater than `30` won't result in further blurring.
Value
Semi-transparent overlay with a compass.
Examples
if(run_documentation()) {
#Create the water palette
water_palette = colorRampPalette(c("darkblue", "dodgerblue", "lightblue"))(200)
bathy_hs = height_shade(montereybay, texture = water_palette)
#Generate flat water heightmap
mbay = montereybay
mbay[mbay < 0] = 0
base_map = mbay %>%
height_shade() %>%
add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>%
add_shadow(lamb_shade(montereybay,zscale=50),0.3)
#Plot a compass
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay)) %>%
plot_map()
}
if(run_documentation()) {
#Change the position to be over the water
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15)) %>%
plot_map()
}
if(run_documentation()) {
#Change the text color for visibility
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, text_color="white")) %>%
plot_map()
}
if(run_documentation()) {
#Alternatively, add a halo color to improve contrast
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
halo_color="white", halo_expand = 1)) %>%
plot_map()
}
if(run_documentation()) {
#Alternatively, add a halo color to improve contrast
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
halo_color="white", halo_expand = 1)) %>%
plot_map()
}
if(run_documentation()) {
#Change the color scheme
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
halo_color="white", halo_expand = 1, color1 = "purple", color2 = "red")) %>%
plot_map()
}
if(run_documentation()) {
#Remove the inner border
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
border_color=NA,
halo_color="white", halo_expand = 1,
color1 = "darkolivegreen4", color2 = "burlywood3")) %>%
plot_map()
}
if(run_documentation()) {
#Change the size of the compass and text
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.75, y=0.75,
halo_color="white", halo_expand = 1,
size=0.075*2, text_size = 1.25)) %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.45, y=0.45,
halo_color="white", halo_expand = 1,
size=0.075)) %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
halo_color="white", halo_expand = 1,
size=0.075/2, text_size = 0.75)) %>%
plot_map()
}
if(run_documentation()) {
#Change the bearing of the compass
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.85, y=0.85,
halo_color="white", halo_expand = 1, bearing=30,
size=0.075)) %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.5, y=0.5,
halo_color="white", halo_expand = 1, bearing=15,
size=0.075)) %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
halo_color="white", halo_expand = 1, bearing=-45,
size=0.075)) %>%
plot_map()
}
if(run_documentation()) {
#Create a drop shadow effect
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, y=0.15,
text_color="white", halo_alpha=0.5, halo_blur=2,
halo_color="black", halo_expand = 1, halo_offset = c(0.003,-0.003))) %>%
plot_map()
}
