Generate Compass Overlay
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, 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 )
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. |
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. |
Semi-transparent overlay with a compass.
#Only run these examples if the `magick` package is installed.
if ("magick" %in% rownames(utils::installed.packages())) {
#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()
#Change the position to be over the water
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15)) %>%
plot_map()
#Change the text color for visibility
base_map %>%
add_overlay(generate_compass_overlay(heightmap = montereybay, x = 0.15, text_color="white")) %>%
plot_map()
#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()
#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()
#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()
#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()
#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()
#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()
#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()
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.