Libraries

The rayshader package makes it simple to create shaded 2D relief maps.

Since the package is on CRAN, you can install it with install.packages("rayshader").

We also load the raster package to access data to work with.

# install.packages("rayshader")
library(rayshader)
library(raster)

Data format

The rayshader package requires input data in an elevation matrix format. This is a specific matrix where each cell holds the elevation value for the corresponding map point.

Here’s how to obtain the elevation matrix of the Grand Canyon from a raster file using the raster package.

# Define a region for the SRTM data (example: Grand Canyon)
extent_gc <- extent(-113.0, -112.0, 36.0, 37.0)
srtm_gc <- getData("SRTM", lon = -112.5, lat = 36.5)
srtm_gc_cropped <- crop(srtm_gc, extent_gc)

# Convert the raster data to matrix
elevation_matrix <- raster_to_matrix(srtm_gc_cropped)

Basic 2D map

Let’s see how to create a basic 2D map with rayshader.

We use the sphere_shade() function to create the map. It takes the elevation matrix as input and returns a shaded map, and then plot it with the plot_map() function.

elevation_matrix %>%
  sphere_shade(texture="desert", sunangle = 45) %>%
  plot_map()

Change texture

rayshader includes a specialized function to create textures: create_texture(). This function accepts 5 colors as input and generates a texture suitable for use in the sphere_shade() function.

custom_texture <- create_texture("#fff673","#55967a","#8fb28a","#55967a","#cfe0a9")

elevation_matrix %>%
  sphere_shade(texture=custom_texture, sunangle = 45) %>%
  plot_map()

Change shade properties

The add_shadow() function can be used to add a shadow to the map. The ray_shade() function creates a shadow based on the sun angle, while the ambient_shade() function creates a shadow based on the ambient light.

elevation_matrix %>%
  sphere_shade(texture="desert", sunangle = 45, zscale = 50) %>%
  add_shadow(ray_shade(elevation_matrix), 0.5) %>%  # Adds a ray-traced shadow
  add_shadow(ambient_shade(elevation_matrix), 0) %>%  # Adds an ambient shadow
  plot_map()

Going further

You might be interested in

• creating 3d maps with rayshader
• learning more about rayshader