3D terrain maps

geo_map3d() renders a digital elevation model as a 3D block diagram: the terrain is lit by the sun with cast shadows, seen from any direction and angle, coloured by elevation or by any other raster draped over it (land cover, NDVI, a diversity surface, a model prediction), with sites and routes placed on the surface and hidden where hills are in front of them. The rendering is done in C++ and needs no OpenGL, rgl or rayshader, so it works on servers and in reports; the result is an ordinary ggplot with a title, legend and caption, saved with geo_save().

Usage

geo_map3d(
  dem,
  drape = NULL,
  palette = "auto",
  exaggeration = "auto",
  theta = 200,
  phi = 35,
  sun_azimuth = 315,
  sun_elevation = 35,
  shadow = TRUE,
  ambient = 0.35,
  base = TRUE,
  points = NULL,
  lines = NULL,
  label = NULL,
  point_colour = "#D7301F",
  line_colour = "grey10",
  max_cells = 500,
  width = 1600,
  height = 1100,
  title = NULL,
  subtitle = NULL,
  caption = NULL,
  legend_title = NULL
)

Arguments

dem

A SpatRaster of elevation (metres). Longitude/latitude rasters are projected to UTM first so that heights and distances share units.

drape

What colours the surface: NULL (elevation, hypsometric tints) or a SpatRaster resampled onto the DEM.

palette

Colour ramp for the drape: "auto" (a hypsometric ramp for elevation, a sequential ramp otherwise), a name from grDevices::hcl.pals() or a vector of colours.

exaggeration

Vertical exaggeration. "auto" makes the relief about a fifth of the width of the area, a common choice for block diagrams, between 1 and 8 times.

theta

Direction the viewer looks from, in degrees clockwise from north (180 = from the south, 225 = from the south-west).

phi

Viewing angle above the horizon, in degrees (90 = straight down).

sun_azimuth, sun_elevation

Direction and height of the sun, in degrees. The cartographic default lights from the north-west.

shadow

Cast shadows?

ambient

Share of light in shadow (0 = black shadows).

base

Draw the sides of the block down to a base?

points, lines

Optional sf layers drawn on the surface.

label

Column of points with text labels.

point_colour, line_colour

Colours of the overlays.

max_cells

Largest number of DEM cells along a side; larger DEMs are averaged down to it.

width, height

Image size in pixels.

title, subtitle, caption, legend_title

Text of the figure.

Value

A ggplot. Attribute "render" holds the image and view.

See also

geo_stac_read() to fetch a Copernicus DEM, map_raster() for flat maps.

Examples

elev <- terra::rast(system.file("ex/elev.tif", package = "terra"))
geo_map3d(elev, theta = 200, phi = 35, title = "Luxembourg")