13 Rendering 3D
rayshader Stage Route Maps
Having introduced interactive 3d
rayshader models in the previous chapter, let’s now explore how we can generate interactive three dimensional models of our stage maps.
13.1 Load in Base Data
As ever, let’s load in our stage data:
library(tidyr) = 'montecarlo_2021.geojson' geojson_filename = sf::st_read(geojson_filename)geojson_sf
## Reading layer `montecarlo_2021' from data source `/Users/tonyhirst/Documents/GitHub/visualising-rally-stages/montecarlo_2021.geojson' using driver `GeoJSON' ## Simple feature collection with 9 features and 2 fields ## geometry type: LINESTRING ## dimension: XY ## bbox: xmin: 5.243488 ymin: 43.87633 xmax: 6.951953 ymax: 44.81973 ## geographic CRS: WGS 84
We have already seen how we can overlay an elevation model raster on a leaflet map, as well as rendering two dimensional topographic models using the
raytracer package. Generating 3D, rather than 2D, maps follows exactly the same steps as the 2D view apart from the final rendering step.
Recall that the
raytracer package itself works with a matrix of raster values. Having saved the download raster to a tif file, we can load the data back in from and convert it to a matrix using the
library(rayshader) library(raster) # Previously downloaded buffered TIF digital elevation model (DEM) file = "buffered_stage_elevation.tif" stage_tif # Load in the previously saved image raster = raster(stage_tif) elev_img # Get the natural zscale = geoviz::raster_zscale(elev_img) auto_zscale # Note we can pass in a file name or a raster object = raster_to_matrix(stage_tif) elmat
##  "Dimensions of matrix are: 468x626."
Just as a reminder, here’s a quick review of what the 2D maps look like:
# Use the raster extent for the plots = extent(elev_img) stage_extent = generate_line_overlay(geojson_sf[1,], yellow_route extent = stage_extent, heightmap = elmat, linewidth = 5, color="yellow") = elmat %>% mapped_route_yellow sphere_shade(sunangle = -45, texture = "bw") %>% #add_water(watermap, color = "bw") %>% add_overlay(yellow_route) %>% mapped_route_yellow plot_map()
The 2D plots can be quite pretty, but we can also bring them even more alive as 3D rendered plots.
13.2 Setting Up 3D Embedded Plots
Recall that to embed WebGL interactive models using
rgl::rglwidget(), we need to fettle some settings first:
options(rgl.useNULL = TRUE, rgl.printRglwidget = TRUE)
13.3 Rendering a Simple Stage Route Model
We can render our 2D route model simply by passing it to the
rayshader::plot_3d() function, along with the elevation model.
If we set the
zscale parameter to the auto_zscale determined previously as
auto_zscale = geoviz::raster_zscale(elev_img), the relief is rendered using the “real” scaling that keeps the height of elevated areas in equal proportion to the scale used by the x and y scale values:
::clear3d() rgl %>% mapped_route_yellow plot_3d(elmat, zscale=auto_zscale) ::rglwidget()rgl