5 Steps to Shade

1) Find an elevation map

The US government has got you (at least on this)

National Map App

Download the elevation as IMG format

img_file <- "~/Downloads/USGS_NED_13_n38w080_IMG/USGS_NED_13_n38w080_IMG.img"

2) Read that map into R

Be careful, they're big fellas

library(rgdal)
GDALinfo(img_file)

## rows        10812 
## columns     10812 
## bands       1 
## lower left origin.x        -80.00056 
## lower left origin.y        36.99944 
## res.x       9.259259e-05 
## res.y       9.259259e-05 
## ysign       -1 
## oblique.x   0 
## oblique.y   0 
## driver      HFA 
## projection  +proj=longlat +ellps=GRS80 +towgs84=0,0,0,-0,-0,-0,0 +no_defs 
## file        ~/Downloads/USGS_NED_13_n38w080_IMG/USGS_NED_13_n38w080_IMG.img 
## apparent band summary:
##    GDType hasNoDataValue   NoDataValue blockSize1 blockSize2
## 1 Float32           TRUE -3.402823e+38         64         64
## apparent band statistics:
##      Bmin    Bmax    Bmean      Bsd
## 1 118.096 1293.38 394.8112 190.6556
## Metadata:
## BandDefinitionKeyword=NONE 
## ConfigKeyword= 
## DataType=Elevation

2b) Read a small chunk of that map into R

Use offset and region.dim to subset

gdal <- readGDAL(img_file,
                 region.dim = c(1000,1000)
                 )

3) Convert to raster

library(raster)
rastr <- raster(gdal)

4) Convert to matrix

dat <- extract(rastr,
               extent(rastr),
               buffer = 1000
               )
mat <- matrix(dat,
              nrow(rastr),
              ncol(rastr)
              )

5) 😎

library(magrittr)
library(rayshader)
mat %>%
  sphere_shade() %>% 
  plot_map()

5b) 😎 🌊 🌓�🌓

mat %>%
  sphere_shade() %>% 
  add_water(detect_water(mat)) %>%
  add_shadow(ray_shade(mat)) %>% 
  plot_map()

5c) 😎 🦄

mat %>%
  sphere_shade(texture = "bw") %>% 
  add_water(detect_water(mat), color = "unicorn") %>% 
  plot_map()

Learn more

Watch the best talk from rstudio::conf 2019

3D mapping, plotting, and printing with rayshader - Tyler Morgan-Wall

Rayshader on GitHub