use a grayscale image as a heightmap:

use in-game settings tool (r,g,b color band overlay shown in background)

configure biome interpretation in-game:

results:

perform on-the-fly raster analysis such as slope and aspect:

overlay an image onto the map (here a grayscale version of the same image is used as the heightmap) in 216 colors:

dependencies: requires mod security disabled, for more specific and advanced features an image library will be required, see below...
download latest zip: https://github.com/bobombolo/realterrai ... master.zip
github: https://github.com/bobombolo/realterrain
youtube tutorial: https://www.youtube.com/watch?v=66pehrH6Bh0
license: original content is WTFPL
includes several lua libraries including: magick, imagesize, imlib2, graphicsmagick, lua-socket, lunatic-python (not all are used). ImageMagick is the most tested library for this mod, and until recently was a requirement. GraphicksMagick is recommended for speed and automatic bit-depth detection and handling of strange GIS rasters.
This mod is currently broken
Spoiler
Disabling mod security greatly reduces the security of your system, and should never be done