This is an old (2017) tutorial I’ve published on my YouTube channel (please suscribe!) in 2017 where I imported points coordinates to obtain quite a good aproximation of the terrain.
The link for downloading the Grasshopper script is right below the video.
You can download the Grasshopper script from the video.

Later in 2018 I’ve created this small script using Elk for Grasshopper.
Here are the links to the script, terrain file and texture:
You can use this website for different areas.