FOSS gamedev and creative worlds

I've seen some servers do it: They have an orthographic map of the generated land of their server's world. How is this done?

Github
This link leads to an python script located in the official minetest repo. If you want a faster version, check the minetest-related projects page of this forum. There is a topic where this script was rewritten in C++

Edit:

https://forum.minetest.net/viewtopic.php?id=2896
^^ ^^
Forum link to the C++ version