Maybe you can use something from my examples.
The two coordinate systems are without labeling. Should remain very simple.
Construction of frames with contour/profile
threejsResources/ConstructFrame at master · hofk/threejsResources · GitHub
In the Helper I created numbers from lines.
THREEf.js/THREEh.js at 976360a85a1797f28ef75c8fa29d8744af274a87 · hofk/THREEf.js · GitHub
north and south
It can be combined.