well the way JourneyMap for minecraft works is taht it detects your characters location and ONLY shows the terrain around your character with in a fixed distance from the camera of the character but this only applies to the MINIMAP. the main world map has toggles you can turn on and off for day time, night time, and caves.
in this case the minimap itself would have the toggles for “ground level” and heights. OR you could have it so that the minimap only shows what you can see when in slice view. so depending on the height you have the slice view on it’ll only show what’s visible on that height. tho i’m not sure how much of a resource hog this would become given that the minimap would be constantly changing due to your hearthlings mining, chopping down trees, building structures, etc. Not sure how a minimap could work for this game given the games nature. The minimap would have to be a topdown view of a miniature fully 3d rendered map heights and all.