nether maps don't work

would like to see maps in the nether be able to be opened and work. my idea for it is the following:

if you open a map below y=128, it shows the highest terrain, for example, if you open it in a crimson forest, it shows the nether wart and thecrimson netherrack stuff.

above y=128 it shows everything you've built from a bird's eye view of y=256, so you can see roof nether portals and gold farms etc.

nether caves do not show.

you could also just do it so that the map has the nether biomes on it. (blue:warped forest, red:crimson forest, black:nether wastes, brown:soul dand valley)