I have some additional ideas to this!
At first is turn off map for all player. And only player with cartogrpher skill, can draw map, when walk around (something like in Mincecraft) map automaticly draw on paper in hand.
And when draw this map, can give someone else and hi see on minimap only this part of terrain which was drawed for cartographer.
Cartographer skill can be available from Arts skill as map painting on 30 or 60 points
Additional skill to this is a paper craft, which should be available in this same time as FLAX (procuration 90) and this paper should be produced from Pairus Cane, or from Thin leather when had procuration 30 or 60.
And of course to this is necessary Writing Tools from carpenter
on thin leather can only black and white drawings
on papirus player can draw in colours.