Another question for the more technicaly gifted.
I have been using GroundTruth to create countours which works well but the contours are overlayed ontop of the routable map on the GPS. so can make reading mountain roads difficult.
How would I go about generating a background map with all the coastline, poly and filled areas, a middle map with unfilled contours and the top most map with roads and other non filled features?
I don't know about technically gifted ...
What your asking can only be done through creating different transparent imgs and setting different priorities - you either extract the relevant osm with boundaries or rewrite your elements as a .mp file
but even then your gps may decide on its own priorities, particulaly with pois,highways and other lines,ie:
supposing you had a layer for bridges only and create a new img, setting its priority to 30 ; there is no guarrantee that the bridges will always appear on top.
Polygons are better behaved; so you could force your areas to appear at the bottom, using a TYP file to determine their draworders relative to each other.