A cave or other tunnel system (like a mine or a subway or such) may have passages that could twist and turn over and under themselves almost arbitrarily. What best practices do people use to represent this on a 2D flat map?
Color gradient is an excellent way to represent relative changes in elevation. By using a light color for the uppermost level and gradually shifting to a darker color as the elevation descends, it helps make it quickly obvious what is above vs. below.
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