I’ve been asked a lot about how to depict different scales recently. The question is – how do you tell the viewer of one map that they’re looking at a zoomed in region of a small area, and on another map convince the viewer that they’re looking at a large area, zoomed out. The easiest cue for the viewer is mountain ranges. These are the feature that’s different enough at different scales that they can act as a defacto scale-bar.
On the left I’ve shown a section of a mountain range pretty zoomed in. Here you can see the individual peaks, and the slopes and crests of the mountains. They take up a large amount of the map and we know we’re looking at a detailed map – similar to the kind of map you might get when exploring hiking trails. This is perfect for a detailed map of the environment around a town, perhaps showing the location of some nearby monster lair or other location of adventure.
On the right I’ve shown a similar map, but the mountains are now just a range. You can’t see the individual peaks, and all you get is the overall sense of a barrier. This is closer to what you might see if you look at the Andes zoomed way out. The lack of distinct detail tells the viewer that you’re looking at a large expanse. You can add a scale of course, but ideally a scale should reinforce the impression the viewer has of the map, rather than being a necessary tool for interpretation.
You can also vary the amount of detail in the coastline. Coasts are fractal, so that’s not strictly going to be a good measure, but it can trick the viewer into thinking that a map is of one scale rather than another.