Why does the sunlight come from the north in shaded relief maps? The sunlight in this map comes from the upper left, but in the northern hemisphere the sun mostly occupies the southern half of the sky, so why isn't it coming from below?
Aug 4, 2021 · 1:56 PM UTC
Most folks see the lightest gray side as the top of a cube. Why? Because as humans we tend to assume light comes from above. It is for this reason that cartographers light their maps with the sun positioned above the map, even if it wouldn't be there in reality!
Here's the same area, lit from the north instead of the south. The difference is remarkable isn't it? That same river running along the right now looks like it should: at the bottom of a valley. All we did was change the angle the sunlight was coming from.
As cartographers, we make maps for humans and this means paying attention to how our maps will be perceived. It's true, a map won't always have the sun in a realistic position, but that physical inaccuracy is made up for in a more important dimension: perceptual accuracy.