Perhaps I inherited the love of them from my seafaring father. Perhaps my precise, visual, mathematical mind picked up on their usefulness. Perhaps I am OCD. No matter what the reason, I've been fascinated with maps every since I was little. I just finished preparing for my trip to Spain and--in what has become an obligatory part of any preparation--I saved the maps for each of the places I'll be visiting.

I love the fact that reality can be represented in such an intuitive, instantly valuable way. I can look at the map and quickly orient myself, figure out the direction in which I should go. A good map doesn't need a lot of detail to be informative -- all it takes to understand a map is some simple pattern matching, at least one (well, arguably, two) piece of information to match the real life. Maps are, in my view, the original virtual reality.

There is probably also something about how maps easily provide comfort. When I have a map on me, I never feel lost. I feel in control, and in command -- after all, I have the territory charted so it cannot surprise me. This is also why having maps on my mobile phone is one of the most valuable aspects of it.

Did you notice how everyone has their favorite map? Either of a real place, or some treasure map they drew when they were little. In fact, having thought about it, it's not just me: a little bit of map-worship is probably in all of us.

When it comes to electronic maps, I only have one invariant: a map must face north.

I have gotten a lot of weird looks from my friends when I explain to them that I like the Navigation system in my car to have the map facing north (as opposed to facing the direction of travel). Apparently it’s common sense to do the latter.

I disagree. It has everything to do with one’s objectives. If all you care about is optimizing for the user experience understanding directions, then yes, having the map face the direction of travel is better. It’s clear when to turn left and right because the map reflects what ahead of you so you can mimic easily. But for me there is an important objective that I think people undervalue: I value knowing where I am. In other words, I value having a mental model of the area, which allows me to gain intuitive understanding of how far things are and how to get from one place to another without a navigation system (an incredibly useful skill if you don’t have your nav, or if you have the annoying ones that don’t let you the passenger key in directions while you’re driving). There is something really powerful in having a good understanding of your surroundings; it gives you a firm ground.

You simply can’t build that mental model if the map keeps rotating, because there is no invariant that your brain can stick to.

And for anyone who gets confused translating turns on a rotated map into car turns, here is a better paradigm that I use: instead of thinking of turns as “left” and “right”, get used to thinking of them as “clockwise” and “counterclockwise”. Those concepts are invariant under a rotating map so you’ll never get confused.

Admittedly, one difficulty in such an arrangement is turning: it’s not always clear whether to turn left or right if the map is not facing the direction of your travel. Here is a good hack that can help you overcome this difficulty.

Suppose you arrive at a turning point:

Your navigation system (facing north) may show this, for example

It’s not immediately obvious that you’re supposed to turn left, sharply. Here is what you can do: draw an imaginary line that specifies your current direction on the map, and place an imaginary steering wheel at the intersection. Now grab the real steering wheel at the point where the extended line meets an imaginary steering wheel, and turn towards the direction in which you’re heading, like this:

This is how you know which direction to turn in (and how much to turn!)

All you need to do is imagine overlaying the map onto your steering wheel, to know where to grab the steering wheel and how to turn it. The above method has the added benefit of letting you know how much to turn — the sharper the turn, the more you’ll have to rotate the steering wheel!

If you don’t care about the magnitude of the turn, just the direction, a simpler method is simply to turn the wheel in the direction defined by the arc drawn from the final direction to the original one, like this:

A simple way to figure out the direction of turn

In other words, simply imagine placing the map on the steering wheel, grab the wheel at a point where the final direction of travel intersects the steering wheel, and turn it towards the point of intersection of the original direction of travel and the steering wheel.

Try it, it’s really easy, and I know you’ve been antsy to switch the map to be displayed facing north!