Comment by Waterluvian | Hacker News Reader

Comment by Waterluvian | Hacker News Reader

Every map lies. Every surficial map especially lies when preserving shape, area, or distance. You can’t get them all.

I especially love the problem space of transit maps. Transit feels like a purely topological endeavour. What nodes connect, how, and what are the edge lengths? But the moment you want to act outside the transit system, you then care about Cartesian accuracy as well. You want to know how far something is from two different transit stops. These kinds of maps can really trick you big time.

When it comes to static maps, you’ve gotta make a compromise. But when it comes to dynamic maps, we could do a ton more. Imagine a map that can trivially toggle and animate between being transit system legible, and surface-level legible. Where in one mode all the lines are nicely laid out to see how they link and their trip times. And another mode every node animates to a new position where they represent the Cartesian coordinates on the surface (another lie of course.)

> Every surficial map especially lies when preserving shape, area, or distance. You can’t get them all.

That's really throwing the baby out with the bathwater. For a map of a city, you can get all three just fine. The curvature of the paper will be within margin of error.

The Cartesian coordinates can also be misleading, since even on foot you can't go in a straight line between any two points. There could be a fence in the middle.

There's also a difference of height. It might take 10 minutes just to get from an underground station to the street level right above it, and you can't go in a straight line there either.

> what are the edge lengths

And what measure do the edge lengths represent: time, distance, map typography?

  When it comes to static maps, you’ve gotta make a compromise

It sounds like the current MTA map is a compromise which enlarges and shrinks parts of the city, but still presented in a way that looks a lot like it's geographically accurate. This could mislead users trying to use the map to estimate real-world distances.

In the article, the MTA talks about displaying the new topological map alongside an accurate geographic map, so that subway users will have both sets of information readily available and clearly distinguished from each other.

When I spent time in Japan, I noticed many that many maps were topological, though perhaps this is because I was looking at tourist maps.

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