Senses: Sight

Who can read the sign?

A screen only works if people can see it. Two questions every venue asks, answered on the real Mappedin demo maps: where should a mall put its directory, and how many departure boards does an airport need?

Both are about the same thing: from where, and by how many people, a spot can be seen. Every walking point on the floor is a modelled walker, weighted by how many shortest routes pass through it. A walker can read a screen when nothing solid stands between them and it, and it is close enough to read.

Where the mall's directory should go

Malls usually put the directory just inside the main entrance. On Level 1 of the Mappedin demo mall, a screen at the busiest entrance can be read from within 25 m by 10% of walkers. Score every one of the floor's 133 walking points the same way and the best spot reaches 29%, 2.9 times as many. A second screen, placed where it reaches the most walkers the first one misses, takes it to 45%.

Tap anywhere on the map to put a screen there and see its reach. Press Score every spot to colour each walking point by what a screen there would reach, and drag the slider to change how far away a screen can be read.

How many departure boards an airport needs

International Departures in the Mappedin demo airport has 332 walking points, and a board can be read within 20 m. Put up boards one at a time, each where it reaches the most walkers who can't yet read one. The first board reaches 10.6% of walkers. Five boards reach 41.8%. It takes 22 to reach 90%.

The curve flattens fast: every board after the first few covers a corner the others can't see. Step through the boards, or tap the map to add one of your own and see whether it beats the next one on the list.

The same arithmetic places anything that has to be seen: ad screens, wayfinding touch screens, emergency signs. Give it a floor plan and a reading range, and it returns a placement plan and the share of people each screen will reach.

How it's made

Modelled walkers, not footfall. The walkers are the open walking points of the venue's navigation graph, each weighted by betweenness: how many shortest routes, from 200 sampled starting points across the venue, pass through it. That is where people are likely to walk, not a count of where they did.

Sight in 2D. A walker can see a spot when the straight line between them doesn't cross a wall or a room outline from the Mappedin floor plan, and it lies within the reading range. Doors aren't openings, furniture doesn't block, and height, glare and crowds aren't modelled.

Greedy placement. Each next screen goes on the walking point that reaches the most walkers not yet reached. That gives a good plan quickly, but it is not proven to be the best possible one.