[DavidPeiffer]

My favorite application of dead reckoning is the early 80's Honda system to display the car location on a map. While testing the system, there were times where the car showed itself off of the road. After looking into it further, they learned the map maker had taken some liberties with the exact position of the road, and the vehicle was correct.

Previous discussion: https://news.ycombinator.com/item?id=38135979

[lqet]

Interestingly, if you have good map data, the relative "shape" of you previous trajectory is enough to locate your position globally, without GPS, even without knowing where north is.

https://ad-publications.informatik.uni-freiburg.de/GIS_paths...

[andrewmcwatters]

Thank you for sharing this. I do work in this space and had not come across this before.

[ir77]

that's literally no different than what Google Maps does in my car while in CarPlay mode. It's like Apple neuters it and don't give it full gyro/compass data, because when driving it constantly moves the "car" anywhere from 90 to 270 degress and keeps it there for a few seconds until it figures this out again. I checked all possible permissions and still can't figure it out.

Never happens on the Apple Maps, although I have 0 trust in siri and apple maps, especially when we travel to europe, i feel like i'm an experiment for apple to see how much off straight forward route it can make me take.

[jermaustin1]

I have the same thing happen on Google Maps - on top of my car just spinning in circles, it will also show up 100-300 feet to the right of the road I'm driving on, constantly doing navigation updates to the nearest street. When I unplug from carplay, it's fine, and back on the road, then when I plug it into the car it pops to the right again and starts doing updates.

[pixl97]

Interesting. A number of years ago google maps on apple didn't behave that way. Then one trip I noticed my wife's maps were freaking out in a city with a lot of large curves and clover leaf onramps.

Of course my android with Google maps behaves as expected, though in a few places with stacked interchanges it can get confused if traffic is moving slow.

[chneu]

Not dead reckoning related but for some reason your comment made me think of this.

Map makers make mistakes on purpose. This way they know when someone copies their maps. They look for these little tiny "mistakes".

[Ecgberht]

https://en.wikipedia.org/wiki/Trap_street

[reginald78]

My favorite are the trap towns that didn't exist, but because of the maps with the trap towns on them a form of citogensis occurs and the town is bootstrapped into existence in the real world.

[calvinmorrison]

This seems like it's happening more and more with google maps. I see tons of "Trap Towns" and can't figure out of its realtors making up new neighborhood s to sell houses or them going on google maps, and putting google maps into reality.