
Map Matching in a Programmer's Perspective - hodgesmr
https://github.com/valhalla/valhalla/blob/master/docs/meili/algorithms.md
======
ris
That's fun - when I was working on this problem a few years ago and unable to
find sufficient academic literature on the subject I thought I'd "invented"
what turns out to be known as the Viterbi algorithm (duh) and hadn't thought
too much of it. Turns out what I thought I'd invented is also a HMM, which is
doubly funny because I've never _quite_ managed to wrap my head around HMMs
(though several times I've tried). It's interesting how a lot of algorithms
are a lot more intuitive than most of the rigorous academic notation make them
seem...

Code for anyone interested
[https://bitbucket.org/ris/tsbp/src](https://bitbucket.org/ris/tsbp/src)
[http://wiki.openstreetmap.org/wiki/That_Shouldnt_Be_Possible](http://wiki.openstreetmap.org/wiki/That_Shouldnt_Be_Possible)

Interesting to look back on the code and see that as much effort is spent on
heuristics trying to decide where in the track to spend the calculation effort
than anything else.

~~~
adrianratnapala
Indeed.

The need for rigor often means certain parts of an argument get emphazised
when they distract from the intuitive explanation. Also, when things get
mathematically people have an urge to show how it connects to other
mathematical results. Those connections are interesting in their own right,
but they might not be related to the engineering problem at hand.

The result is that understanding the literature can involve a long hard slog
through other literature, just to discover that most of what you read was
irrelevant.

This is what it is often easier to discover things in the lab than in the
library.

------
drewda
If you'd like to try map matching as a hosted API right away, see screenshots,
demos, and more at [https://mapzen.com/blog/map-
matching/](https://mapzen.com/blog/map-matching/)

Context: This is a link in to Valhalla documentation. Valhalla is an open-
source routing engine led by Mapzen. We also offer it as a hosted SaaS on
mapzen.com

Disclaimer: I work for Mapzen.

