Hacker News Reader

Comment by throwaway_yy2Di | Hacker News Reader

Offline navigation map for mobile. Small thread here:

https://news.ycombinator.com/item?id=7171919

The entire OpenStreetMap dataset is 23 GiB with moderate compression. With some optimization/truncuation the whole world should fit comfortably on most phones.

This is very useful, for the times you're lost with a slow connection, no connection, in a foreign country, or with roaming charges.

Also it's a fun algorithm-heavy challenge even if you don't finish anything.

View on HN

While offline navigation is increasingly an edge case I do agree that it offers vast utility in the situations where it's still necessary.

Nokia's HERE Drive+ offers this as its headlining feature on Windows Phone, and Windows Phone comes with offline mapping support built in (to be downloaded on a region-by-region basis).

I think the most challenging part of offline mapping is honestly geocoding. Decent vector data for streets is easily available thanks to OSM and learning how to render it and do routing is a fun path down learning well-known algorithms. When you think about it, you're basically reimplementing early 2000s standalone navigation systems like TomTom.

But even once I've implemented rendering and routing (and reached early 2000s TomTom parity), I still can't enter "Pizza Hut" and end up at the nearest Pizza Hut. This is where Google excels over other map providers and especially over the existing mobile-phone offline maps solutions like Nokia's - Google's PoI database and search facility is unmatched in my experience.

Google even solves for fun problems like locating the closest instance of an intersection between common street names like "23rd and Broadway."

Google maps will cache the current map view at the highest detail resolution if you type "ok maps" into the search bar and hit go. You don't even need an active SIM to use gps and zooming. I cached all of central London and used it from my otherwise non-functional Verizon CDMA iphone for months.

Unfortunately, Google maps caching works as view-only. There's no offline navigation at all, I imagine that's all done serverside. Only the tiles (or now vectors) are downloaded.

That's not completely true--if you load your route on wifi and start turn by turn navigation, you can be completely offline.

Do you mean navigation as in "routing" or just as in "viewable map"? If the latter, MapsWithMe does a good job of it already.

Um, never mind then.

http://wiki.openstreetmap.org/wiki/MapsWithMe

12 GB, impressive.

>for the times you're lost with a slow connection, no connection, in a foreign country, or with roaming charges.

I have had exactly this problem this week, so it's been at the top of my mind.

Algorithm-heavy is an understatement. Tasks that are more naturally done by the server (geocoding, routing) have to be shifted onto the client.

Bear in mind that the cases you describe probably are also limited-battery and limited-memory.

There is also some existing competition in this space that you would have to catch up to. Since UI acts as the main differentiator to users in my opinion, that probably ought to be your primary concern at first.

Having said all of that, I would be super-excited to be involved with an Open Source/copyleft project like this.

MapsWithMe[0] lacks routing, but it is an iOS app that provides fast, detailed offline maps with POI's. Data is downloaded by region (for the US, it's by state, for most of the rest of the world, it's by country) and the data is updated pretty frequently. When I was trekking in Nepal, even obscure trails were marked on the maps, which was terrific!

[0] http://mapswith.me/en/home

Reply on news.ycombinator.com