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Comment by danpat | Hacker News Reader

It's mostly a question of storage.

Here's a great tool for getting a feel:

http://tools.geofabrik.de/calc/#type=geofabrik_standard&bbox...

Z=18 is rarely used, so for Z<=17 you're looking at roughly 300MB for raster tiles a city the size of Calgary. You also don't get routing information with purely raster data.

You could try vector data which would be smaller, but then you have to display it, which can be computationally expensive if you want it to look pretty, and you'd lose the snappiness you're seeking.

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You've just told us a good-sized city fits in about 1/200th of my phone's storage. I'll take a dozen.

Actually, you could fit the entirety of the state of Washington in <50% of my phone's storage.

I'm not seeing a problem.

>Actually, you could fit the entirety of the state of Washington in <50% of my phone's storage. I'm not seeing a problem.

Well, most people don't want to lose even 20% of their phone's storage in a single app, much less 50%.

And that's just for those satisfied to only have info for one state. What about people regularly travelling between 1-2 states?

That said, I question the OP storage math. At least with vector information, I know that something like Navigon's GPS/map app, can store the whole of US (including the smallest of towns and cities) in around 1GB.

The OpenStreetMap vector data for Calgary is about 6.2MB-20MB, depending on the format.

Vector data has a much smaller footprint in most cases, but takes lots of processing to render, and even more if you need to be able to zoom around the map. Rendering the US down to z17 as raster tiles allows for efficient processing, but could easily get into 10s of GB (which makes sense, since it is creating thousands and thousands of png images). The size grows exponentially with each zoom level though, so if you only need something like z12, you might be able get it into the 10s of MB range.

I wasn't saying I would want the entirety of Washington on my phone. Quite the contrary. I was pointing out the sheer area that fits in that amount of storage. It's 71,362 square miles.

If you're traveling regularly between two states, you'd want your origin city, destination city, and your route with maybe a couple miles on either side. Say a 250-mile route, and 200 square miles at either end. I bet it fits in <2GB.

You demonstrated quite eloquently that in this case, offline is superior.

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