On Sun, Feb 14, 2016 at 02:47:40PM -0500, Mark Bradley wrote:
The other day I got to thinking-is there no such thing as a GPS/satnav
that can display maps created in an open-source format, such as .pbf?
First of all, navigation requires several features:
* Map display
* Routing graph information
* Address index
The first part is in my experience best done by maintaining a cache of
map tiles in bitmap format on a MicroSD card. If you are moving in a
"new" area for which your device is displaying map tiles for the first
time, then it will take some time to fetch the vector data and render it
into a bitmap. Typically, the device would quickly fetch and display
already rendered tiles from the cache. The Mapsforge library works in
this way.
To my knowledge, Mapsforge supports neither routing nor address search.
For those you would need a different type of index.
I am not aware of any really good open source offline navigation
application for Android. There is OsmAnd, but it consumes a lot of
memory, because it does not maintain a cache of map tiles. It is not
good at calculating routes, especially for bicycling. It can be
interfaced with an external offline router http://brouter.de/ which uses
its own file format.
Brouter can also be interfaced with the closed-source applications Locus
Map and OruxMaps. Both of them are using MapsForge for displaying the
maps. As far as I understand, OruxMaps does not support offline address
search. I have not tried Locus Map, but OruxMaps seems useable on a
low-end device, hardly ever crashing due to running out of memory. It
stores tracks and sensor data in SQLite tables on the MicroSD card.
Perhaps an analogy would be an unlocked cellphone-you pay extra for it
(or hack it), in exchange for additional flexibility. I wonder if
there would be a market for such a thing.
http://linuxg.net/osmscout-is-an-offline-navigation-app-for-ubuntu-touch/
For me, Ubuntu Phone is interesting, but not enough to warrant a
purchase. I hope that there will some day be devices that are based on a
system-on-chip that is supported by the mainline Linux kernel. With both
Android and Ubuntu, my understanding is that upgrading the kernel is
practically impossible, because some drivers are tied to a specific
kernel version.
Marko
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