I know that Rob (Rubke) wrote a tool that is called OSMtiledownloader.
http://wiki.openstreetmap.org/index.php/OSMtiledownloader
It allows you to download tiles to the desktop given a certain directory
structure. This directory can then be copied to a mobile device and used
in conjunction with OSMTracker
http://wiki.openstreetmap.org/index.php/Osmtracker
This solves the issue of complex rendering, and give you a base set of
tiles. OSMtracker also has a live tile download function, but it is not
the fastest around yet.
So I disagree that you would need a mini mapnik on your mobile. I think
it might be good to build a standard API to handle rendering tiles based
upon a certain directory structure and a download API for getting tiles
into your phone via GPRS. The both combined will probably require less
processing power then setting up a mapnik server on the phone.
Martijn Pannevis schreef:
Robert (Jamie) Munro wrote:
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Jason Dent wrote:
| I have a mobile map application. I have found that directly accessing the
| tile server works the best.
The downloads are HUGE! Some people have to pay per kB for mobile
downloads. Also, you can't rotate and reproject the tiles, or give a
sat-nav type 3d view, without horribly distorting the text. If you want
to highlight a road or a point, you have to download the map details anyway.
| Trying to draw all the map details at runtime
| on a PDA is a bit much. It can be done, but pre-cooked tile are much
| better.
It's not "a bit much". *All* commercial sat-navs do it. When you
consider how much more CPU power a modern PDA has than a PC of 15 years
ago, and think about the kind of thing those PCs did (Doom, for example)
drawing a map is easy.
I agree that technically redering tiles on the mobile probably would be
the best solution, certainly in terms of data traffic.
However, to get nice looking tiles, you'd have to implement something
like mapnik, on your device. I know it already took us quite some work
to implement a nice map with scrolling tiles in J2ME. I'm sure building
that with vectors, which scale with zoomlevels, and look nice, would
take months, if not years, of development time. Thats why we choose to
use tiles.
I do want to look into more efficient ways of getting tiles, or parts of
them, to the mobile.
Kind Regards,
Martijn Pannevis.
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