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#1 2013-10-25 12:33:23

bimmer
Member
Registered: 2013-10-25
Posts: 2

Rendering offline maps on mobile devices

I am considering to build a mobile app that will use the data from openseamap as a foundation for other additional information. The intention is to use the maps in offline mode such that the app will work even without internet connectivity. Therefore I have a couple of questions (newbie in the mapping world).

1. Which of the downloadable map formats would provide the best detail information in the app?
2. Is there any code that may be reused to display the maps in the app?
3. If negative on the above - what would be a suitable way to approach the rendering of maps in a mobile app?

Best

   Brian

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#2 2013-10-26 10:59:17

malcolmh
Member
From: Hull, UK
Registered: 2012-09-05
Posts: 181

Re: Rendering offline maps on mobile devices

There are two basic choices - to cache pre-rendered tiles or to dynamically render from a cached database. Your particular application's requirements will have an impact on your choice, so perhaps you could outline what you have in mind?


Malcolm Herring, Developer

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#3 2013-10-28 10:54:34

bimmer
Member
Registered: 2013-10-25
Posts: 2

Re: Rendering offline maps on mobile devices

My application would place additional layers of live information on top of the map, stuff that would be interesting to people participating at local events etc. I think that for my particular application I would aim at making the rendering at the mobile device as easy and fast as possible, I guess that this points in the direction of have stored pre-rendered tiles on the device. What format is recommendable to use then, given that there seems to be several options there as well??

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#4 2013-10-29 08:18:21

malcolmh
Member
From: Hull, UK
Registered: 2012-09-05
Posts: 181

Re: Rendering offline maps on mobile devices

The tile servers store the rendered map as PNG files, all 256x256 pixels. Details for the OSM tile servers is here: http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

OpenSeaMap tiles are transparent overlays with the same tile addressing scheme, but is stored as a sparse array - where there is no Seamark image there is no tile, so remember to handle 404s as a feature, not a bug!

Our tile URL is: http://t1.openseamap.org/seamark/zoom/x/y.png


Malcolm Herring, Developer

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