New answers tagged ios
If you use ArcGIS, you could try CarryMap. It is a software tool to export a map from ArcGIS to a mobile device. It supports multiple raster layers. Although you cannot alter the transparency of layers on the mobile device, their transparency is preserved. So if the corresponding ArcGIS raster layers had a transparency setting, the raster is shown with ...
Have you tried GIS 2go (www.gis2go.com). We support offline maps for ArcGIS Desktop (I suppose we are biased, as we developed it, but maybe it fits for your purpose)
The Collector for ArcGIS supports maps with multiple tiled layers. It currently doesn't have offline maps but that will be supported in an update being released this month.
If you are looking to cut down the size of your map data there are in general 3 things you can do: Generalize the geometries (i.e. removed nodes of lines/polygons. The Douglas-Peucker algorithm is a good bet here, used in PostGIS: http://postgis.org/docs/ST_Simplify.html) Remove attributes of your data (I'm not sure how much the attributes on OSM-data ...
You will need to create a data format that is suitable for what you are trying to do. The data format would compress the data, and generally be optimised for what you are trying to do.
You can try to look at the list of OSM apps for iOS. As far as I can see, the only recent open-source application with vector map support for iOS is navit.
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