[chrissnell]

Good, but it's still missing the one key feature that I really need: offline satellite imagery. I guide off-road driving adventures in the western deserts for groups of friends every year. Trip planning is done primary in Google Maps and USGS topos but I occasionally find myself out in the desert and needing to scout a route for a last-minute change but with no way of doing it without Internet and satellite imagery. Yes, it's possible to (legally) cache small amounts of imagery with the stock app but I really want the ability to cache larger areas at high detail. I would pay for this feature, up two a few hundred dollars.

[maxerickson]

There's a whole ecosystem of software for building tile databases and viewing them on phones/tablets:

http://mobac.sourceforge.net/

There's also a bunch of "WMS Viewers" that you can point at National Map endpoints (which shouldn't have any licensing issues):

http://raster.nationalmap.gov/arcgis/rest/services

I've never had a use for them so I don't know if one works well and has nice caching features.

[matt4077]

Mobac works great, although you have to do a bit of editing of configuration files to get it to work with non-free sources like google maps.

I've used it create maps for long bicycle trips in SE Europe. A highest-detail map of the balkans is about 1GB. I used Galileo Offline Maps to render it on an iPhone.

[chrissnell]

Interesting but it looks like the one iOS client for Mobac is geared towards vector maps, not the satellite imagery.

[stevesearer]

I use Gaia GPS for my backcountry hikes which is available for iOS/Android. You can download a variety of topo maps and aerial photos ahead of time in a particular area and load them when out of cell service.

http://blog.gaiagps.com/

https://itunes.apple.com/us/app/gaia-gps-topo-maps-trails/id...

https://play.google.com/store/apps/details?id=com.trailbehin...

The only issue I'm still trying to figure out when using my phone is how to disable the cell antenna with the GPS antenna still activated to conserve battery.

There is also Backcountry Navigator which has similar features but is only available for Android devices: http://backcountrynavigator.com/

[maxerickson]

As far as I know, mobac is only for raster. The app mentioned in a sibling comment supports the tile maps:

https://galileo-app.com/manual.html#offline_maps

I guess it would at least be fine for visualization.

[zytek]

I use MotionX GPS and download data from MotionX Terrain maps (which are OpenCycleMaps), good for getting around where I live. You might check coverage on http://www.opencyclemap.org/

[IvyMike]

> still missing the one key feature that I really need: offline

In general, Google has disdain for the very concept of "offline", so I suspect this feature never happens.