I realise there are a fair few threads asking for this type of stuff, but most are rather old and I thought I'd start one to talk about some implementation specifics.

I also realise that we lack a digital compass, but there's always the option to swipe to move the view and I'm ever hopeful someone will find/make a Bluetooth compass, and also that any future devices will actually come with this important bit of hardware. Hint, hint, Nokia!

There are already some apps for Android and the iPhone (mostly closed source it seems, e.g. laylar, Wikitude), and it seems a shame that there's no framework for us to hack on.

My interest is mainly in augmenting what you can see through the camera (rather than generating renderings that you can manipulate by moving the N900 as I think arapp does). A random selection of interesting things one could try to do:

- overlay local wikipedia entries on camera view
- overlay stars data on camera view (not sure the camera can see stars mind you)
- overlay marker and distance to things like local shops, pubs, restaurants, bus stops, etc., etc.
- overlay route data on camera view...

So, the question is, does anyone know of any existing frameworks that might be suitable to develop some proof of concept code on the N900?

There's certainly ARToolKit, but this seems to me to be mainly aimed at realtime camera tracking/orientation using markers in the FOV. This is something that wouldn't be available when looking at the real world (and assuming we'd trust the GPS & compass) would also not be needed.

There are others such as Mixare that are targeted at Android, so not much use there. I note that OpenMAR is targeted at Symbian (and therefore will be written in something approaching C++, but again the differences between the platforms are quite significant).

So anyone have any thoughts, or is it worth just writing something from scratch (and polishing up my OpenGLES knowledge!)?