1) Don't use terrain component, use a custom mesh for tiles and populate them with the correct textures and combine it with Paged Geometry.
yes, this is what i would do if i did'nt have much Ogre skills and wanted to avoid writing a custom solution...
but now that i think of it, i'm afraid that paged-geometry also does'nt fit your needs...
i did'nt get too deep into paged-geometry code and i don't know how much textures/tiles you have
but i don't think that paged-geometry will load/unload textures from memory for you
you might run into memory/performance issues if you want to load a large amount of textures
http://www.ogre3d.org/forums/viewtopic.php?f=1&t=36346,
in which case you'll need to adapt paged-geometry to your needs...
you can search for info on resource background loading but i think it can be tricker than it sounds( when to load, how to make loading predictable etc... )
i would also suggest that ogre's implementation of back ground-loading is'nt the best fit for this task
but who knows maybe it will work out ok for your needs...
2) Use an external app such as Nasa's World Wind and render it's output to a texture and use that texture as with a mesh(?).
TBH i've never done it but i can think of many ways to present a background texture( it should be easy... )
you can find all of them on the forum-search bar just by typing "background texture" or something like that
you say that having another heavy app running in the background might be an overkill for your needs...
it really depends on how deep you integrate them...its a bit difficult to avoid the overhead of copying a full-screen texture at 60fps but it is possible by hacking into ogre or other engine texture code( make some sort of shared texture )
anyway building an ogre-google-earth sounds like a task i would want to avoid
the pros already did all the hard work and probably optimized it to death( worldWind exist 14 years and OSG is as fast or faster than Ogre1.x )
just consider that they probably generate the tiles on the fly so they don't need to load/unload textures
i'm not sure how time consuming this is, but it still sounds much better than hitting memory barriers created by using/loading texture tiles from disk( texture reading and decoding is a very expensive and memory consuming task )
no, its just a grid-shape for debug purpose, ogitor use it to show the plane+axis of the object you manipulate( rotate, move )
option3: build your own super-optimized custom solution using Ogre and with knowledge from open-source projects...
please consider that i know nothing of your programming back-ground, skills, motivation, available time etc
this can be very tricky...what you want to achieve may be not so simple after all...
http://www.ogre3d.org/forums/viewtopic.php?t=46248
http://www.ogre3d.org/forums/viewtopic.php?f=13&t=56334
edit: check this library:
http://www.gdal.org looks like everybody are using this
someone did ogre-integration but never released the code..
http://www.ogre3d.org/forums/viewtopic. ... highlight=
sorry, their seems to be no easy solution for ogre on this topic so i guess its back to square one...
good-luck...