I'm pretty much new to developing AR applications, and I have a task to create a multitarget videos. It should be several image targets presented as a collage and I have android tablets and iPads that should track them from a distance of 2-3m. Is this technically possible ? how good is tracking on this distance and are there any recommendations for which devices should I use and how large my image targets should be? Any other occurrences that I should take care of in this task.