Three years ago a similar question was asked, but i think that enough time has passed to make the answers obsolete.
The question is simple, is there a way to do markerless tracking using ARToolKit or other free libraries in the android framework? If there exists a free framework that can do this please, put a reference to the resource.
I have searched a lot, but everything i could find is not given for free, like Vuforia.
What i managed to do until now is to build an opencv app that allows the user to take a pic of the chosen marker, and then OpenGL stuff is rendered on top of the tracked marker. Unfortunately the camera intrinsics is required, and on top of that i have problems related to the tracking, which is quite unstable. For this reasons i am searching some other framework such as ARToolKit, but i couldnt find any reference to markerless tracking.
Thanks in advance
ARToolKit is a marker based AR library (and so is vuforia). I think you're mixing concepts and you want to use an image as marker (which is still a marker)
In that case the answer is yes, you can use ARToolKit. They are called NFT -natural feature trackers-.