I would like to detect and track simple 2D geometric objects (e.g. red rectangle, blue circle) in an augmented-reality iOS app. Is this something that AR frameworks can do?
E.g. markerless 2D tracking in metaio seems to rely on reference images, which is not quite what I need. I suspect SLAM (as in markerless 3D tracking) may not be appropriate either (2D shapes, user remaining fairly "static" in front of them). Nevertheless, I would prefer to employ such an AR framework instead of a lower-level abstraction such as OpenCV. I would also prefer a framework that includes a free license option (e.g. metaio over Layar).
Specific responses that name an AR framework and appropriate API call (e.g. input: rectangle width/height, video source; output: rectangle x/y/angle in video coordinate system), if applicable, are most welcome. So are first-hand experiences with SLAM in such a scenario.