I am wondering if maybe there is something I am missing in this definition of what is possible: What is the difference between tracking and detecting?
Detection is an object being "found" by Engine SDK in the camera's field of view (FOV), and returning an initial 6DoF pose. Tracking is the continued, real-time return of 6DoF poses from the object that was detected. Note that detection usually takes 1-2 camera frames (very brief), while tracking is continuous while the object is in the camera's FOV.
In the case of Advanced Model Targets, several Model Targets can be bundled into a single device database. When that database is activated, Engine SDK will try to detect all the targets in that database. However, once a target from that set is detected, only one of the targets can be tracked at any given time.
I only need to recognize one model target and perform a full screen action (play a video) and then if another model target appears when back in main screen (after the video), switch to that. I have no need for several at the same time but then how do you switch between them if you cannot track them all at the same time? When I try using more than one model target in my program it will only detect the first one in chronology in Unity, the others are initialized, but never tracked/detected.
My understanding is that you can only activate a single device database containing Model Targets at any given time. Untrained (non-Advanced) Model Targets can only have one object in the device database. Trained (Advanced) Model Targets are recommended for a maximum of 20 objects.
It sounds like a decision on how to create the UX. You could have the user actively select the object and thus you'd activate the corresponding Untrained device database, or you can use a trained device database that contains multiple objects. The SDK will 'detect' the targets in the camera's view, and then it is up to application logic on which one to track.
This use case is covered in the Core Samples (corrected link below), so I suggest your review that Unity Project for more details.
By the way, the second link you sent does not work.
Thanks. Looks like the ending period was included in the URL. Please try this:
Vuforia Engine Support