Vuforia 4.0 - Keep Camera Alive disables markers

April 22, 2015 - 7:55am #1

Hi, In my app I have one scene with all the markers and one ARCamera.

The markers uses a custom loadTrackableEventHandler and OnTrackingFound() will load a different scene speficic for each marker.

If I have a camera for each scene all works fine, but on certain devices it loads really slow due to the fact that there is an ARCamera for each scene.

In order to have one camera only I'm trying to use the keepCameraAlive but all the markers are disabled. Its really weird...

If I remove the keepcameraalive all works fine.


Any clue?




Using Vuforia 4.0.105 on unity 4.6.4p3 (but happens on p2 and p1 as well).

Vuforia 4.0 - Keep Camera Alive disables markers

April 26, 2015 - 3:54pm #4

Ok, I finally managed to solve the problem.

Looks like that the keep Alive Behavious is grabbing the markers on Awake() or Start() and disables it (Don't know why but that's exactly whats happening).

I solved by adding the camera to a scene before the scene with markers and it works fine now.


Vuforia 4.0 - Keep Camera Alive disables markers

April 24, 2015 - 12:37am #3

Hi dm3d, yes I did try it but no luck (Also I don't actually need it as I already have markers in each scene).

On my previous project I had this thing working no problem (Vuforia 3, but I found another thread here reporting the same problem on that version as well).


Basically all of my apps are made this way:

- Master Scene (Contains ImageTargets with a custom TrackableEventHandler that will load a scene with the marker's name and one ARCamera with Keep Alive Enabled)

- One scene for each marker with the actual augmentation.

I Do this since Keep Camera Alive was released as it speeds up (A lot) the loading between scene on Android and a bit on iOS.


This is the first time I have this problem, I also tried DontDestroyOnLoad, but I got an exception saying that the camera is accessed by Vuforia and cannot be destroyed.



Vuforia 4.0 - Keep Camera Alive disables markers

April 23, 2015 - 7:10pm #2

Did you also check the box for "Keep Trackable Prefabs Alive"? It is just below the checkbox for "Keep AR Camera Alive".

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