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Can't restart Positional Device Tracker

September 11, 2018 - 7:35am #1

Hi all,

I'm making an iOS app in Unity that uses ARKit. Because I don't have the AR Camera running at all times, I start and stop the PositionalDeviceTracker at certain points in my code. Something like this:

// I do initialize the trackers in code, in case the device doesn't support it (which I check before calling this) 
smartTerrain = TrackerManager.Instance.InitTracker<SmartTerrain>();
positionalDeviceTracker = TrackerManager.Instance.InitTracker<PositionalDeviceTracker>();

//.. User opens AR -> I start the necessary Trackers
// .. User interacts, everything works

// .. Then user quits AR -> I stop the trackers:

The first time everything works fine. However, the second time the user opens AR, I get the beautifully useless error: 'Could not start tracker'. Does anyone have an idea what could be going wrong here? In the Unity Editor this all works (which ofc isn't saying all that much..).

I use practically the same logic for the ObjectTracker (I also use Image Targets), which works like a charm.

Thanks in advance!

Can't restart Positional Device Tracker

September 21, 2018 - 3:38am #3

So I have a toggle that disables and enables the VuforiaBehaviour component on the AR camera, or alternatively I have tried completely disabling and enabling the AR camera GO.

I can then fire off the ResetScene() and ResetTrackers() functions  from PlaneManager, after re-enabling, but this doesn't seem to be enough to get Vuforia back and working correctly.

Applying this logic to your Ground plane core sample scene I can never get the ground plane target to show up again.

I'm permanently stuck with the message "Point device towards ground"

I do seem to be able to place items but the normal functionality of the ground plane never returns.


Also, what are we supposed to do with the TrackableSettings.cs there is no usage information for it?

Is that needed to solve this problem?


Please provide an example in Core samples of how to toggle between a normal camera and an AR camera, without having to leave the AR camera running in the background. Which is not good for performance.


Can't restart Positional Device Tracker

September 11, 2018 - 1:14pm #2

Hello JoeriVDE,

The PlaneManager.cs and TrackableSettings.cs scripts in the Core Samples have example code for starting, stopping, and resetting the PDT. Could you review this and let me know if you are still encountering issues?


Vuforia Engine Support

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