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SpectatorView with Vuforia

November 30, 2018 - 2:35am #1

Hello,

I am trying to make SpectatorView work with a Vuforia app (Image Target) using a HoloLens and an iPhone.

I delayed the start of Vuforia on both devices so that the HoloLens camera is available to scan the marker on the iPhone and it succeeds to join the session. But once Vuforia starts, two things can happen : either the app on the iPhone crashes but not the one on the HoloLens which is still able to find the target, or the iPhone finds the target and then crashes and the HoloLens app cannot find the image target.

What I would like is just for the HoloLens to find the target and the objects are then displayed on both devices.

Has anybody managed to find a solution and make this work? Is it even possible to make Vuforia work with SpectatorView?

Thank you for your help!

SpectatorView with Vuforia

December 4, 2018 - 3:56pm #2

Hello,

My guess is that this is a similar issue to MRC on HoloLens when using Vuforia.

For HoloLens RS1:

  • You can record videos of Vuforia apps running on HoloLens. Note that for this to work, the app running Vuforia must be started *before* you started to record with HL’s MRC. If you start recording first, the video will abruptly stop once Vuforia gets access to the HL camera.
  • You *cannot* do MRC Live preview while a Vuforia app is running in any case. If you try to start Live preview while a Vuforia-based app is running on HL, you will get an error in MRC. If you try to start a Vuforia-based app while Live preview is running, the app will not start.

For HoloLens RS4:

  • You can record videos of Vuforia apps running on HoloLens. Note that for this to work, the Vuforia performance mode must be set to MODE_OPTIMIZE_SPEED, which sets the camera capture resolution to be 720p, e.g. 1280x720.
  • The app running Vuforia must be started *before* you started to record with HL’s MRC. If you start recording first, the video will abruptly stop once Vuforia gets access to the HL camera.
  • The MRC capture resolution must be set to the same as the Vuforia performance mode (720p)
  • You *cannot* do MRC Live preview while a Vuforia app is running in any case. If you try to start Live preview while a Vuforia-based app is running on HL, you will get an error in MRC. If you try to start a Vuforia-based app while Live preview is running, the app will not start.

We've had mixed success with these steps in RS4, with results in that it works every time to it works once in a while.

The limitations above are related to real-time camera access for apps running on the HoloLens. In order to guarantee optimal detection and tracking performance, Vuforia is granted sole access to the live camera feed. This is similar to other platforms that we support, such as Android and iOS. You can see that it also works the other way around for apps that do not run Vuforia. The Live preview app requires real-time camera access, so while it is running Vuforia is blocked from accessing the camera.

Thanks,

Vuforia Engine Support

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