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This morning, I was working through the Mixed Reality 250 tutorial. I'm stuck with having one HoloLens join the session that the other HoloLens is currently hosting, because the selectable widget in the UIContainer prefab that should have the information on the hosted session is missing.

I followed all of the necessary steps there. It does deploy successfully through USB.

As someone in a post on the Windows Mixed Reality Developers Forum wrote, it doesn't matter how the software itself is deployed; it's the software itself that determines how two or more HoloLens headsets will share holograms among one another.

They are both connected to the same network on Wi-Fi. On One HoloLens, upon deployment by USB and starting it up [by selecting Start without Debugging in the Debug menu on Visual Studio 2017], I gaze over to the Start button, then I do an air tap gesture on it to start the session. As expected, the demo hologram does show up in front of me, and when I do an air tap with the cursor on it, I am able to move it around with my gaze and see the spatial mapping triangles.

On the other HoloLens, I deploy it by USB and start it up by clicking on [Start without Debugging]. The app does load, except I don't see an option for the hosted session the other HoloLens is running in the Available Sessions list. Even the Join button underneath it has the text completely gray.

I don't understand why I can't join a session on the client HoloLens even if it's on the same network. My two workmates told me that it may have to do with the network itself, but I'm not exactly sure because there may be something that has to do with the HoloLens headsets themselves, or my laptop I'm trying to deploy the solution from. Someone told me further on that I may need a router, but I am not exactly sure on that.

I followed the steps of the setup as is.

Versions of Windows Holographic on both HoloLens headsets are 10.0.14393.2007 and 10.0.14393.448. I don't know if updating the versions would make a difference.

The end goal here is to see if following Mixed Reality 250 can be useful for a project under an NDA where we wanted to deploy it to the HoloLens and enable Spectator View.

I am a university student, and this is my last week of an internship I'm completing.

user9236834
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  • I recall having a similar problem getting the desktop app to connect with the hololens app ([this project](https://github.com/Microsoft/MixedRealityCompanionKit/tree/master/MixedRemoteViewCompositor)). I got it to connect *once* ever and could never figure out why. – Draco18s no longer trusts SE Apr 23 '18 at 22:07
  • Thank goodness I'm not the only one with this problem. – user9236834 Apr 24 '18 at 12:51
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    Try joining an empty router that has no internet and no firewall. Certain firewalls won't allow you to see/join other sessions. It doesn't require you to have internet, only that they are connected to the same network. Or if you don't have that handy, create a hotspot on your phone or something like that. Most likely, your school's network security is to blame. – Dtb49 Apr 24 '18 at 13:58
  • I'll try a hotspot on my phone first. – user9236834 Apr 24 '18 at 14:37
  • What's the minimum bandwidth I need for the router in case I need it, by the way? – user9236834 Apr 24 '18 at 14:40
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    Glad you found an answer! Not something I can try, as I no longer have the device I had access to 9 months ago. :) – Draco18s no longer trusts SE Apr 24 '18 at 20:44
  • There's one thing that bothers me, and we should discuss this in chat rather than comments. For some reason, I can't deploy the solution to both HoloLens headsets by Wi-Fi when both of them, and the laptop I'm deploying the solution from, is connected to the mobile hotspot I have. This is an issue with Microsoft's library for Spectator View, as it has a Unity build window to which you specify the IP addresses of the HoloLens headsets you want to deploy the app to, then buttons to build the solution and deploy it. Not sure why this is the case as a mobile hotspot has no blockers at all. – user9236834 Apr 25 '18 at 13:15

1 Answers1

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I followed Dtb49's comment, where I used my own cell phone with mobile hotspot enabled; I finally see the session I want to join!

Now I can share holograms between the headsets through networking by just air tapping on the option showing the name of the device.

EDIT: I don't know how to do this on iOS, but I do know how to do this on Android phones (specifically, version 7.0).

  1. Tap on the Apps icon on the bottom right.
  2. Swipe to the right once to access the first menu.
  3. Tap on the Settings App.
  4. Tap on the Connections option at the top.
  5. Tap on Mobile hotspot and tethering (You may need to swipe upwards depending on screen resolution)
  6. Tap on the slider for Mobile hotspot to turn it on.
  7. On the computer, connect to the hotspot that holds your mobile phone's model number as the network name. (In the case of Windows 10, click on the radar-like icon in the Toolbar, then select that hotspot and click on "Connect.")
  8. Do the same thing on the Microsoft HoloLens by following the instructions here.
  9. Deploy the built Unity project, holding the code you want to share holograms in between (or the tutorial in this case), to the Microsoft HoloLens using USB.
  10. On one HoloLens, when the app is loaded, gaze down to the "Start" button below the Available Sessions list, then do an air tap. Wait for a moment. (You may want to run the app on Debug mode in case any exceptions are caught for debugging purposes)
  11. On the other HoloLens, once the app is loaded, you should see the session the hosting HoloLens is running. Select it using the gaze and air tap, then gaze on the "Join" button below and do an air tap there.

You should now be able to share the holograms between one another and notice a change in the hologram's position with respect to the real world. Sometimes it helps to use spatial mapping.

user9236834
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