Registering virtual and real worlds with rt-xr, ARKit and Unity


One of the goals for rt-xr is to allow augmented reality users within a space to collaborate with virtual reality users physically outside of the space, with the VR users getting a telepresent sense of being physically within the same space. To this end, VR users see a complete model of the space (my office in this case) including augmentations while physically present AR users just see the augmentations. Some examples of augmentations are virtual whiteboards and virtual sticky notes. Both AR and VR users see avatars representing the position and pose of other users in the space.

Achieving this for AR users requires that their coordinate system corresponds with that of the virtual models of the room. For iOS, ARKit goes a long way to achieving this so the rt-xr app for iOS has been extended to include ARKit and work in AR mode. The screen capture above shows how coordinate systems are synced. A known location in physical space (in this case, the center of the circular control of the fan controller) is selected by touching the iPad screen on the exact center of the control. This identifies position. To avoid multiple control points, the app is currently started in the correct pose so that the yaw rotation is zero relative to the model origin. It is pretty quick and easy to do. The video below shows the process and the result.

After starting the app in the correct orientation, the user is then free to move to click on the control point. Once that’s done, the rt-xr part of the app starts up and loads the virtual model of the room. For this test, the complete model is being shown (i.e. as for VR users rather than AR users) although in real life only the augmentations would be visible – the idea here was to see how the windows lined up. The results are not too bad all things considered although moving or rotating too fast can cause some drift. However, collaborating using augmentations can tolerate some offset so this should not be a major problem.

There are just a couple of augmentations in this test. One is the menu switch (the glowing M) which is used to instantiate and control augmentations. There is also a video screen showing the snowy scene from the driveway camera, the feed being generated by an rt-ai design.

Next step is to test out VR and AR collaboration properly by displaying the correct AR scene on the iOS app. Since VR collaboration has worked for some time, extending it to AR users should not be too hard.

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