Override Oculus Orientation 5.3

Question

So with the new VR support the main camera's transform is being overridden with the Oculus transform.

I kinda get this in a general use case but I need to able to override this behaviour.

Specifically I want to override the orientation so that the real world Oculus orientation maps to a greater in-game orientation, particularly on the local y-axis i.e. when I turn my head 90 degrees in the real world, I want to be facing 180 degrees in game.

This is something I have done before in VR on other engines and is a critical part of many locomotion systems you'll see being used.

So how do I go about this, I understand I could always child the camera to a parent and then rotate the parent using the Oculus orientation as a base but this is messy and a bit of a quaternion nightmare.

Answer 1

Answer by zachduer · Oct 24, 2016 at 10:16 PM

Took a few minutes to figure out, but in case anyone in posterity is curious, here's how:

The OVRPlugin class has boolean properties for both position and rotation. Setting these properties in turn calls methods in the oculus plugin itself to enable and disable the position and orientation tracking. Setting rotation in OVRPlugin to false (or, more tediously, getting a reference to the oculus plugin and calling its method: ovrp_SetTrackingOrientationEnabled(false)) will disable rotation transformations from being applied to the camera in Unity.

You can find this at lines 425-435 of the OVRPlugin.cs script that comes in that unitypackage.

The above is true for version 1.8 of Oculus Utilities for Unity 5.

(In retrospect, I realize I'm not 100% answering the question of the OP, as I'm not intercepting the rotation values, but rather disabling them entirely (which is what I needed for my own purpose)).

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roetka · Mar 17, 2017 at 01:33 PM 0

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I know, this thread is a bit older, but I have nearly the same problem right now on my own.

For me, this is not working. I tried it with the Oculus Utilities 1.8 and Unity 5. Can you provide a project with which I can test it out?

Thanks in advance.

zachduer · Mar 17, 2017 at 02:02 PM 0

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Roetka, what exactly are you trying to accomplish?

roetka zachduer · Mar 17, 2017 at 02:17 PM 0

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I need to deactivate the whole tracking of the HMD. In my case I need to deactivate the tracking because I want to use another MoCap System.

zachduer roetka · Mar 17, 2017 at 02:39 PM 0

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Great! I'm doing the exact same thing.

Here is a simplified project that disables both position and rotation from the Oculus. https://drive.google.com/file/d/0B38bbn4KOP60MFliVmhBUkFjbnM/view?usp=sharing

Additionally, though, I will note that I have had best success when using the rotation from the Oculus and the position from the mocap system. The latency from the mocap system is always going to be higher than that of the IMU built into the headset. In this case, you don't need to mess with any scripts at all. In OVRManager, just turn of UsePositionTracking, and then cover the sensor with a piece of tape to double-down and make sure it doesn't send any position data. Then, send your mocap position data to the TrackingSpace transform. The last thing you'll need to do is align the axes of the mocap system with the axes of the IMU rotation. To do that, make a simple script that that calls VR.InputTracking.Recenter(); And maybe have it do that when you press spacebar, or some other hotkey. Then, when you start up, aim the headset toward Z+ in your mocap space and activate that Recenter call, and you'll be set to go. Note that the gyros in the IMU do drift, so you may need to do this every so often during a session.

I've made two scenes in the example project... one to disable all OVR tracking, and one to use rotation from OVR and position from mocap system. It's slightly abstracted because I didn't want to include my own mocap code.

Hope that helps!

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Mastermonk · Mar 17, 2017 at 10:05 PM 0

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@zachduer, thanks for sharing the project. I tried to run it and i would like to do the same as you mentioned. I would like to use the position of the Mocap system (Xsens) and use the orientation of the Oculus. Now I tried the small scene you added "UseOVRRotation". The only thing i'm bumping into is actually attaching it to my Mocap system. Well, attaching works by just draging it onto the neck for example, but i can't get to at that location once booting the game. Could you give a dumbed down explanation on how to get that to work please? Do keep in mind that i'm not much of a programmer, so much of this is pretty new to me.

zachduer Mastermonk · Mar 20, 2017 at 01:21 PM 0

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Hi Mastermonk!

I've never had a chance to use the Xsens suits, so it's possible my reply may not be suitable.

I don't quite understand what you mean that you're not able to "get at that location once booting the game." However, it sounds like what you're trying to do is apply the OVR camera to the head of an avatar that's part of the mocap controlled avatar. This is different than what I'm doing. I'm not using a full avatar; I have a virtual camera being positioned based on the location of a single rigid body. It's unclear to me exactly what you're saying, but I'll take a guess: If you're attaching your camera to the head of your avatar that's part of a skeleton driven by the mocap system, it might be tricky to turn off the mocap rotation of that part of the skeleton and instead use the rotation of the IMU. As a test, I would recommend pulling the camera out of that hierarchy and instead first just try setting its position and rotation to whatever the coordinates are from the mocap, separated from the rest of the skeleton. If that works, go from there, trying to disable the rotation from mocap and use the IMU of the Oculus.

Or, if I'm misunderstanding, please feel free to clarify.

Mastermonk zachduer · Mar 20, 2017 at 03:17 PM 0

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Thanks for the reply. What you are saying is indeed what i'm trying, although i'm not attaching the OVR to the head, but to the neck. I would like to use the orientation of the Oculus instead of the IMU's.

The problem i'm encountering is on how to attach your version to a bone? I'm not a programmer, so most if this is pretty new.

Can I just add a rigid body to the neck and attach the OVR to that?

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Override Oculus Orientation 5.3

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