HMD Position Logging

[Annabell]

I want to get the position of the headset in order to decide if someone nodded or shaked his/her head.

Anyone has any idea how I get the position data/values of the headset? Do I need any specific gameObjects?

 

[HackPerception]

@Annabell What's your development environment (Unity/Unreal)?

On the OpenVR SDK side - you can query the pose via the tracking functions within IVRSystem: https://github.com/ValveSoftware/openvr/wiki/IVRSystem_Overview

[Annabell]

I am using Unity

 

@VibrantNebula

[Annabell]

Within Unity I can only download SteamVR Plugin and not OpenVR Plugin. On top of that the IVRSystem seems to be in C++, but within Unity you usually use C#

@Corvus

[Corvus]

@Annabell The HMD position is tracked with the Unity Camera so you can use that to detect head rotation (nodding/shaking).

[Annabell]

Thanks got it

[Asish]

@Annabell Did you get head rotation? If so, how did you detect head rotation? 

[HackPerception]

@Asish Depends on your setup, your engine, etc... Most Unity devs would take their VR camera rig and then script against it to create variables they can then apply conversions on to get an output of an quaternon, a euler angle, or a rotation matrix. It really depends on what your project looks like and how much error is allowable since quaternon or Euler angles will introduce conversion error, especially Euler conversions.

Note that it's particularly a rabbit hole in Unity that can be headache inducing. Here are some posts which may help lead you down a working approaching.

 

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[Asish]

Hello @Corvus @HackPerception

I'm trying to calculate distance between gaze_origin(provided by API) and the target object using following code but the units are not same for these two points. So, how to get same type of coordinate system? 

var d = GameObject.Find("CubeObject").transform.position;

 var combine_gaze = eyeData.verbose_data.combined.eye_data.gaze_origin_mm;

 float dist = Vector3.Distance(d, combine_gaze);

 

Thanks in advance