Where is the rotational & positional origin on the physical HTC Vive headset?

[paforbes]

I'm looking to align real world physical objects with the HTC Vives headset transform origin. I need to know where this is on the physical device, so that I can manually measure the distance between it and other physical objects.

Does anyone happen to know?

[HackPerception]

,

It should be on the midline just on the backside of the displays. I'll see if I can find more detailed info. 

 

On the software side, you may need to account for the transforms OpenVR preforms via GetEyeToHeadTransform which controls the scaling of the pose to account for IPD before the data gets converted into whatever coordinate space your engine is using. 

[paforbes]

Hi David,

 

Thanks for the info.   When you say the "backside side of the displays" is that on the inside of the goggles or externally?  

 

Regarding the software statement, we're using Unity, will that effect the transformation?

 

Patrick

[HackPerception]

, towards the outside of the shell; not on the user, side.

 

Yes; so it sounds like you're working with this within Unity's coordinate space and not openVR. The transform happens within SteamVR/OpenVR and that data is then converted into Unity's coordinate system. The entire headtransform scales with the IPD value. How accurate do things need to be? Using the camera rig itself as a frame of reference is probably going to be accurate enough for most use cases.