I’ve been digging into this a bit more. If you create a pawn without a camera, there are a few weird things which happen. But let’s add a camera component. It seems that the Hmd location within the playspace is a CHILD of the camera component. When you click “Lock to Hmd” the camera relative location is set to equal the location of the Hmd within the playspace, giving the impression that the camera and the HMD coordinates are the same, but they are not… If you uncheck “Lock to Hmd”, you can discover that the Hmd relative location within the playspace (that returned by Get Orientation and Position) is actually a child component of the camera. You can get and set the relative position of the camera component, but the Hmd location (and rotation) within the playspace will be ADDED to the cameras relative location. Any Get relative location done on the camera ignores the Hmd offset, and only returns the camera component. Just setting the relative location of the camera moves the camera component but the Hmd continues to move within the child space. Setting the relative location with “Lock to Hmd” enabled doesn’t do anything as I guess the values are overwritten by the Hmd relative location.
I’m now going with “Lock to Hmd” turned off, and offsetting the cameras relative position by the negation of the Hmd position as returned from Get Orientation and Position, and this works:
It’s not perfect however, maybe since the center of rotation is in the middle of the vive helmet but my eyes are on the front of my head… it feels a little off when looking around.