Strange values from Get Tracked Device Position And Rotation

Hi everybody,

I might just be slow-witted, but I guess I need your help to understand something and to grasp what I am doing wrong.
With my small setup of two Vive basestations and controllers and UE 4.24.3 I am trying to get my motion controller’s rotation and location without wearing a headset (it is still connected, though. But I don’t want to use it). So I made a simple Actor BP with nothing but a Camera under the DefaultSceneRoot and a static mesh of the controller parented to the camera. I then retrieve the data with Get Tracked Device Position And Rotation and set the relative transform of the camera.

If I play, my tracked location values are pretty far of (about 1180, -324, -248). So as a workaround I take the first measurement and subtract it from all the following measurements and that puts my controller roughly in the world position of the Blueprint in the scene. But this seems unprecise and weird to me.
So my misunderstanding really comes down to what I should expect the controller values to be. Are they relative to some point in my room setup? Or to the headset? How do they get initialized? Or am I messing something up entirely?

If anybody could help me understand my mistake or point me to some reading about what I am missing, I’d be very grateful.
Thanks for your time and help!