The CV1 manages user height directly from Oculus Home, and the HTC Vive system detects user height during the room-scale setup procedure. More on this detailed below:
The HTC Vive asks users to locate the floor during the Room Setup procedures. It then calculates user height based on the distance between the floor and the tracked height of the HMD.
During the setup procedures for the Oculus Rift CV1 system, users are asked to input their height, and later during setup the sensor is used to track the HMD and register user eye height.
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