3DoF (three degrees of freedom)
Short definition
3DoF (three degrees of freedom) is the ability of a virtual reality system to track only the rotation of the head, without following the movement of the body through space.
In plain language
With 3DoF, the person can look up, down and to the sides, but if they lean forwards the image does not come closer. It is the natural mode of 360° video, filmed from a fixed point. For seated or lying-down, contemplative sessions it is usually sufficient.
In practice, in an RVer session
The 360° videos in the RVer library work in 3DoF, even on RVer Headsets (which are 6DoF), and are designed for seated or lying-down sessions.