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I. Podkosova:
"Walkable Multi-User VR: Effects of Physical and Virtual Colocation";
Supervisor, Reviewer: H. Kaufmann, G. Welch, A. Chalmers; 193, 2019; oral examination: 2019-02-08.

The research presented in this dissertation focuses on multi-user VR, where multiple
immersed users navigate the virtual world by physically walking in a large tracking area.
In such a setup, different combinations of user colocation within the physical and the
virtual space are possible. We consider a setup to be multi-user if at least one of these
two spaces is shared. The dissertation starts with the classification of combinations of
physical and virtual colocation. Four such combinations are defined: colocated shared VR,
colocated non-shared VR, distributed shared VR and shared VR with mixed colocation.
The characteristics of each of these four setups are discussed and the resulting problems
and research questions outlined.
The dissertation continues with the description of ImmersiveDeck - a large-scale multi-user
VR platform that enables navigation by walking and natural interaction. Then, four
experiments on multi-user walkable VR developed with the use of ImmersiveDeck are
described.
The first two experiments are set in colocated non-shared VR where walking users share
a tracking space while being immersed into separate virtual worlds. We investigate users´
mutual awareness in this setup and explore methods of preventing mutual collisions
between walking users. The following two experiments study shared VR scenarios in
situations of varied physical colocation. We investigate the effects that different modes
of physical colocation have on locomotion, collision avoidance and proxemics patterns
exhibited by walking users. The sense of copresence and social presence within the virtual
world reported by users is investigated as well.
The experiments in the colocated non-shared VR setup show that HMD-based VR can
produce immersion so strong that users do not notice others being present in their
immediate proximity, thus making collision prevention the task of utmost importance. In
our proposed method of displaying notification avatars to prevent potential imminent
collisions between colocated users, the suitability of a particular type of notification avatar
was found to be dependent on the type of scenario experienced by users. The general
result of the experiments in shared VR is that physical colocation affects locomotor and
proxemics behavior of users as well as their subjective experience in terms of copresence.
In particular, users are more cautious about possible collisions and more careful in their
collision avoidance behavior in the colocated setup compared to the real environment. In
the distributed setup, conventional collision avoidance is often abandoned.
vi

virtual reality, multi-user VR

https://publik.tuwien.ac.at/files/publik_278458.pdf