Impossible spaces: Maximizing natural walking in virtual environments with self-overlapping architecture

Evan A. Suma, Zachary Lipps, Samantha Finkelstein, David M. Krum, Mark Bolas

Research output: Contribution to journalArticlepeer-review

143 Scopus citations


Walking is only possible within immersive virtual environments that fit inside the boundaries of the users physical workspace. To reduce the severity of the restrictions imposed by limited physical area, we introduce "impossible spaces," a new design mechanic for virtual environments that wish to maximize the size of the virtual environment that can be explored with natural locomotion. Such environments make use of selfoverlapping architectural layouts, effectively compressing comparatively large interior environments into smaller physical areas. We conducted two formal user studies to explore the perception and experience of impossible spaces. In the first experiment, we showed that reasonably small virtual rooms may overlap by as much as 56 before users begin to detect that they are in an impossible space, and that the larger virtual rooms that expanded to maximally fill our available 9.14m x 9.14m workspace may overlap by up to 31. Our results also demonstrate that users perceive distances to objects in adjacent overlapping rooms as if the overall space was uncompressed, even at overlap levels that were overtly noticeable. In our second experiment, we combined several wellknown redirection techniques to string together a chain of impossible spaces in an expansive outdoor scene. We then conducted an exploratory analysis of users verbal feedback during exploration, which indicated that impossible spaces provide an even more powerful illusion when users are naive to the manipulation.

Original languageEnglish (US)
Article number6165136
Pages (from-to)555-564
Number of pages10
JournalIEEE Transactions on Visualization and Computer Graphics
Issue number4
StatePublished - 2012
Externally publishedYes

Bibliographical note

Funding Information:
The projects or efforts depicted were or are sponsored by the U.S. Army. The content or information presented does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred. The authors also wish to thank Gerd Bruder and Frank Steinicke for their assistance with the psychophysical analysis reported in Experiment 1.


  • Virtual environments
  • perception
  • redirection.
  • spatial illusions


Dive into the research topics of 'Impossible spaces: Maximizing natural walking in virtual environments with self-overlapping architecture'. Together they form a unique fingerprint.

Cite this