ENI: Quantifying Environment Compatibility for Natural Walking in Virtual Reality

TL;DR

This paper introduces ENI, a new metric for quantifying how well virtual environments align with physical spaces to enable natural walking in VR, validated through simulations and user studies.

Contribution

ENI is the first general metric capable of automatically identifying compatibility regions between physical and virtual environments for VR navigation.

Findings

Higher ENI scores correlate with longer walking distances before collisions.

ENI effectively highlights incompatible regions in environment pairs.

The metric guides virtual environment design and controller evaluation.

Abstract

We present a novel metric to analyze the similarity between the physical environment and the virtual environment for natural walking in virtual reality. Our approach is general and can be applied to any pair of physical and virtual environments. We use geometric techniques based on conforming constrained Delaunay triangulations and visibility polygons to compute the Environment Navigation Incompatibility (ENI) metric that can be used to measure the complexity of performing simultaneous navigation. We demonstrate applications of ENI for highlighting regions of incompatibility for a pair of environments, guiding the design of the virtual environments to make them more compatible with a fixed physical environment, and evaluating the performance of different redirected walking controllers. We validate the ENI metric using simulations and two user studies. Results of our simulations and user studies show that in the environment pair that our metric identified as more navigable, users were able to walk for longer before colliding with objects in the physical environment. Overall, ENI is the first general metric that can automatically identify regions of high and low compatibility in physical and virtual environments. Our project website is available at https://gamma.umd.edu/eni/.