Hello, my name is Kevin Pfeil, and I am a student at the University of Central Florida.
Today I will be presenting our work on user perception with a Video See-Through
head-mounted display.
For decades, researchers have studied a phenomenon where people tend to misjudge
distances significantly worse in the presence of virtual stimuli.
Specifically, this misjudgment manifests itself in people underestimating distances. This result
has been observed with Virtual Reality and Optical See-Through Augmented Reality
devices, with researchers pointing to Field of View, Weight, Camera Height,
quality of graphics, and presence of self-avatars as some reasons for this discrepancy.
However, there is a lack of work that uses Video See-Through AR devices to study this effect.
Unlike Optical See-Through devices, which allow the user to see the real world normally,
Video See-Through devices let the user see the real world
through live video displayed on a screen in front of their eyes. Our main research interest for this
work is understanding how users perceive real world distances through this type of device.
Leaders in academia and industry are increasingly using Video See-Through devices for a variety
of applications, including entertainment, remote guidance for manufacturing tasks,
augmentation of daily life experiences, and even eyesight correction. Thus,
it is important to understand if there are perceptual discrepancies with these devices,
especially as applications are trending towards boundless environments.
Therefore, we conducted a user study to help understand differences
in perception of the real world when viewing it through a Video See-Through
device or without one. Our study was 3x4 within-subjects, resulting in 12 conditions.
One independent variable was Device, and the other was Target Distance.
Device had 3 levels – Nothing, where no device was worn;
Video See-Through, where the user wore an HTC Vive with ZED Mini attachment; and Shell,
where a stripped-down Oculus Rift was worn on their head.
We used distances in accordance with previous work
– 3, 4, 5, and 6 meters. We used an indoor lab setting for our environment.
We used a Blind Tossing procedure, where participants closed their eyes and threw a beanbag
to a target on the floor for each of the 12 conditions. Each condition was conducted 3 times,
for a total of 36 trials. The participants had practice throwing beanbags before data collection.
Our participant pool included 24 males and 2 females.
If participants used corrective lenses, they were required to wear them for all trials.
Per condition, we averaged the error of the 3 trials, for a total of 12 datapoints per
participant. We ran a repeated measures ANOVA on our data and found a significant main effect
of each independent variable, but we did not find an interaction effect. Post-hoc t-tests revealed
that Video See-Through and Shell conditions significantly differed
from the Nothing conditions, but they did not differ from each other. Naturally,
participants exhibited more error as the target distance grew.
Although prior work shows how distance underestimation is a non-issue with the HTC Vive,
we found that adding the ZED Mini to the setup resulted in the problem manifesting itself again.
The ZED Mini offers an extremely high resolution, so we don’t anticipate that to be an underlying
cause. It is possible that its extra 63 grams is a contributor, or the fact that the addition of the
camera disrupted the weight distribution of the Vive. However, as the Shell was also significantly
different than normal viewing, we are confident that a reduced Field of View is the main culprit.
Though the Vive has a FOV of 110 by 90 degrees, the ZED Mini reduces this to 90 by 60.
As we look to the exemplars of current Video See-Through HMDs,
we note that the Fields of View for each of them are restricted when compared to the displays,
which boast over 110 degrees. An implication for device manufacturers is to further
development of the imaging devices, so that the field of view is maximized.
But, we also know that field of view reductions help prevent simulator sickness.
Since some of the targeted applications of Video See-Through devices include continuous exposure
in mobile settings, we want to emphasize that we must now work to balance physical
user safety and risk of simulator sickness. Future work will help tackle these issues,
so that we can successfully deploy these powerful applications beyond the laboratory.
Thank you for tuning into my presentation.