hello my name is Julius von Willich and I will
present to you Podoportation foot-based
locomotion in virtual reality. As many
users of VR might know there's a vast
difference between the almost infinite
virtual world virtual reality can present to
the user and the actual physical world
the user resides in this can lead to the
user bumping into their surroundings
which can be circumvented by systems
such as the chaperone system which
displays a grid in front of the user
should they come too close to fit their
physical spaces boundary in applications
this can be prevented by using
artificial locomotion techniques such as
teleportation or button press to move
but those are usually initiated by
pressing a button on a controller in
the users hands although humans use
their hands for much more dexterous tasks
or even for communication in
social interaction furthermore humans
are even capable of using their hands
wild locomoting around the world so
walking and using your smartphone is not
that difficult of a task for
most persons so approaches have been
made to free up the users hands in
virtual reality by approaches such as
head tilting or stepping in place to
elicit locomotion or by redirected
walking which alters the the virtual
world around the user to trick them into
walking circles while believing they are
walking in a straight line which can
also be augmented by using electro
muscle stimulation to force the user to
walk in a tighter circle other
approaches are walk in place such as the
cyberith virtualizer
which holds a user in place and tracks
their feet movement to make them walk in
the virtual world by using minimal space
in the physical world
our approach podoportation uses the
humans feet for teleportation inputs to
allow the user to stay still in the
physical world while still walking
around in the virtual world
and having their hands free for this we
we split up the teleport into its two
main components which is the distance
and the direction of a teleport which
defines a clear target for the user for
distance we defined three input
modalities such as the toe lift which
might remind the user of hand based
teleportation where you can control the
distance of teleport by lifting your
foot to teleport further or putting it
downward to for a shorter teleport the
other input modality we used is foot
distance so we use the distance between
the users feet to control the distance
of the teleport
albeit we exaggerate the teleportation
as to have further teleportation in the
end the third approach for distance we
used is the weight distribution so users
lean forward to teleport further way and
lean backward to teleport a shorter
distance the next component of a
teleport is the direction so for the
direction we also you have three input
modalities one is spanning a vector with
your two feet which we just
stretch out to the final target will
be a distance modifier and the other is
just pointing with your foot towards the
direction that you want to teleport to
and the third is a mixture of the
pointing and from the the input modality
before but you can make smaller
adjustments by leaning left and right so
if you are just slightly to the left or the
right of your target you can make small
adjustments this leaves us with a total
of three input combinations if we
combine all the input modalities with
each other and we wanted to evaluate
them
according to accuracy efficiency and
convenience for the accuracy we used the
error in meters to the desired target of
the user for efficiency we use number of
teleports in task completion time and
for convenience we used a NASA-TLX
and a custom questionnaire the setup was
as follows the user was given a virtual
space which was marked red and green so
the user knew in which direction the
targets they should teleport to would
spawn to reduce search time we had set
distances in which to teleport uh the
targets could spawn and we spawned the
targets at random in this area in front
of the user and only one target at a
time for input we designed this hardware
prototype it had pressure sensors in the
front and in the back and the standard
VIVE Tracker for positional tracking
let's get to the results so concerning
efficiency of the the input modalities
measured in task completion time we
found that the the pressure in distance
the distance pressure modality was
significantly worse than all the other
modalities and no significant
differences between the rest this
compared to the point and teleport which
gives you an indication on how it holds
up to establish teleportation techniques
you can see point and teleport is still
better however we did not introduce an
artificial task which occupies the users
hands which might have increased the
task completion time for point and teleport
but we wanted to have a
baseline that does not include an
artificial task to not skew the results
for the number of teleports we could
find that the toe lift modality is
significantly better so has a
significantly lower number of teleports
compared to the pressure distribution input
modality for distance and no other
significant difference between the input
modalities now for accuracy this is
error in meters to the target we found
that for the distance modality the toe
lift and the foot distance modality was
significantly better than the pressure
modality so less error and for the
direction we also found that the point
with one foot and the point with the
vector of two feet was significantly
better than the pointing with pressure
adjustment so again a smaller error
better result for the NASA task load
index we found that the distance
modality the toe lift and the distance
again were significantly better than the
pressure distribution for the direction
however only pointing with one foot was
significantly better compared to the two
other modalities for the custom
questionnaire we asked for one for the
convenience of the users with the input
modality and the other question was if
they were confident that they arrived
accurately at the target for the
convenience we found that user found the
pointing and toe lift most convenient
for regular use this could be explained
by the user being used to this input
modality from their hand based inputs
from a controller the other question
about the confidences that they arrived
accurately for the foot distance it was
every combination with all the
direction input modalities they were
confident that the distance modality was
that they are arrived accurately at the
target and for the special combination
of toe lift and foot vector so you point
into a direction with both of
your feet that they were confident that
they arrived accurately at the target
furthermore in the questionnaire
we asked the users which input modality
they would like to use in VR in the
future and here we had three input
modalities that users really preferred
the one was pointing with both feet and
lifting your toe pointing
with one foot and distance
of your feet and pointing with both feet
and distance of your feet this could be
due to the fact that engaging your whole
body in the motion made it more engaging
more interesting for the users to teleport
around in the virtual world from this we
could form design guidelines which read as
follows there's no golden bullet for the
teleporting with your feet and you
should only use your feet for
teleportation if the benefit of having
free hands is worth the trade-off or if
you think that tasks done with the
hand will slow down your normal hand-based
teleportation significantly so we
also have two situations to consider one
is do you want convenient locomotion in
this case you should rely on pointing
and foot distance or on pointing and
toe lift however if you want an engaging,
fun, entertaining experience for the
users you should rely on pointing with
both of your feet and distance because
there you modify the whole input
modality at once which the users
really enjoy during the testing
limitations we could see that users
had trouble controlling the center of
pressure of one foot because they are
more used to sensing their whole body
center of pressure which would require
pressure sensors on both feet we saw
that we have no clear indication on how
much improvement the free hands
would actually bring in a real task
since we used a clear baseline with no
secondary tasks in our tests and we also
have no real words tasks at hand so the
users knew exactly whether we're going
they had no obstacles that they had to
work around so it's not comparable to
real-world application at this moment so
in conclusion we have this handy flow
chart so if you really want to use foot
based interaction you have to be sure
that freeing up your hands is really
worth the trade-off if not you should
just rely on standard hand based
teleportation but if you want to trade
off for foot based teleportation the
next question is should it be convenient
or should it be fun for convenience you
should rely on pointing with one foot
and either foot distance or toe lift for
your input modality and if it should be
fun you should rely on pointing with
both feet and relying on foot distance
for the distance input because this
engages the whole users both of the
users feet in the targeting process and
yeah it was generally perceived as more
fun than the other approaches and
finally I would like to invite you to
check out our other tasks at CHI a
virtual CHI that is