Camera phones, of course, were
a key driver for the content sharing—locally and remotely—that
became the social-networking ecosystem. For those of us involved
in pico-projection research, the
question is, what sort of changes
might be in store 10 years from
now if high-performance projectors become mainstream?
Here we take a closer look at the
challenges and design questions
that need addressing, touching on
technical, interaction, application,
and social issues. We look at the
commercial state of the art and
look forward to the possible future
envisioned in research labs.
March + April 2012
interactions
Technical Issues
Let’s turn first to the most obvious apparent limitation: output
brightness. Current personal
projectors can display between
20 and 50 lumens, which might
increase up to 100 lumens in
the next few years. They are
therefore not nearly as bright as
some low-cost fixed projectors,
which can have more than 2,500
lumens. This implies that personal
projectors can only effectively
be used indoors without direct
sunlight and outdoors at night.
However, a key element is energy consumption. The brightness
output of projectors seems to have
been driven by the movie-watch-ing scenarios mentioned here. The
projectors must be able to provide
90 minutes to two hours of projection time on a single charge. If
manufacturers allowed applications or users to trade brightness
for energy consumption, then it
would be quite possible to enable a
brighter projection for shorter and
more frequent usages of a projector phone in truly mobile settings.
The physical size of pico projec-
tors is constrained by the projec-
tor hardware and the battery,
which together is in the region of
20 cm3. This is small enough for
devices like mobile phones but
too large to include them, in the
medium term, in small, wearable
devices like earphones, watches,
or clip-on music players. So for
the time being, these are going to
be handheld interaction devices.
Novel Interactions and
Applications
While the technical platform is
already at a stage to afford interesting interactions and applications,
the commercial reality at present is
somewhat pedestrian. In fact, the
level of interactivity is similar to
that of a laptop being connected to
an ordinary projector. The image to
be projected is typically the same
as what’s on the mobile display,
and interaction is limited to the
device itself. The interaction and
display space remain separate; the
user does not directly interact with
the projection itself. Interaction on
the device (e.g., via multi-touch) or
with the device (e.g., using tilt gestures) has influence on one single
display. If the image is projected,
the main benefit is that it can easily be shared among a small group
of users. Interaction with the projection itself is limited to changing
the position and scale, as the usage
situation requires.
There is so much more that can
be done [ 1]. A simple step, of course,
is to decouple the device’s display—
the phone’s or tablet’s touchscreen,
for instance—from the projection
(see NTT DoCoMo [ 2]). This would
allow interaction with different
views of the same data at once.
However, there are more exciting ways of using mobile projections. Imagine a space in front of
you right now—perhaps the wall
of the cafe where you are sipping
cappuccino while reading this
article—as draped in an invisible
canvas. While pointing on this
surface with your tiny handheld
projection device, you can reveal
parts of the information space
as if they were located under a
spotlight. Tracking the device’s
absolute position with regard to
the wall allows the appropriate
parts of the overall information