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