The increasing availability of displays at lower costs has led to a proliferation of such in our everyday lives. Additionally, mobile devices are ready to hand and have been proposed as interaction devices for external screens. However, only their input mechanism was taken into account without considering three additional factors in environments hosting several displays: first, a connection needs to be established to the desired target display (modality). Second, screens in the environment may be re-arranged (flexibility). And third, displays may be out of the user’s reach (distance). In our research we aim to overcome the problems resulting from these characteristics. The overall goal is a new interaction model that allows for (1) a non-modal connection mechanism for impromptu use on various displays in the environment, (2) interaction on and across displays in highly flexible environments, and (3) interacting at variable distances. In this work we propose a new interaction model called through the display interaction which enables users to interact with remote content on their personal device in an absolute and direct fashion.

To gain a better understanding of the effects of the additional characteristics, we implemented two prototypes each of which investigates a different distance to the target display: LucidDisplay allows users to place their mobile device directly on top of a larger external screen. MobileVue on the other hand enables users to interact with an external screen at a distance. In each of these prototypes we analyzed their effects on the remaining two criteria – namely the modality of the connection mechanism as well as the flexibility of the environment.

With the findings gained in this initial phase we designed Shoot & Copy, a system that allows the detection of screens purely based on their visual content. Users aim their personal device’s camera at the target display which then appears in live video shown in the viewfinder. To select an item, users take a picture which is analyzed to determine the targeted region. We further extended this approach to multiple displays by using a centralized component serving as gateway to the display environment. In Tap & Drop we refined this prototype to support real-time feedback. Instead of taking pictures, users can now aim their mobile device at the display resulting and start interacting immediately. In doing so, we broke the rigid sequential interaction of content selection and content manipulation. Both prototypes allow for (1) connections in a non-modal way (i.e., aim at the display and start interacting with it) from the user’s point of view and (2) fully flexible environments (i.e., the mobile device tracks itself with respect to displays in the environment). However, the wide-angle lenses and thus greater field of views of current mobile devices still do not allow for variable distances. In Touch Projector, we overcome this limitation by introducing zooming in combination with temporarily freezing the video image.

Based on our extensions to taxonomy of mobile device interaction on external displays, we created a refined model of interacting through the display for mobile use. It enables users to interact impromptu without explicitly establishing a connection to the target display (non-modal). As the mobile device tracks itself with respect to displays in the environment, the model further allows for full flexibility of the environment (i.e., displays can be re-arranged without affecting on the interaction). And above all, users can interact with external displays regardless of their actual size at variable distances without any loss of accuracy.