As the use of Head-Mounted Displays in moving vehicles increases, passengers can immerse themselves in visual experiences independent of their physical environment. However, interaction methods are susceptible to physical motion, leading to input errors and reduced task performance. This work investigates the impact of G-forces, vibrations, and unpredictable maneuvers on 3D interaction methods. We conducted a field study with 24 participants in both stationary and moving vehicles to examine the effects of vehicle motion on four interaction methods: (1) Gaze&Pinch, (2) DirectTouch, (3) Handray, and (4) HeadGaze. Participants performed selections in a Fitts' Law task. Our findings reveal a significant effect of vehicle motion on interaction accuracy and duration across the tested combinations of Interaction Method x Road Type x Curve Type. We found a significant impact of movement on throughput, error rate, and perceived workload. Finally, we propose future research considerations and recommendations on interaction methods during vehicle movement.

We present FaceTouch, a novel interaction concept for mobile Virtual Reality (VR) head-mounted displays (HMDs) that leverages the backside as a touch-sensitive surface. With FaceTouch, the user can point at and select virtual content inside their field-of-view by touching the corresponding location at the backside of the HMD utilizing their sense of proprioception. This allows for rich interaction (e.g. gestures) in mobile and nomadic scenarios without having to carry additional accessories (e.g. a gamepad). We built a prototype of FaceTouch and conducted two user studies. In the first study we measured the precision of FaceTouch in a display-fixed target selection task using three different selection techniques showing a low error rate of 2% indicate the viability for everyday usage. To asses the impact of different mounting positions on the user performance we conducted a second study. We compared three mounting positions of the touchpad (face, hand and side) showing that mounting the touchpad at the back of the HMD resulted in a significantly lower error rate, lower selection time and higher usability. Finally, we present interaction techniques and three example applications that explore the FaceTouch design space.

This paper presents Glass Unlock, a novel concept using smart glasses for smartphone unlocking, which is theoretically secure against smudge attacks, shoulder-surfing, and camera attacks. By introducing an additional temporary secret like the layout of digits that is only shown on the private near-eye display, attackers cannot make sense of the observed input on the almost empty phone screen. We report a user study with three alternative input methods and compare them to current state-of-the-art systems. Our findings show that Glass Unlock only moderately increases authentication times and that users favor the input method yielding the slowest input times as it avoids focus switches between displays.

To maintain a mobile form factor, the screen real estate of a mobile device canIn this paper we present SurfacePhone; a novel configuration of a projector phone which aligns the projector to project onto a physical surface to allow tabletop-like interaction in a mobile setup. The projection is created behind the upright standing phone and is touch and gesture-enabled. Multiple projections can be merged to create shared spaces for multi-user collaboration. We investigate this new setup, starting with the concept that we evaluated with a concept prototype. Furthermore we present our technical prototype, a mobile phone case with integrated projector that allows for the aforementioned interaction. We discuss its technical requirements and evaluate the accuracy of interaction in a second user study. We conclude with lessons learned and design guidelines.

The vision of pervasive ambient information displays which show relevant information has not yet come true. One of the main reasons is the limited number of available displays in the environment which is a fundamental requirement of the original vision. We introduce the concept of an Ambient Mobile Pervasive Display AMP-D which is a wearable projector system that constantly projects an ambient information display in front of the user. The floor display provides serendipitous access to public and personal information. The display is combined with a projected display on the user's hand, forming a continuous interaction space that is controlled by hand gestures. The paper introduces this novel device concept, discusses its interaction design, and explores its advantages through various implemented application examples. Furthermore, we present the AMP-D prototype which illustrates the involved challenges concerning hardware, sensing, and visualization.

PriCal is an ambient calendar display that shows a user's schedule similar to a paper wall calendar. PriCal provides context-adaptive privacy to users by detecting present persons and adapting event visibility according to the user's privacy preferences. We present a detailed privacy impact assessment of our system, which provides insights on how to leverage context to enhance privacy without being intrusive. PriCal is based on a decentralized architecture and supports the detection of registered users as well as unknown persons. In a three-week deployment study with seven displays, ten participants used PriCal in their real work environment with their own digital calendars. Our results provide qualitative insights on the implications, acceptance, and utility of context-adaptive privacy in the context of a calendar display system, indicating that it is a viable approach to mitigate privacy implications in ubicomp applications.

Handheld displays enable flexible spatial exploration of information spaces -- users can physically navigate through three-dimensional space to access information at specific locations. Having users constantly hold the display, however, has several limitations: (1) inaccuracies due to natural hand tremors; (2) fatigue over time; and (3) limited exploration within arm's reach. We investigate autonomous, self-actuated displays that can freely move and hold their position and orientation in space without users having to hold them at all times. We illustrate various stages of such a display's autonomy ranging from manual to fully autonomous, which -- depending on the tasks -- facilitate the interaction. Further, we discuss possible motion control mechanisms for these displays and present several interaction techniques enabled by such displays. Our Hover Pad toolkit enables exploring five degrees of freedom of self-actuated and autonomous displays and the developed control and interaction techniques. We illustrate the utility of our toolkit with five prototype applications, such as a volumetric medical data explorer.

We describe the SAWUI architecture by which smartphones can easily show user interfaces for nearby appliances, with no modification or pre-installation of software on the phone, no reliance on cloud services or networking infrastructure, and modest additional hardware in the appliance. In contrast to appliances? physical user interfaces, which are often as simple as buttons, icons and LEDs, SAWUIs leverage smartphones? powerful UI hardware to provide personalized, self-explanatory, adaptive, and localized UIs.

Providing good education is one of the major challenges for humanity. In many developing regions in the world improving educational standards is seen as a central building block for improving socio-economic situation of society. Based on our research in Panama we report on how mobile phones can be used as educational tools. In contrast to personal computers mobile phones are widely available and in Panama over 80% of the children have access to phones. We report on four different studies building on one another. We conducted surveys, focus groups, and group interviews with several hundred teachers and pupils to assess opportunities, needs, and threads for using phones in teaching and learning. Based on the feedback received we created a set of use cases and finally evaluated these in a field study in a rural multigrade school in Panama. Our findings suggest that current phones with multimedia capabilities provide a valuable resource for teaching and learning across many subjects. In particular recording of audio and video, programs for drawing, and taking photos were used in very creative and constructive ways beyond the use cases envisioned by us and initial skepticism of parents turned into support.

In this paper, we introduce Flashlight interaction, a new approach to light-based interaction between mobile phones and large screens by using the phone camera flashlight. Using a mobile phone as an interaction device with large screens has been explored in various projects. Mobile phones are enhanced with different sensors and provide opportunities to be used as an interaction device with other devices such as a large display. Our approach supports to set up a private-public display setting and provide simple means for interaction without a wireless connectivity. Our user study results indicate that the interaction is easy to perform and understand due to the direct mapping between the phone movement and the response on the screen.