Augmented Reality (AR) interfaces have been studied extensively over the last few decades, with a growing number of user-based experiments. In this paper, we systematically review 10 years of the most influential AR user studies, from 2005 to 2014. A total of 291 papers with 369 individual user studies have been reviewed and classified based on their application areas. The primary contribution of the review is to present the broad landscape of user-based AR research, and to provide a high-level view of how that landscape has changed. We summarize the high-level contributions from each category of papers, and present examples of the most influential user studies. We also identify areas where there have been few user studies, and opportunities for future research. Among other things, we find that there is a growing trend toward handheld AR user studies, and that most studies are conducted in laboratory settings and do not involve pilot testing. This research will be useful for AR researchers who want to follow best practices in designing their own AR user studies.

Interfaces for collaborative tasks, such as multiplayer games can enable more effective and enjoyable collaboration. However, in these systems, the emotional states of the users are often not communicated properly due to their remoteness from one another. In this paper, we investigate the effects of showing emotional states of one collaborator to the other during an immersive Virtual Reality (VR) gameplay experience. We created two collaborative immersive VR games that display the real-time heart-rate of one player to the other. The two different games elicited different emotions, one joyous and the other scary. We tested the effects of visualizing heart-rate feedback in comparison with conditions where such a feedback was absent. The games had significant main effects on the overall emotional experience.

In the past, several systems have been presented that enable users to view occluded points of interest using Augmented Reality X-ray visualizations. It is challenging to design a visualization that provides correct occlusions between occluder and occluded objects while maximizing legibility. We have previously published an Augmented Reality X-ray visualization that renders edges of the occluder region over the occluded region to facilitate correct occlusions while providing foreground context. While this approach is simple and works in a wide range of situations, it provides only minimal context of the occluder object. In this paper, we present the background, design, and implementation of our novel visualization technique that aims at providing users with richer context of the occluder object. While our previous visualization only employed one salient feature (edges) to determine which parts of the occluder to display, our novel visualization technique is an initial attempt to explore the design space of employing multiple salient features for this task. The prototype presented in this paper employs three additional salient features: hue, luminosity, and motion. We have conducted two evaluations with human participants to investigate the benefits and limitations of our prototype compared to our previous system. The first evaluation showed that although our novel visualization provides a richer context of the occluder object, it does not impede users to select objects in the occluded area; but, it also indicated problems in our prototype. In the second evaluation, we have investigated these problems through an online survey with systematically varied occluder and occluded scenes, focussing on the qualitative aspects of our visualizations. The results were encouraging, but pointed out that our novel visualization needs a higher level of adaptiveness.

Handheld Augmented Reality (HAR) has the potential to introduce Augmented Reality (AR) to large audiences due to the widespread use of suitable handheld devices. However, many of the current HAR systems are not considered very practical and they do not fully answer to the needs of the users. One of the challenging areas in HAR is the in-situ AR content creation where the correct and accurate positioning of virtual objects to the real world is fundamental. Due to the hardware limitations of handheld devices and possible restrictions in the environment, the correct 3D positioning of objects can be difficult to achieve we are unable to use AR markers or correctly map the 3D structure of the environment.We present SlidAR, a 3D positioning for Simultaneous Localization And Mapping (SLAM) based HAR systems. SlidAR utilizes 3D ray-casting and epipolar geometry for virtual object positioning. It does not require a perfect 3D reconstruction of the environment nor any virtual depth cues. We have conducted a user experiment to evaluate the efficiency of SlidAR method against an existing device-centric positioning method that we call HoldAR. Results showed that SlidAR was significantly faster, required significantly less device movement, and also got significantly better subjective evaluation from the test participants. SlidAR also had higher positioning accuracy, although not significantly

Empathic Computing is a research field that aims to use technology to create deeper shared understanding or empathy between people. At the same time, Mixed Reality (MR) technology provides an immersive experience that can make an ideal interface for collaboration. In this paper, we present some of our research into how MR technology can be applied to creating Empathic Computing experiences. This includes exploring how to share gaze in a remote collaboration between Augmented Reality (AR) and Virtual Reality (VR) environments, using physiological signals to enhance collaborative VR, and supporting interaction through eye-gaze in VR. Early outcomes indicate that as we design collaborative interfaces to enhance empathy between people, this could also benefit the personal experience of the individual interacting with the interface.

Augmented Reality (AR) applications on mobile devices like smartphones and tablet computers have become increasingly popular. In this paper, for the first time in the AR domain, we present: (1) the influence of different handheld displays and (2) the exocentric depth perception. Unlike egocentric depth perception, exocentric depth perception has not been investigated in AR. We have selected a suitable vision-based tracking method for our user studies based on a set of evaluations. Then we have investigated the effect of display size and resolution through two user studies. One study investigated the effect of different displays on egocentric depth perception. The other study investigated the effect of displays on exocentric and ordinal depth perception. Interestingly, we noticed depth compression is less when using a mobile phone, while participants subjectively preferred a tablet. A similar effect was also noticed in exocentric depth perception. The tablet provided significantly better ordinal depth perception and faster response time than the mobile phone. In both of the studies, we found no effect of the AR X-ray visualization on depth perception. Both egocentric and exocentric distances were underestimated.