This letter presents an alternative, more consistent, construction for bridging distributions, which enables inferring the destination of a tracked object from the available partial sensory observations. Two algorithms are then introduced to sequentially estimate the probability of all possible endpoints within a generic Bayesian framework. They capture the influence of intended destination on the object's motion via suitably adapted stochastic models. Whilst the bridging approach has low training requirements, the proposed formulation can lead to more efficient predictors, e.g. around 65% less computations for certain models. Synthetic and real data is used to illustrate the effectiveness of the introduced algorithms.

Using interactive displays, such as a touchscreen, in vehicles typically requires dedicating a considerable amount of visual as well as cognitive capacity and undertaking a hand pointing gesture to select the intended item on the interface. This can act as a distractor from the primary task of driving and consequently can have serious safety implications. Due to road and driving conditions, the user input can also be highly perturbed resulting in erroneous selections compromising the system usability. In this paper, we propose intent-aware displays that utilize a pointing gesture tracker in conjunction with suitable Bayesian destination inference algorithms to determine the item the user intends to select, which can be achieved with high confidence remarkably early in the pointing gesture. This can drastically reduce the time and effort required to successfully complete an in-vehicle selection task. In the proposed probabilistic inference framework, the likelihood of all the nominal destinations is sequentially calculated by modeling the hand pointing gesture movements as a destination-reverting process. This leads to a Kalman filter-type implementation of the prediction routine that requires minimal parameter training and has low computational burden; it is also amenable to parallelization. The substantial gains obtained using an intent-aware display are demonstrated using data collected in an instrumented vehicle driven under various road conditions.

With the proliferation of the touchscreen technology, interactive displays are becoming an integrated part of the modern vehicle environment. However, due to road and driving conditions, the user input on such displays can be perturbed resulting in erroneous selections. This paper describes an evaluative study of the usability and input performance of in-vehicle touchscreens. The analysis is based on data collected in instrumented cars driven under various road/driving conditions. We assess the frequency of failed selection attempts, distances by which users miss the intended on-screen target and the durations of undertaken free hand pointing gestures to accomplish the selection tasks. It is shown that the road/driving conditions can notably undermine the usability of an interactive display when the user input is perturbed, e.g. due to the experienced vibrations and lateral accelerations in the vehicle. The distance between the location of an erroneous on-screen selection and the intended endpoint on the display, is closely related to the level of present in-vehicle noise. The conducted study can advise graphical user interfaces design for the vehicle environment where the user free hand pointing gestures can be subject to varying levels of perturbations.

Augmented reality (AR) adds virtual graphics, sounds or data to a real-world environment. Future Head-Up Displays in vehicles will enable AR images to be presented at varying depths, potentially enabling additional cues to be provided to drivers to facilitate task performance. In order to correctly position such AR imagery, it is necessary to know at what point the virtual image is discriminable in depth from a real-world object. In a two-alternative forced-choice psychophysical depth judgment task, 40 observers judged if an AR image (a green diamond) appeared in front or behind a static 'pedestrian' target. Depth thresholds for the AR image were tested with the pedestrian target at 5m, 10m, 20m and 25m and at six locations relative to the pedestrian. The AR image was presented at different heights in the visual field, (above, middle and below the real-world target) and across the horizontal plane (left, middle, right of the real-world target). Participants were more likely to report that the AR image was presented in front of the target rather than behind. Inconsistent with previous findings, no overall effects of height or horizontal position were found. Depth thresholds scaled with distance, with larger thresholds at further distances. Findings also showed large individual differences and slow response times (above 2.5s average), suggesting of difficulties judging AR in depth. Recommendations are made regarding where a HUD image should be located in depth if a designer wishes users to reliably perceive the image to be in front/alongside or behind a real-world object.

We propose a novel probabilistic inference approach that permits predicting, well in advance, the intended destination of a pointing gesture aimed at selecting an icon on an in-vehicle interactive display. It models the partial 3D pointing track as a Markov bridge terminating at a nominal destination. The solution introduced leads to a low-complexity Kalman-filter-type implementation and is applicable in other areas in which early detection of the destination of a tracked object is beneficial. Data collected in an instrumented vehicle illustrate that the proposed technique can infer the intent notably early in the pointing gesture. This can drastically reduce the pointing task time and visual-cognitive-manual attention required.

Interactive displays are becoming an integrated part of the modern vehicle environment. Their use typically entails dedicating a considerable amount of attention and undertaking a pointing gesture to select an interface item/icon displayed on a touchscreen. This can have serious safety implications for the driver. The pointing gesture can also be highly perturbed due to the road and driving conditions, resulting in erroneous selections. In this paper, we propose a probabilistic intent prediction approach that facilitates establishing the targeted icon on the interface early in the pointing gesture. It employs a 3D vision sensory device to continuously track the pointing hand/finger in conjunction with suitable Bayesian prediction algorithms. The introduced technique can significantly reduce the pointing task completion time, the necessary associated visual, cognitive and movement efforts as well as enhance the selection accuracy. The substantial furnished gains and the pointing gesture characteristics are demonstrated using data collected in an instrumented vehicle.

Sharing social and contextual information via services like Facebook, Twitter or Foursquare has become extremely popular in the recent years. This paper introduces the novel MyState concept in which users can augment any kind of object with Near Field Communication (NFC) tags, can write any social or contextual information on those tags using their mobile phones and can publish this information on a social networking site just by touching such a tag with their phone. The distinct features of MyState are A) the possibility to augment any personal or public object with any contextual or social information, B) the possibility that everybody can touch those tags in order to post the related information to a social networking site, C) the speed and convenience to publish information by a simple touch as users don't have to look at the mobile phone screen, interact with mobile phone menus or write any text when touching an already deployed tag. The paper reports on two field studies which provide insights on where the participants placed the tags, how they used MyState and what type of information was shared. Here we observed that users typically shared identity, location, activity and time, but also feelings, social meanings and experiences. Furthermore we identified several distinct social usage patterns such as synchronizing activities, expressing moods, games and tracking shared items.

This paper documents MultiKit: a toolkit that supports the development of sophisticated user-interfaces for applications using Near Field Communication (NFC). The usage of the toolkit is exemplified using three implemented prototypes, each with significant differences. These differences highlight the complexities involved in producing such NFC applications, and the benefits of a toolkit that can adapt to varying interface types. As the toolkit is tailored to NFC technology, NFC-specific features are explored. These include switching between dynamic (e.g. projection) and static interfaces (e.g. posters), and interface generation from NFC tag descriptions.

We introduce NaviRadar: an interaction technique for mobile phones that uses a radar metaphor in order to communicate the user's correct direction for crossings along a desired route. A radar sweep rotates clockwise and tactile feedback is provided where each sweep distinctly conveys the user's current direction and the direction in which the user must travel. In a first study, we evaluated the overall concept and tested five different tactile patterns to communicate the two different directions via a single tactor. The results show that people are able to easily understand the NaviRadar concept and can identify the correct direction with a mean deviation of 37° out of the full 360° provided. A second study shows that NaviRadar achieves similar results in terms of perceived usability and navigation performance when compared with spoken instructions. By using only tactile feedback, NaviRadar provides distinct advantages over current systems. In particular, no visual attention is required to navigate; thus, it can be spent on providing greater awareness of one's surroundings. Moreover, the lack of audio attention enables it to be used in noisy environments or this attention can be better spent on talking with others during navigation.

This paper reports on a development framework, two prototypes, and a comparative study in the area of multi-tag Near-Field Communication (NFC) interaction. By combining NFC with static and dynamic displays, such as posters and projections, services are made more visible and allow users to interact with them easily by interacting directly with the display with their phone. In this paper, we explore such interactions, in particular, the combination of the phone display and large NFC displays. We also compare static displays and dynamic displays, and present a list of deciding factors for a particular deployment situation. We discuss one prototype for each display type and developed a corresponding framework which can be used to accelerate the development of such prototypes whilst supporting a high level of versatility. The findings of a controlled comparative study indicate, among other things, that all participants preferred the dynamic display, although the static display has advantages, e.g. with respect to privacy and portability.

Important drawbacks of map-based navigation applications for mobile phones are their small screen size and that users have to associate the information provided by the mobile phone with the real word. Therefore, we designed, implemented and evaluated the Rotating Compass - a novel public display for pedestrian navigation. Here, a floor display continuously shows different directions (in a clockwise order) and the mobile phone informs the user when their desired direction is indicated. To inform the user, the mobile phone vibrates in synchronization with the indicated direction. We report an outdoor study that compares a conventional paper map, a navigation application running on a mobile device, navigation information provided by a public display, and the Rotating Compass. The results provide clear evidence of the advantages of the new interaction technique when considering task completion time, context switches, disorientation events, usability satisfaction, workload and multi-user support.

Exchanging data between a mobile phone and a computer such as a laptop is still a very cumbersome process. This paper presents two different techniques, touch & connect and touch & select, designed help to overcome this problem and facilitate and speed up spontaneous interactions between such devices. Using touch & connect, the user can physically touch a computer in order to pair a Bluetooth connection and initiate a file transfer between these two devices. Touch & select extends this concept in that users can select a specific object or location on the computer screen by simply touching it with the mobile phone. We report the implementation of these interaction techniques based on Near Field Communication (NFC) tags and present a formal, comparative study focusing on transferring images. The results provide clear evidence of the advantages of touch & connect and touch & select when compared with current Bluetooth-based implementations. Considering task completion time for uploading and downloading pictures, touch & select was 43% and touch & connect 31% faster than the conventional Bluetooth-based approach.

Uploading and downloading pictures between a mobile phone and a computer is still a very cumbersome process. Because of this, many users actually do not copy, move or backup their pictures onto another computer until the storage capacity of the mobile phone is reached. This paper presents the prototypes (and respective implementation details) of the touch & connect and touch & select interaction techniques. Both techniques allow the quick and easy exchange of pictures by touching the computer with the mobile device. The first interaction technique: touch & connect, allows the user to touch a computer with their mobile phone in order to establish a Bluetooth connection and initiate a file transfer between the two devices. The second interaction technique: touch & select, extends this concept and allows the selection of a specific picture or location on the computer screen by touching it with the mobile phone. The interaction techniques were implemented using Near Field Communication (NFC) tags attached to the computer and an NFC phone capable of reading those tags.

The limited screen size and resolution of current mobile devices can still be problematic for map, multimedia and browsing applications. In this paper we present Touch & Interact: an interaction technique in which a mobile phone is able to touch a display, at any position, to perform selections. Through the combination of the output capabilities of the mobile phone and display, applications can share the entire display space. Moreover, there is potential to realize new interaction techniques between the phone and display. For example, select & pick and select & drop are interactions whereby entities can be picked up onto the phone or dropped onto the display. We report the implementation of Touch & Interact, its usage for a tourist guide application and experimental comparison. The latter shows that the performance of Touch & Interact is comparable to approaches based on a touch screen; it also shows the advantages of our system regarding ease of use, intuitiveness and enjoyment.

Touch & Interact is an interaction technique which combines mobile phones and public displays. The motivation for the project is to overcome the intrinsic output limitations of mobile phones. Touch & Interact extends the phone output to a public display allowing both screens to share the display space. This concept is especially useful for separating public and private data -- only showing private data on the phone display. During interaction, the phone is used as a stylus for the public display and can touch the display at any location. The phone also lends additional capabilities to interactions by providing storage capabilities, additional feedback (e.g. audio and haptic) and input modalities (e.g. keypad and joystick). The underlying technology supporting Touch & Interact is Near Field Communication (NFC); the dynamic display includes a mesh of NFC tags which can be interacted with using an NFC phone. A tourist map application was used to explore and test Touch & Interact in an environment with rich functionality.