Green Citizen-Led Initiatives (GCLI) have been a long-standing research topic in the area of sustainable human-computer interaction with mixed success. In this paper, we present a larger investigation of the digital tools used by such initiatives in Denmark. We conducted semi-structured interviews with key people in 20 GCLI’s with different goals, sizes, and level of maturity. Our findings revealed that nearly all GCLIs relied mainly on standard tools that came with a variety of drawbacks and problems for them. Furthermore, we uncovered an ubiquitous platform paradox - the need to use Facebook to recruit and contact members despite the misalignment of their own and Facebook’s values - that seems hard to overcome. The challenges and directions outlined in this paper can guide future civic-tech work in this area to tackle common issues of multiple GCLIs and increase the impact of their work.

This paper examines the effects of eye-tracking-driven social gaze on the quality of communication in a virtual environment between two participants engaging in dyadic conversation in Virtual Reality (VR). While the importance of social gaze on quality of communication has been well documented, determining if its effects carry over into VR has not. This paper will outline the design and implementation of a multi-user VR experiment, focusing on developing the humanoid avatars and their gaze interactions and the findings of a comparative between-subjects study on three conditions: eye-tracking, without eye-tracking, and simulated gaze. The findings of this study indicate that for the specified implementation, eye-tracking-driven social gaze did not produce a statistically significant effect on the quality of conversation. However, it provided a more realistic conversation than a simulated social gaze.

Food waste in private households in industrialized countries is a growing concern. Inadequate food storage practices can lead to storing items in a way that leads to forgetting them until they become spoiled, increasing food waste. In this paper, we present FridgeSort, a serious mobile game that aims at teaching users how to sort their refrigerators with the underlying goal of reducing household food waste. The game was evaluated with 14 participants, and the results show that the participants were able to quickly learn the sorting method and recall it after an extended period of time. Overall, the results suggest that FridgeSort succeeded in teaching users how to sort a fridge that can be applied to the real world and lead to a reduction in food waste.

ECPlotter is a prototyping toolkit for the fabrication of electrochromic displays. By syringe depositing conductive, electrochromic and electrolyte inks, and curing the inks in one step, we can rapidly create displays in a single integrated process. In contrast to existing methods, such as screen-printing, ECPlotter allows for quick early prototyping with minimal human intervention and makes the process more accessible since the fabrication is automated. Our software pipeline enables designers to convert graphics directly into an instruction set that can be interpreted by the printer which includes automatic heat and UV curing passes after ink depositing. Finally, we demonstrate its capabilities by printing on a variety of substrates.

This course is a hands-on introduction to the fabrication of flexible, transparent free-form displays based on electrochromism for an audience with a variety of backgrounds, including artists and designers with no prior knowledge of physical prototyping. Besides prototyping using screen printing or ink-jet printing of electrochromic ink and an easy assembly process, participants will learn essentials for designing and controlling electrochromic displays.

Well-funded classrooms often provide a variety of learning materials such as computers, robotics and other expensive equipment to facilitate STEM Learning activities for children. However, exploring natural phenomena such as electrical energy is possible through very simple activities. In this paper we explore how cheap low-cost materials and simple electrochromic displays can be designed to support experiential learning about energy and power generation. For this we employed a mix of open-ended play and exploration as well as staged and goal-oriented activities. We developed two learning activities that involve children constructing working models that generate power including constructing a wind turbine and assembling a solar power harvesting house. We studied how children engaged in the activities and how the materials helped them understand the topic. All children could construct and complete the building tasks and were generally positive about the experience. We identified challenges encountered by children including interactions with the construction materials and electrochromic screens as well as insights about the mental models children have. We discuss challenges for staging learning through play with found low cost and local materials and provide implications for the design of constructionist oriented STEM learning.

Soft robotics - robots built from highly compliant materials that resemble soft biological materials - have recently become more popular especially in industry settings, given their ability to handle fragile objects. One problem however of these devices is that they can only communicate intend or the need for help through movement. To overcome this limitation, in this paper we present ChromaBot, a method towards prototyping soft robotic actuators with integrated printed electrochromic displays. Our method only degrades the longevity of the soft robotic actuator in an acceptable manner while at the same time allows for a more expressive soft robot. We present detailed instructions on how to prototype ChromaBot as well as an initial analysis of the durability, both of the display as well as of the actuator.

Consumer food waste in industrialised countries is becoming an increasing concern as its impact on greenhouse emissions is comparable to that of the aviation industry. In recent years we have accordingly seen a growing interest in HCI to support users getting into more sustainable consumption practices. As part of this movement, we present in this paper a serious game called Face-the-Waste that is meant to increase users food literacy and educate them about the impact and development of food waste. Our serious game comes in the form of a public installation that uses provocative design to engage the users. They had to answer multiple choice questions and if they answered wrongly real food would be disposed into a bin in front of the users eyes. The aim with this was to create a strong emotional response and increase the level of reflection on the topic. In our evaluation we not only found that the users often voiced very strong emotional reactions but also engaged and discussed the question and their content. Furthermore, we demonstrated that such provocations can add a new layer for the design of serious games.

VitaBoot is a footwear concept incorporating dynamic graphical patterns which indicate the wearer's activity level. Whilst shoes are an important element in fashion wear and a lot of research has focused on shoes as input devices, comparable few concepts have explored the potential for their use as an output space. We created a boot design that incorporates dynamic patterning through the use of electrochromic (EC) displays embedded in the surface material. The boot was designed and constructed from scratch, using a faux leather material, ensuring the overall aesthetic of the design, including the integration of the required control electronics and power source. The boot connects wirelessly to a chest-worn heart rate belt, and pattern changes indicate when the wearer's heart rate is above a predefined threshold. VitaBoot demonstrates the potential for dynamic shoe patterning for aesthetic or functional means, and the suitability of flexible, low-power EC display technology in this domain.

In today's world, radio waves are an integral element of our daily lives but they are mostly hidden to human perception. In this paper we present SKIN, a wireless wearable system that creates a new interface between the human and WiFi signals employing sensory augmentation. SKIN translates nearby WiFi data transmissions into a vibrotactile experi- ence to alter the perception of the space around the human body. It is designed as a tool for examining how an embod- ied experience of the invisible waves affects our relation to both the physical environment as well as to the technology emitting the insensible dimension. We present the design and implementation as well as the results of two exhibitions in which SKIN was worn by 17 participants that demon- strate how SKIN helps to interpret and alters the perception of the built environment.

The small display size of smartwatches creates a challenge for touch input, which is still the interaction technique of choice. Researchers and producers have started to investigate alternative interaction techniques. Apple and Samsung, for example, introduced digital versions of classic watch components such as the digital crown and the rotatable bezel. However, it remains an open question how well these components behave in terms of user interaction. Based on a self-built smartwatch prototype, we compare current interaction paradigms (touch input, rotatable bezel and digital crown) for one-dimensional tasks, i.e. scrolling in a list, two-dimensional tasks, i.e. navigation on a digital map, and a complex navigation/zoom task. To check for ecological validity of our results, we conducted an additional study focusing on interaction with currently available off-the-shelf devices using our considered interaction paradigms. Following our results, we present guidelines on which interaction techniques to use for the respective tasks.

While a variety of modalities and techniques have been explored to create feedback in gaming, thermal stimuli so far have been mostly neglected, even though they are an substantial part of the experience when interacting with real world objects. In this paper we investigate the use of thermal stimuli as a replacement for currently common feedback mechanisms such as visual or vibro-tactile for four different game mechanics. Instead of developing new game mechanics we opted to use already well established ones, namely Quick Time Events, Power Bars, Cooldowns and Area of Effect. Our evaluation with 13 participants indicate that for Quick Time Events and Area of Effect, thermal feedback is a valid replacement that could potentially pave the way for novel modalities in gaming.

Gaze is a powerful measure of people's attracted attention and reveals where we are looking within our current FOV. Hence gaze-based interfaces are gaining in importance. However, gaze estimation usually requires extensive hardware and depends on a calibration that has to be renewed regularly. We present EyeMirror, a mobile device for calibration-free gaze approximation on surfaces (e.g., displays). It consists of a head-mounted camera, connected to a wearable mini-computer, capturing the environment reflected on the human cornea. The corneal images are analyzed using natural feature tracking for gaze estimation on surfaces. In two lab studies we compared variations of EyeMirror against established methods for gaze estimation in a display scenario, and investigated the effect of display content (i.e. number of features). EyeMirror achieved 4.03° gaze estimation error, while we found no significant effect of display content.

Wearable sports devices like GPS watches and heart rate monitors are ubiquitous in sports like running or road cycling and enable the users to receive real-time performance feedback. Although rock climbing is a trending sport, there are little to no consumer electronics available to support rock climbing training during exercise. In this paper, we investigated the acceptance and appropriateness of wearables in climbing on different body parts. Based on an online survey with 54 climbers, we designed a wearable device and conducted a perception study with 12 participants in a climbing gym. Using vibro-tactile, audible, and visual cues while climbing an easy route and a hard route, requiring high physical and cognitive load, we found that the most suited notification channel is sound, directly followed by vibro-tactile output. Light has been found to be inappropriate for the use in the sport of climbing.

Practical wearable gesture tracking requires that sensors align with existing ergonomic device forms. We show that combining EMG and pressure data sensed only at the wrist can support accurate classification of hand gestures. A pilot study with unintended EMG electrode pressure variability led to exploration of the approach in greater depth. The EMPress technique senses both finger movements and rotations around the wrist and forearm, covering a wide range of gestures, with an overall 10-fold cross validation classification accuracy of 96%. We show that EMG is especially suited to sensing finger movements, that pressure is suited to sensing wrist and forearm rotations, and their combination is significantly more accurate for a range of gestures than either technique alone. The technique is well suited to existing wearable device forms such as smart watches that are already mounted on the wrist.

In this paper, we present WristRotate, a personalized motion gesture delimiter that enables separation of non-relevant motion from gesture input. In an extensive data collection, we acquired 435.1 hours of smartwatch acceleration data during everyday usage. We implemented a gesture recognition system based on Dynamic Time Warping to partition a stream of accelerometer readings to identify possible gestures and to classify them accordingly. Through our analysis, we were able to identify a gesture that is (1) uncommon in daily life; (2) quick and easy to execute and (3) easily and reliably detectable. The gesture is executed by simply rotating the lower arm and wrist outwards and back inwards (twice).

Nowadays, fans post status updates on social media that describe and express their opinion about live sports events. By doing this, they not only comment on the game but also provide information about the current state of play. In this paper we present TwitSoccer, a real-time live soccer score ticker crowd-sourced from tweets. TwitSoccer combines a pattern-based approach, to process the tweets, with a soccer knowledge-database. This allows to detect reoccurring events, such as goals or red cards, more precisely and ensures that these events are assigned to the right teams. The results of our evaluation for 42 soccer matches of the German Bundesliga, show that TwitSoccer automatically detects soccer events reliably with a recall value of 94% for goals and 71% for red cards which resembles a major enhancement over existing work.

Often, we operate mobile devices using only one hand. The hand thereby serves two purposes: holding the device and operating the touch screen with the thumb. The current trend of increasing screen sizes however, makes it close to impossible to reach all parts of the screen (especially the top area) for users with average hand sizes. One solution is to offer adaptive user interfaces for such one-handed interactions. These modes have to be triggered manually and thus induce a critical overhead. They are further designed to bring all content closer, regardless of whether the phone is operated with the left or right hand. In this paper, we present an algorithm that allows determining the users' interacting hand from their unlocking behavior. Our algorithm correctly distinguishes one- and two-handed usage as well as left- and right handed unlocking in 98.51% of all cases. This is achieved through a k-nearest neighbor comparison of the internal sensor readings of the smartphone during the unlocking process.

Our clothes are objects we interact with constantly. They represent our attitude and the circumstances we live in. In the following we will present an example of how this information can be used. Scarfy is a system based on a scarf which augments the natural interaction between a person and her clothes. Scarfy is able to detect the way it is tied and it can deliver information by shape-change and vibration. In this paper we explore the technical and fabrication approaches of technologically extended clothes and their input and output generation and discuss future applications.

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.

With the increasing availability of smartwatches the question of suited input modalities arises. While direct touch input comes at the cost of the fat-finger problem, we propose to use a dynamic peephole to explore larger content such as websites or maps. In this paper, we present the results of a user study comparing the performance of static and dynamic peephole interactions for a map navigation task on a smartwatch display. As a first method, we investigated the static peephole methaphor where the displayed map is moved on the device via direct touch interaction. In contrast, for the second method - the dynamic peephole - the device is moved and the map is static with respect to an external frame of reference. We compared both methods in terms of task performance and perceived user experience. The results show that the dynamic peephole interaction performs significantly more slowly in terms of task completion time.

With the recent increase in sales figures of tablet computers, a corresponding boost of mobile media consumption on such devices can be observed. Even though tablets provide a comparably larger screen in contrast to smartphones - which are taking the main share of mobile media consumption - the experience of consuming media content on tablets is still limited. For movie theatres the notion of 4 dimensional (4D) films exist, describing a 3D movie that is enhanced with ambient feedback such as environmental light, air streams or moist. In this paper we present ambiPad, a tablet prototype that enriches mobile digital media with ambient feedback around the tablet's display. Besides a light emitting frame, ambiPad allows for thermal stimuli as well. We report on the results of a qualitative user study, in which the feedback channels of ambiPad were rated as highly attractive and desirable by the participants.

We introduce the term shape resolution, which adds to the existing definitions of screen and touch resolution. We propose a framework, based on a geometric model (Non-Uniform Rational B-splines), which defines a metric for shape resolution in ten features. We illustrate it by comparing the current related work of shape changing devices. We then propose the concept of Morphees that are self-actuated flexible mobile devices adapting their shapes on their own to the context of use in order to offer better affordances. For instance, when a game is launched, the mobile device morphs into a console-like shape by curling two opposite edges to be better grasped with two hands. We then create preliminary prototypes of Morphees in order to explore six different building strategies using advanced shape changing materials (dielectric electro active polymers and shape memory alloys). By comparing the shape resolution of our prototypes, we generate insights to help designers toward creating high shape resolution Morphees.

Digital technologies are rapidly finding their way into urban spaces. One prominent example is media façades. Due to their size, visibility and their technical capabilities, they offer great potential for interaction and for becoming the future displays of public spaces. To explore their potential, researchers have recently started to develop interactive applications for various media façades. Existing development tools are mostly tailored to one specific media façade in one specific setting. They usually provide limited means to incorporate interaction by a user, and the applications developed are limited to running on only one particular media façade. In this paper, we present a flexible, generalized media façade toolkit, which is capable of mimicking arbitrary media façade installations. The toolkit is capable of running interactive applications on media façades with different form factors, sizes and technical capabilities. Furthermore, it ensures application portability between different media façades and offers the possibility of providing interactivity by enabling user input with different modalities and different interaction devices.

With the increasing adoption of smartphones also a problematic phenomena become apparent: People are changing their habits and become addicted to different services that these devices provide. In this paper we present AppDetox: an app that allows users to purposely create rules that keep them from using certain apps. We describe our deployment of the app on a mobile application store, and present initial findings gained through observation of about 11,700 users of the application. We find that people are rather rigorous when restricting their app use, and that mostly they suppress use of social networking and messaging apps.

With the recent trend of increasing display sizes of mobile devices, one-handed interaction has become increasingly difficult when a user wants to maintain a safe grip around the device at the same time. In this paper we evaluate how a combination of hybrid front- and back-of-device touch input can be used to overcome the difficulties when using a mobile device with one hand. Our evaluation shows that, even though such a technique is slower than conventional front-of-device input, it allows for accurate and safe input.

During sales conversations, gestures and mimics are of high importance to communicate information about a product. One prominent example for such sales gestures is the meat and cheese counter, which is one of the remaining spots in supermarkets where sales persons interact with customers. Interactions at such counters in supermarkets normally follow a simple protocol. The customer points at an item of choice. The employee takes out the item and, in most of the cases the product needs to be cut to fit the amount the customer wants to buy. Often it is ambiguous about what specific product the customer and the employees are talking about. Up to now, there are just a few efforts in HCI research to enrich communication at the point of sale. In this paper we report and analyze one scenario in which an intelligent natural user interface can support communication between customer and employee in a sales conversation. Furthermore, we report on our prototype that is able to track pointing gestures by using a depth camera and to display information about items pointed at.

We introduce spatially-aware virtual workspaces for the mobile environment. The notion of virtual workspaces was initially conceived to alleviate mental workload in desktop environments with limited display real-estate. Using spatial properties of mobile devices, we translate this approach and illustrate that mobile virtual workspaces greatly improve task performance for mobile devices. In a first study, we compare our spatially-aware prototype (mSpaces) to existing context switching methods for navigating amongst multiple tasks in the mobile environment. We show that users are faster, make more accurate decisions and require less mental and physical effort when using spatially-aware prototypes. We furthermore prototype pSpaces and m+pSpaces, two spatially-aware systems equipped with pico-projectors as auxiliary displays to provide dual-display capability to the handheld device. A final study reveals advantages of each of the different configurations and functionalities when comparing all three prototypes. Drawing on these findings, we identify design considerations to create, manipulate and manage spatially-aware virtual workspaces in the mobile environment.

Multi-touch interaction offers opportunities to interact with complex data. Especially the exploration of geographical data, which until today mostly relies on mice and keyboard input, could benefit from this interaction paradigm. However, the gestures that are required to interact with complex systems like Geographic Information Systems (GIS) increase in difficulty with every additional functionality. This paper describes a novel interaction approach that allows non-expert users to easily explore geographic data using a combination of multi-touch gestures and handpostures. The use of the additional input modality -- handpose -- is supposed to avoid more complex multi-touch gestures. Furthermore the screen of a wearable device serves as another output modality that on one hand avoids occlusion and on the other hand serves as a magic lens.

We present a flexible Machine Learning approach for learning user-specific touch input models to increase touch accuracy on mobile devices. The model is based on flexible, non-parametric Gaussian Process regression and is learned using recorded touch inputs. We demonstrate that significant touch accuracy improvements can be obtained when either raw sensor data is used as an input or when the device's reported touch location is used as an input, with the latter marginally outperforming the former. We show that learned offset functions are highly nonlinear and user-specific and that user-specific models outperform models trained on data pooled from several users. Crucially, significant performance improvements can be obtained with a small (≈200) number of training examples, easily obtained for a particular user through a calibration game or from keyboard entry data.

In this paper we investigate interaction with a media façade that is out of reach for touch-based interaction. We describe four different applications that utilize mobile devices to enable passers-by to interact with the façade. Each application has been designed constrained by limitations given by formal regulations of an editorial board (e.g. to prevent traffic distractions) and with the aim to catch the attention of passers-by to achieve interaction and keep the users engaged. Besides the description of the design and implementation of the different application, we report on initial feedback of users after a first preliminary user test that informs further development and design.

The workshop on mobile interaction in retail environments (MIRE) brings together researchers and practitioners from academy and industry to explore how mobile phones and mobile interaction can be embedded in retail environments to create new shopping experiences and mobile enhanced services.

Projector phones, handheld game consoles and many other mobile devices increasingly include more than one display, and therefore present a new breed of mobile Multi-Display Environments (MDEs) to users. Existing studies illustrate the effects of visual separation between displays in MDEs and suggest interaction techniques that mitigate these effects. Currently, mobile devices with heterogeneous displays such as projector phones are often designed without reference to visual separation issues; therefore it is critical to establish whether concerns and opportunities raised in the existing MDE literature apply to the emerging category of Mobile MDEs (MMDEs). This paper investigates the effects of visual separation in the context of MMDEs and contrasts these with fixed MDE results, and explores design factors for Mobile MDEs. Our study uses a novel eye-tracking methodology for measuring switches in visual context between displays and identifies that MMDEs offer increased design flexibility over traditional MDEs in terms of visual separation. We discuss these results and identify several design implications.

In many mid- to large-sized cities public maps are ubiquitous. One can also find a great number of maps in parks or near hiking trails. Public maps help to facilitate orientation and provide special information to not only tourists but also to locals who just want to look up an unfamiliar place while on the go. These maps offer many advantages compared to mobile maps from services like Google Maps Mobile or Nokia Maps. They often show local landmarks and sights that are not shown on standard digital maps. Often these 'You are here' (YAH) maps are adapted to a special use case, e.g. a zoo map or a hiking map of a certain area. Being designed for a fashioned purpose these maps are often aesthetically well designed and their usage is therefore more pleasant. In this paper we present a novel technique and application called PhotoMap that uses images of 'You are here' maps taken with a GPS-enhanced mobile camera phone as background maps for on-the-fly navigation tasks. We discuss different implementations of the main challenge, namely helping the user to properly georeference the taken image with sufficient accuracy to support pedestrian navigation tasks. We present a study that discusses the suitability of various public maps for this task and we evaluate if these georeferenced photos can be used for navigation on GPS-enabled devices.

Classic paper-based maps provide high-resolution, large-scale information and are ubiquitous in larger cities and even outdoors. In this paper we present a combination of their advantages with a mobile camera projector unit to create a new mobile and intuitive buddy finder interface. Current friend or buddy finder systems on mobile phones such as Google Latitude suffer from the small screen estate and display size of mobile devices. To overcome this problem we use a lightweight mobile camera projector unit to augment the paper map with a projected overlay of the buddies' positions. By using digital and geo-referenced representations of public maps no extra preperation for the tracking is needed. The idea is presented by enhancing Google Latitude, which allows users to browse the positions of their friends, to project the positions directly on the paper map without the cumbersome panning and zooming of a digital map on a small display.