This paper investigates the challenges of designing mixed-presence environments for Mixed Reality and suggests future research directions derived from an expert workshop. Developing mixed-presence systems is a complex undertaking that combines the intricacies of both co-located and distributed mixed-reality spaces. Current literature in this field describes various promising design and development approaches but lacks a systematic overview, resulting in fragmented solutions to re-occurring challenges. Therefore, we conducted a comprehensive review of mixed-presence and multi-user remote mixed-reality systems, categorizing the prevalent challenges faced during the development of such systems, but also current trends, common use cases, study tasks and methodologies. Supported by these results, we then conducted an expert ideation workshop to collect and structure promising future research directions. As a result, we provide a detailed resource to orient and prepare developers for probable challenges and support researchers in making informed design decisions for future mixed-presence studies in Mixed Reality.

This paper investigates associations, explicit representations of relations between multiple views in Mixed Reality (MR). While research on 2D desktop environments offers extensive recommendations for communicating relations between multiple views, MR environments lack such systematic guidance, necessitating adapted solutions that consider their spatial affordances. To address this gap, we systematically explored association techniques in existing research. Building on established 2D multi-view literature and refining insights from prior design principles, we developed a codebook to describe view relations and their representations. Applying it to a corpus of 44 immersive multi-view approaches, we identified recurring design strategies and synthesized them into a design space of visual association techniques adapted for immersive contexts. Based on a lightweight prototyping framework, we validate the utility of the design space through three envisioning scenarios, demonstrating how associations can support exploration, coordination, and sensemaking in MR applications. Our results inform the design of MR multi-view environments.

Abstract Multivariate line data is critical for analyzing flow fields, agent systems, and dynamic trajectories. Embedding secondary variables along spatial paths using surface‐based primitives such as ribbons and circular tubes introduces challenges related to perspective, scale, and distortion. Perceptual trade‐offs due to these challenges remain unclear. We address this gap through a controlled user study with 10 experts in computational fluid dynamics and visualization, performing four identical analysis tasks involving both spatial (requiring location‐based relationships) and non‐spatial (requiring attribute value comparisons) aspects. The tasks were performed using a prototype with interactivity limited to controlling the camera. While quantitative measures showed no significant performance differences between embedded visualizations on ribbons and tubes, we found a clear subjective preference for tubes among the study participants. Furthermore, their feedback indicates surface‐based embeddings are generally helpful and should be utilized more often.

We investigate hybrid user interfaces (HUIs), aiming to establish a cohesive understanding and to adopt consistent terminology for this nascent research area. HUIs combine heterogeneous devices in complementary roles, leveraging the distinct benefits of each. Our work focuses on cross-device interaction between 2D devices and mixed reality environments, which are particularly compelling, leveraging the familiarity of traditional 2D platforms while providing spatial awareness and immersion. Although prior work has prominently explored such HUIs in the context of mixed reality, we still lack a cohesive understanding of the unique design possibilities and challenges of such combinations, resulting in a fragmented research landscape. We conducted a systematic survey and present a taxonomy of HUIs that combine conventional display technology and mixed reality environments. Based on this, we discuss past and current challenges, the evolution of definitions, and prospective opportunities to tie together the past 30 years of research with our vision of future HUIs.

This paper investigates avatar self-views in virtual reality (VR) and their impact on multi-user communication scenarios. Self-views in video conferencing have been shown to impact our self-perception and mental load, so we explore whether similar effects occur in VR, as personal and professional gatherings progressively move to virtual spaces with 3D avatars. We identify the following key design dimensions for self-representations in VR: spatiality, anchoring and size, and self-visibility. Based on these, we designed three variants (Remote Perspective View, Personal Mirror, and Miniature Avatar), which we compare to a baseline (No Additional Self-View) in a user study. Our analysis of sixteen dyads playing a word-guessing game requiring verbal and non-verbal communication (i.e., explaining and charades) in VR confirms that self-views are beneficial for communication scenarios that require expressive body language or facial expressions, as this allows monitoring the own avatar's animations. Further, the Miniature Avatar was overall preferred due to its spatiality, world-anchoring, and full self-visibility. Based on our results, we offer design recommendations for self-views covering the key design dimensions in VR.

We investigate the concept of Augmented Dynamic Data Physicalization, the combination of shape-changing physical data representations with high-resolution virtual content. Tangible data sculptures, for example using mid-air shape-changing interfaces, are aesthetically appealing and persistent, but also technically and spatially limited. Blending them with Augmented Reality overlays such as scales, labels, or other contextual information opens up new possibilities. We explore the potential of this promising combination and propose a set of essential visualization components and interaction principles. They facilitate sophisticated hybrid data visualizations, for example Overview & Detail techniques or 3D view aggregations. We discuss three implemented applications that demonstrate how our approach can be used for personal information hubs, interactive exhibitions, and immersive data analytics. Based on these use cases, we conducted hands-on sessions with external experts, resulting in valuable feedback and insights. They highlight the potential of combining dynamic physicalizations with dynamic AR overlays to create rich and engaging data experiences.

In recent years, data-driven stories have found a firm footing in journalism, business, and education. They leverage visualization and storytelling to convey information to broader audiences. Likewise, immersive technologies, like augmented and virtual reality devices, provide excellent potential for exploring and explaining data, thus inviting research on how data-driven storytelling transfers to immersive environments. To gain a better understanding of this exciting novel research area, we conducted a scoping review on the emerging notion of immersive data-driven storytelling, extended by surveying immersive data journalism and by analyzing immersive games, selected based on community reviews and tags. We present our methodology for the survey and discuss prominent themes that coalesce the knowledge we extracted from the literature, journalism, and games. These themes include, among others, the spatial embodiment of narration, the incorporation of the users and their context into narratives, and the balance between guiding the user versus promoting serendipity. Our discussion of these themes reveals research opportunities and challenges that will inform the design of immersive data-driven stories in the future.

Abstract In the past few years, large high‐resolution displays (LHRDs) have attracted considerable attention from researchers, industries and application areas that increasingly rely on data‐driven decision‐making. An up‐to‐date survey on the use of LHRDs for interactive data visualization seems warranted to summarize how new solutions meet the characteristics and requirements of LHRDs and take advantage of their unique benefits. In this survey, we start by defining LHRDs and outlining the consequence of LHRD environments on interactive visualizations in terms of more pixels, space, users and devices. Then, we review related literature along the four axes of visualization, interaction, evaluation studies and applications. With these four axes, our survey provides a unique perspective and covers a broad range of aspects being relevant when developing interactive visual data analysis solutions for LHRDs. We conclude this survey by reflecting on a number of opportunities for future research to help the community take up the still‐open challenges of interactive visualization on LHRDs.

Videoconferencing has become a ubiquitous medium for collaborative work. It does suffer however from various drawbacks such as zoom fatigue. This paper addresses the quality of user experience by exploring an enhanced system concept with the capability of conveying gaze and attention. Gazing Heads is a round-table virtual meeting concept that uses only a single screen per participant. It enables direct eye contact, and signals gaze via controlled head rotation. The technology to realise this novel concept is not quite mature though, so we built a camera-based simulation for four simultaneous videoconference users. We conducted a user study comparing Gazing Heads with a conventional “Tiled View” video conferencing system, for 20 groups of 4 people, on each of two tasks. The study found that head rotation clearly conveys gaze and strongly enhances the perception of attention. Measurements of turn-taking behaviour did not differ decisively between the two systems (though there were significant differences between the two tasks). A novel insight in comparison to prior studies is that there was a significant increase in mutual eye contact with Gazing Heads, and that users clearly felt more engaged, encouraged to participate and more socially present. Overall, participants expressed a clear preference for Gazing Heads. These results suggest that fully implementing the Gazing Heads concept, using modern computer vision technology as it matures, could significantly enhance the experience of videoconferencing.

This paper presents Pearl, a mixed-reality approach for the analysis of human movement data in situ. As the physical environment shapes human motion and behavior, the analysis of such motion can benefit from the direct inclusion of the environment in the analytical process. We present methods for exploring movement data in relation to surrounding regions of interest, such as objects, furniture, and architectural elements. We introduce concepts for selecting and filtering data through direct interaction with the environment, and a suite of visualizations for revealing aggregated and emergent spatial and temporal relations. More sophisticated analysis is supported through complex queries comprising multiple regions of interest. To illustrate the potential of Pearl, we developed an Augmented Reality-based prototype and conducted expert review sessions and scenario walkthroughs in a simulated exhibition. Our contribution lays the foundation for leveraging the physical environment in the in-situ analysis of movement data.

Abstract State-of-the-art Probabilistic Model Checking (PMC) offers multiple engines for the quantitative analysis of Markov Decision Processes (MDPs), including rewards modeling cost or utility values. Despite the huge amount of internally computed information, support for debugging and facilities that enhance the understandability of PMC models and results are very limited. As a first step to improve on that, we present the basic principles of PMC-VIS, a tool that supports the exploration of large MDPs together with the computed PMC results per MDP-state through interactive visualization. By combining visualization techniques, such as node-link diagrams and parallel coordinates, with quantitative analysis capabilities, PMC-VIS supports users in gaining insights into the probabilistic behavior of MDPs and PMC results and enables different ways to explore the behaviour of schedulers of multiple target properties. The usefulness of PMC-VIS is demonstrated through three different application scenarios.

Abstract OWL is a powerful language to formalize terminologies in an ontology. Its main strength lies in its foundation on description logics, allowing systems to automatically deduce implicit information through logical reasoning. However, since ontologies are often complex, understanding the outcome of the reasoning process is not always straightforward. Unlike already existing tools for exploring ontologies, our visualization tool Evonne is tailored towards explaining logical consequences. In addition, it supports the debugging of unwanted consequences and allows for an interactive comparison of the impact of removing statements from the ontology. Our visual approach combines (1) specialized views for the explanation of logical consequences and the structure of the ontology, (2) employing multiple layout modes for iteratively exploring explanations, (3) detailed explanations of specific reasoning steps, (4) cross‐view highlighting and colour coding of the visualization components, (5) features for dealing with visual complexity and (6) comparison and exploration of possible fixes to the ontology. We evaluated Evonne in a qualitative study with 16 experts in logics, and their positive feedback confirms the value of our concepts for explaining reasoning and debugging ontologies.

We developed and validated a rating scale to assess the aesthetic pleasure (or beauty) of a visual data representation: the BeauVis scale. With our work we offer researchers and practitioners a simple instrument to compare the visual appearance of different visualizations, unrelated to data or context of use. Our rating scale can, for example, be used to accompany results from controlled experiments or be used as informative data points during in-depth qualitative studies. Given the lack of an aesthetic pleasure scale dedicated to visualizations, researchers have mostly chosen their own terms to study or compare the aesthetic pleasure of visualizations. Yet, many terms are possible and currently no clear guidance on their effectiveness regarding the judgment of aesthetic pleasure exists. To solve this problem, we engaged in a multi-step research process to develop the first validated rating scale specifically for judging the aesthetic pleasure of a visualization (osf.io/fxs76). Our final BeauVis scale consists of five items, "enjoyable," "likable," "pleasing," "nice," and "appealing." Beyond this scale itself, we contribute (a) a systematic review of the terms used in past research to capture aesthetics, (b) an investigation with visualization experts who suggested terms to use for judging the aesthetic pleasure of a visualization, and (c) a confirmatory survey in which we used our terms to study the aesthetic pleasure of a set of 3 visualizations.

Stylized tubes are an established visualization primitive for line data as encountered in many scientific fields, ranging from characteristic lines in flow fields, fiber tracks reconstructed from diffusion tensor imaging, to trajectories of moving objects as they arise from cyber-physical systems in many engineering disciplines. Typical challenges include large data set sizes demanding for efficient rendering techniques as well as a large number of attributes that cannot be mapped simultaneously to the basic visual attributes provided by a tube-based visualization. In this work, we tackle both challenges with a new on-tube visualization approach. We improve recent work on high-quality GPU ray casting of Hermite spline tubes supporting ambient occlusion and extend it by a new layered procedural texturing technique. In the proposed framework, a large number of data set attributes can be mapped simultaneously to a variety of glyphs and plots that are embedded in texture space and organized in layers. Efficient rendering with minimal data transfer is achieved by generating the glyphs procedurally and drawing them in a deferred shading pass. We integrated these techniques in a prototype visualization tool that facilitates flexible mapping of data set attributes to visual tube and glyph attributes. We studied our approach on a variety of example data from different fields and found it to provide a highly adaptable and extensible toolbox to quickly craft tailor-made tube-based trajectory visualizations.

Abstract Hyperproperties relate multiple computation traces to each other. Model checkers for hyperproperties thus return, in case a system model violates the specification, a set of traces as a counterexample. Fixing the erroneous relations between traces in the system that led to the counterexample is a difficult manual effort that highly benefits from additional explanations. In this paper, we present an explanation method for counterexamples to hyperproperties described in the specification logic HyperLTL. We extend Halpern and Pearl’s definition of actual causality to sets of traces witnessing the violation of a HyperLTL formula, which allows us to identify the events that caused the violation. We report on the implementation of our method and show that it significantly improves on previous approaches for analyzing counterexamples returned by HyperLTL model checkers.

We present STRAIDE, a string-actuated interactive display environment that allows to explore the promising potential of shape-changing interfaces for casual visualizations. At the core, we envision a platform that spatially levitates elements to create dynamic visual shapes in space. We conceptualize this type of tangible mid-air display and discuss its multifaceted design dimensions. Through a design exploration, we realize a physical research platform with adjustable parameters and modular components. For conveniently designing and implementing novel applications, we provide developer tools ranging from graphical emulators to in-situ augmented reality representations. To demonstrate STRAIDE’s reconfigurability, we further introduce three representative physical setups as a basis for situated applications including ambient notifications, personal smart home controls, and entertainment. They serve as a technical validation, lay the foundations for a discussion with developers that provided valuable insights, and encourage ideas for future usage of this type of appealing interactive installation.

Future offices are likely reshaped by Augmented Reality (AR) extending the display space while maintaining awareness of surroundings, and thus promise to support collaborative tasks such as brainstorming or sensemaking. However, it is unclear how physical surroundings and co-located collaboration influence the spatial organization of virtual content for sensemaking. Therefore, we conducted a study (N=28) to investigate the effect of office environments and work styles during a document classification task using AR with regard to content placement, layout strategies, and sensemaking workflows. Results show that participants require furniture, especially tables and whiteboards, to assist sensemaking and collaboration regardless of room settings, while generous free spaces (e.g., walls) are likely used when available. Moreover, collaborating participants tend to use furniture despite personal layout preferences. We identified different placement and layout strategies, as well as the transitions in-between. Finally, we propose design implications for future immersive sensemaking applications and beyond.

Analysis of human motion data can reveal valuable insights about the utilization of space and interaction of humans with their environment. To support this, we present AvatAR, an immersive analysis environment for the in-situ visualization of human motion data, that combines 3D trajectories with virtual avatars showing people’s detailed movement and posture. Additionally, we describe how visualizations can be embedded directly into the environment, showing what a person looked at or what surfaces they touched, and how the avatar’s body parts can be used to access and manipulate those visualizations. AvatAR combines an AR HMD with a tablet to provide both mid-air and touch interaction for system control, as well as an additional overview device to help users navigate the environment. We implemented a prototype and present several scenarios to show that AvatAR can enhance the analysis of human motion data by making data not only explorable, but experienceable.

Recent developments on solvers for abstract argumentation frameworks (AFs) made them capable to compute extensions for many semantics efficiently. However, for many input instances these solution spaces can become very large and incomprehensible. So far, for the further exploration and investigation of the AF solution space the user needs to use post-processing methods or handcrafted tools. To compare and explore the solution spaces of two selected semantics, we propose an approach that visually supports the user, via a combination of dimensionality reduction of argumentation extensions and a projection of extensions to sets of accepted or rejected arguments. We introduce the novel web-based visualization tool NEXAS that allows for an interactive exploration of the solution space together with a statistical analysis of the acceptance of individual arguments for the selected semantics, as well as provides an interactive correlation matrix for the acceptance of arguments. We validate the tool with a walk-through along three use cases.

In this paper, we examine the potential of incorporating transparent, handheld devices into head-mounted Augmented Reality (AR). Additional mobile devices have long been successfully used in head-mounted AR, but they obscure the visual context and real world objects during interaction. Transparent tangible displays can address this problem, using either transparent OLED screens or rendering by the head-mounted display itself. However, so far, there is no systematic analysis of the use of such transparent tablets in combination with AR head-mounted displays (HMDs), with respect to their benefits and arising challenges. We address this gap by introducing a research platform based on a touch-enabled, transparent interaction panel, for which we present our custom hardware design and software stack in detail. Furthermore, we developed a series of interaction concepts for this platform and demonstrate them in the context of three use case scenarios: the exploration of 3D volumetric data, collaborative visual data analysis, and the control of smart home appliances. We validate the feasibility of our concepts with interactive prototypes that we used to elicit feedback from HCI experts. As a result, we contribute to a better understanding of how transparent tablets can be integrated into future AR environments.

Augmented Reality (AR) interfaces support users by providing access to digital content within real-world environments. However, displaying content at the users’ eye level might result in the occlusion of the real world. Therefore, it requires finding AR content placement areas that free the users’ field of vision. In this work, we systematically investigate two content placement areas beyond the users’ eye level: the ceiling and floor. To understand how potential users perceive virtual content on the ceiling and floor and how the content should be placed on these areas, we conducted two user studies. While the first exploratory study showed the general usefulness of either area, the second quantitative study allowed us to define optimal placement parameters regarding visibility and comfort. With insights from our studies, we provide design recommendations for future AR applications that support 2D content presentation on the ceiling and the floor.

Model checkers provide algorithms for proving that a mathematical model of a system satisfies a given specification. In case of a violation, a counterexample that shows the erroneous behavior is returned. Understanding these counterexamples is challenging, especially for hyperproperty specifications, i.e., specifications that relate multiple executions of a system to each other. We aim to facilitate the visual analysis of such counterexamples through our HyperVis tool, which provides interactive visualizations of the given model, specification, and counterexample. Within an iterative and interdisciplinary design process, we developed visualization solutions that can effectively communicate the core aspects of the model checking result. Specifically, we introduce graphical representations of binary values for improving pattern recognition, color encoding for better indicating related aspects, visually enhanced textual descriptions, as well as extensive cross-view highlighting mechanisms. Further, through an underlying causal analysis of the counterexample, we are also able to identify values that contributed to the violation and use this knowledge for both improved encoding and highlighting. Finally, the analyst can modify both the specification of the hyperproperty and the system directly within HyperVis and initiate the model checking of the new version. In combination, these features notably support the analyst in understanding the error leading to the counterexample as well as iterating the provided system and specification. We ran multiple case studies with HyperVis and tested it with domain experts in qualitative feedback sessions. The participants' positive feedback confirms the considerable improvement over the manual, text-based status quo and the value of the tool for explaining hyperproperties.

In this paper, we present MIRIA, a Mixed Reality Interaction Analysis toolkit designed to support the in-situ visual analysis of user interaction in mixed reality and multi-display environments. So far, there are few options to effectively explore and analyze interaction patterns in such novel computing systems. With MIRIA, we address this gap by supporting the analysis of user movement, spatial interaction, and event data by multiple, co-located users directly in the original environment. Based on our own experiences and an analysis of the typical data, tasks, and visualizations used in existing approaches, we identify requirements for our system. We report on the design and prototypical implementation of MIRIA, which is informed by these requirements and offers various visualizations such as 3D movement trajectories, position heatmaps, and scatterplots. To demonstrate the value of MIRIA for real-world analysis tasks, we conducted expert feedback sessions using several use cases with authentic study data.

We present Marvis, a conceptual framework that combines mobile devices and head-mounted Augmented Reality (AR) for visual data analysis. We propose novel concepts and techniques addressing visualization-specific challenges. By showing additional 2D and 3D information around and above displays, we extend their limited screen space. AR views between displays as well as linking and brushing are also supported, making relationships between separated visualizations plausible. We introduce the design process and rationale for our techniques. To validate Marvis’ concepts and show their versatility and widespread applicability, we describe six implemented example use cases. Finally, we discuss insights from expert hands-on reviews. As a result, we contribute to a better understanding of how the combination of one or more mobile devices with AR can benefit visual data analysis. By exploring this new type of visualization environment, we hope to provide a foundation and inspiration for future mobile data visualizations.

In this work we report on two comprehensive user studies investigating the perception of Augmented Reality (AR) visualizations influenced by real-world backgrounds. Since AR is an emerging technology, it is important to also consider productive use cases, which is why we chose an exemplary and challenging industry 4.0 environment. Our basic perceptual research focuses on both the visual complexity of backgrounds as well as the influence of a secondary task. In contrast to our expectation, data of our 34 study participants indicate that the background has far less influence on the perception of AR visualizations. Moreover, we observed a mismatch between measured and subjectively reported performance. We discuss the importance of the background and recommendations for visual real-world augmentations. Overall, our results suggest that AR can be used in many visually challenging environments without losing the ability to productively work with the visualizations shown.

Matrix visualizations are a useful tool to provide a general overview of a graph's structure. For multivariate graphs, a remaining challenge is to cope with the attributes that are associated with nodes and edges. Addressing this challenge, we propose responsive matrix cells as a focus+context approach for embedding additional interactive views into a matrix. Responsive matrix cells are local zoomable regions of interest that provide auxiliary data exploration and editing facilities for multivariate graphs. They behave responsively by adapting their visual contents to the cell location, the available display space, and the user task. Responsive matrix cells enable users to reveal details about the graph, compare node and edge attributes, and edit data values directly in a matrix without resorting to external views or tools. We report the general design considerations for responsive matrix cells covering the visual and interactive means necessary to support a seamless data exploration and editing. Responsive matrix cells have been implemented in a web-based prototype based on which we demonstrate the utility of our approach. We describe a walk-through for the use case of analyzing a graph of soccer players and report on insights from a preliminary user feedback session.

In this work we propose the combination of large interactive displays with personal head-mounted Augmented Reality (AR) for information visualization to facilitate data exploration and analysis. Even though large displays provide more display space, they are challenging with regard to perception, effective multi-user support, and managing data density and complexity. To address these issues and illustrate our proposed setup, we contribute an extensive design space comprising first, the spatial alignment of display, visualizations, and objects in AR space. Next, we discuss which parts of a visualization can be augmented. Finally, we analyze how AR can be used to display personal views in order to show additional information and to minimize the mutual disturbance of data analysts. Based on this conceptual foundation, we present a number of exemplary techniques for extending visualizations with AR and discuss their relation to our design space. We further describe how these techniques address typical visualization problems that we have identified during our literature research. To examine our concepts, we introduce a generic AR visualization framework as well as a prototype implementing several example techniques. In order to demonstrate their potential, we further present a use case walkthrough in which we analyze a movie data set. From these experiences, we conclude that the contributed techniques can be useful in exploring and understanding multivariate data. We are convinced that the extension of large displays with AR for information visualization has a great potential for data analysis and sense-making.

Rapid prototyping of interactive textiles is still challenging, since manual skills, several processing steps, and expert knowledge are involved. We present Rapid Iron-On User Interfaces, a novel fabrication approach for empowering designers and makers to enhance fabrics with interactive functionalities. It builds on heat-activated adhesive materials consisting of smart textiles and printed electronics, which can be flexibly ironed onto the fabric to create custom interface functionality. To support rapid fabrication in a sketching-like fashion, we developed a handheld dispenser tool for directly applying continuous functional tapes of desired length as well as discrete patches. We introduce versatile compositions techniques that allow for creating complex circuits, utilizing commodity textile accessories and sketching custom-shaped I/O modules. We further contribute a comprehensive library of components for input, output, wiring and computing. Three example applications, results from technical experiments and expert reviews demonstrate the functionality, versatility and potential of this approach.

While smartwatches are widely adopted these days, their input and output space remains fairly limited by their screen size. We present StrapDisplays-interactive watchbands with embedded display and touch technologies-that enhance commodity watches and extend their input and output capabilities. After introducing the physical design space of these StrapDisplays, we explore how to combine a smartwatch and straps in a synergistic Watch+Strap system. Specifically, we propose multiple interface concepts that consider promising content distributions, interaction techniques, usage types, and display roles. For example, the straps can enrich watch apps, display visualizations, provide glanceable feedback, or help avoiding occlusion issues. Further, we provide a modular research platform incorporating three StrapDisplay prototypes and a flexible web-based software architecture, demonstrating the feasibility of our approach. Early brainstorming sessions with 15 participants informed our design process, while later interviews with six experts supported our concepts and provided valuable feedback for future developments.

We present Vistribute, a framework for the automatic distribution of visualizations and UI components across multiple heterogeneous devices. Our framework consists of three parts: (i) a design space considering properties and relationships of interactive visualizations, devices, and user preferences in multi-display environments; (ii) specific heuristics incorporating these dimensions for guiding the distribution for a given interface and device ensemble; and (iii) a web-based implementation instantiating these heuristics to automatically generate a distribution as well as providing interaction mechanisms for user-defined adaptations. In contrast to existing UI distribution systems, we are able to infer all required information by analyzing the visualizations and devices without relying on additional input provided by users or programmers. In a qualitative study, we let experts create their own distributions and rate both other manual distributions and our automatic ones. We found that all distributions provided comparable quality, hence validating our framework.

In this paper, we investigate mobile devices as interactive controllers to support the exploration of 3D data spaces in head-mounted Augmented Reality (AR). In future mobile contexts, applications such as immersive analysis or ubiquitous information retrieval will involve large 3D data sets, which must be visualized in limited physical space. This necessitates efficient interaction techniques for 3D panning and zooming. Smartphones as additional input devices are promising because they are familiar and widely available in mobile usage contexts. They also allow more casual and discreet interaction compared to free-hand gestures or voice input. We introduce smartphone-based pan & zoom techniques for 3D data spaces and present a user study comparing five techniques. Our results show that spatial device gestures can outperform both touch-based techniques and hand gestures in terms of task completion times and user preference. We discuss our findings in detail and suggest suitable techniques for specific AR navigation tasks.

We present DesignAR, an augmented design workstation for creating 3D models. Our approach seamlessly integrates an interactive surface displaying 2D views with head-mounted, stereoscopic Augmented Reality (AR). This creates a combined output space that expands the screen estate and enables placing 3D objects beyond display borders. For the effective combination of 2D and 3D views, we define different levels of proximity and alignment. Regarding input, multi-touch and pen mitigate issues of precision and ergonomics commonly found in mid-air VR/AR interaction. For creating and refining 3D models, we propose a set of pen and touch techniques with immediate AR feedback, including sketching of rotational solids or tracing physical objects on the surface. To further support a designer's modeling process, we additionally propose orthographic model views and UI offloading in AR as well as freely placeable model instances with real-world reference. Based on our DesignAR prototype, we report on challenges and insights regarding this novel type of display augmentation. The combination of high-resolution, high-precision interactive surfaces with carefully aligned AR views opens up exciting possibilities for future work and design environments, a vision we call Augmented Displays.

Interactive wall-sized displays benefit data visualization. Due to their sheer display size, they make it possible to show large amounts of data in multiple coordinated views (MCV) and facilitate collaborative data analysis. In this work, we propose a set of important design considerations and contribute a fundamental input vocabulary and interaction mapping for MCV functionality. We also developed a fully functional application with more than 45 coordinated views visualizing a real-world, multivariate data set of crime activities, which we used in a comprehensive qualitative user study investigating how pairs of users behave. Most importantly, we found that flexible movement is essential and-depending on user goals-is connected to collaboration, perception, and interaction. Therefore, we argue that for future systems interaction from the distance is required and needs good support. We show that our consistent design for both direct touch at the large display and distant interaction using mobile phones enables the seamless exploration of large-scale MCV at wall-sized displays. Our MCV application builds on design aspects such as simplicity, flexibility, and visual consistency and, therefore, supports realistic workflows. We believe that in the future, many visual data analysis scenarios will benefit from wall-sized displays presenting numerous coordinated visualizations, for which our findings provide a valuable foundation.

We demonstrate the prototype of the conceptual VisTiles framework. VisTiles allows exploring multivariate data sets by using multiple coordinated views that are distributed across a set of mobile devices. This setup allows users to benefit from dynamic and user-defined interface arrangements and to easily initiate co-located data exploration sessions. The current web-based prototype runs on commodity devices and is able to determine the spatial device arrangement by either a cross-device pinch gesture or an external tracking system. Multiple data sets are provided that can be explored by different visualizations (e.g., scatterplots, parallel coordinate plots, stream graphs). With this demonstration, we showcase the general concepts of VisTiles and discuss ideas for enhancements as well the potential for application cases beyond data analysis.

We explore the combination of smartwatches and a large interactive display to support visual data analysis. These two extremes of interactive surfaces are increasingly popular, but feature different characteristics-display and input modalities, personal/public use, performance, and portability. In this paper, we first identify possible roles for both devices and the interplay between them through an example scenario. We then propose a conceptual framework to enable analysts to explore data items, track interaction histories, and alter visualization configurations through mechanisms using both devices in combination. We validate an implementation of our framework through a formative evaluation and a user study. The results show that this device combination, compared to just a large display, allows users to develop complex insights more fluidly by leveraging the roles of the two devices. Finally, we report on the interaction patterns and interplay between the devices for visual exploration as observed during our study.

Today, the widespread use of mobile devices allows users to search information "on the go»», whenever and wherever they want, no longer confining Information Retrieval to classic desktop interfaces. We believe that technical advances in Augmented Reality will allow Information Retrieval to go even further, making use of both the users» surroundings and their abilities to interact with the physical world. In this paper, we present the fundamental concept of Reality-Based Information Retrieval, which combines the classic Information Retrieval process with Augmented Reality technologies to provide context-dependent search cues and situated visualizations of the query and the results. With information needs often stemming from real-world experiences, this novel combination has the potential to better support both Just-in-time Information Retrieval and serendipity. Based on extensive literature research, we propose a conceptual framework for Reality-Based Information Retrieval. We illustrate and discuss this framework and present two prototypical implementations, which we tested in small user studies. They demonstrate the feasibility of our concepts and inspired our discussion of notable challenges for further research in this novel and promising area.

We present VISTILES, a conceptual framework that uses a set of mobile devices to distribute and coordinate visualization views for the exploration of multivariate data. In contrast to desktop-based interfaces for information visualization, mobile devices offer the potential to provide a dynamic and user-defined interface supporting co-located collaborative data exploration with different individual workflows. As part of our framework, we contribute concepts that enable users to interact with coordinated & multiple views (CMV) that are distributed across several mobile devices. The major components of the framework are: (i) dynamic and flexible layouts for CMV focusing on the distribution of views and (ii) an interaction concept for smart adaptations and combinations of visualizations utilizing explicit side-by-side arrangements of devices. As a result, users can benefit from the possibility to combine devices and organize them in meaningful spatial layouts. Furthermore, we present a web-based prototype implementation as a specific instance of our concepts. This implementation provides a practical application case enabling users to explore a multivariate data collection. We also illustrate the design process including feedback from a preliminary user study, which informed the design of both the concepts and the final prototype.

Due to their simplicity and flexibility, digital pen-and-paper solutions have a promising potential to become a part of our daily work. Unfortunately, they lack dynamic visual feedback and thereby restrain advanced digital functionalities. In this paper, we investigate new forms of paper-integrated feedback, which build on emerging paper-based electronics and novel thin-film display technologies. Our approach focuses on illuminated elements, which are seamlessly integrated into standard paper. For that, we introduce an extended design space for paper-integrated illuminations. As a major contribution, we present a systematic feedback repertoire for real-world applications including feedback components for innovative paper interaction tasks in five categories. Furthermore, we contribute a fully-functional research platform including a paper-controller, digital pen and illuminated, digitally controlled papers that demonstrate the feasibility of our techniques. Finally, we report on six interviews, where experts rated our approach as intuitive and very usable for various applications, in particular educational ones.

Large interactive displays are increasingly important and a relevant research topic, and several studies have focused on wall interaction. However, in many cases, thorough user studies currently require time-consuming video analysis and coding. We present the Group Interaction Analysis Toolkit GIAnT, which provides a rich set of visualizations supporting investigation of multi-user interaction at large display walls. GIAnT focuses on visualizing time periods, making it possible to gain overview-level insights quickly. The toolkit is designed to be extensible and features several carefully crafted visualizations: A novel timeline visualization shows movement in front of the wall over time, a wall visualization shows interactions on the wall and gaze data, and a floor visualization displays user positions. In addition, GIAnT shows the captured video stream along with basic statistics. We validate our tool by analyzing how it supports investigating major research topics and by practical use in evaluating a cooperative game.

In order to realize zero-effort retrieval in a web-context, it is crucial to identify the part of the web page the user is focusing on. In this paper, we investigate the identification of focus paragraphs in web pages. Starting from a naive baseline for paragraph and focus paragraph detection, we conducted an eye-tracking study to evaluate the most promising features. We found that single features (mouse position, paragraph position, mouse activity) are less predictive for gaze which confirms findings from other studies. The results indicate that an algorithm for focus paragraph detection needs to incorporate a weighted combination of those features as well as additional features, e.g. semantic context derived from the user's web history.

Three-dimensional visualizations employing traditional input and output technologies have well-known limitations. Immersive technologies, natural interaction techniques, and recent developments in data physicalization may help to overcome these issues. In this context, we are specifically interested in the usage of spatial interaction with mobile devices for improved 3D visualizations. To contribute to a better understanding of this interaction style, we implemented example visualizations on a spatially-tracked tablet and investigated their usage and potential. In this paper, we report on a qualitative study comparing spatial interaction with inplace 3D visualizations to classic touch interaction regarding typical visualization tasks: navigation of unknown datasets, comparison of individual data objects, and the understanding and memorization of structures in the data. We identify several distinct usage patterns and derive recommendations for using spatial interaction in 3D data visualization.

In this paper, we demonstrate IllumiPaper: a system that provides new forms of paper-integrated visual feedback and enables multiple input channels to enhance digital paper applications. We aim to take advantage of traditional form sheets, including their haptic qualities, simplicity, and archivability, and simultaneously integrate rich digital functionalities such as dynamic status queries, real-time notifications, and visual feedback for widget controls. Our approach builds on emerging, novel paper-based technologies. We describe a fabrication process that allow us to directly integrate segment-based displays, touch and flex sensors, as well as digital pen input on the paper itself. With our fully functional research platform we demonstrate an interactive prototype for an industrial form-filling maintenance application to service computer networks that covers a wide range of typical paper-related tasks.

Tabletop interaction can be enriched by considering whole hands as input instead of only fingertips. We describe a generalised, reproducible computer vision algorithm to recognise hand contact shapes, with support for arm rejection, as well as dynamic properties like finger movement and hover. A controlled experiment shows the algorithm can detect seven different contact shapes with roughly 91% average accuracy. The effect of long sleeves and non-user specific templates is also explored. The algorithm is used to trigger, parameterise, and dynamically control menu and tool widgets, and the usability of a subset of these are qualitatively evaluated in a realistic application. Based on our findings, we formulate a number of design recommendations for hand shape-based interaction.

Abstract Going beyond established desktop interfaces, researchers have begun re‐thinking visualization approaches to make use of alternative display environments and more natural interaction modalities. In this paper, we investigate how spatially‐aware mobile displays and a large display wall can be coupled to support graph visualization and interaction. For that purpose, we distribute typical visualization views of classic node‐link and matrix representations between displays. The focus of our work lies in novel interaction techniques that enable users to work with personal mobile devices in combination with the wall. We devised and implemented a comprehensive interaction repertoire that supports basic and advanced graph exploration and manipulation tasks, including selection, details‐on‐demand, focus transitions, interactive lenses, and data editing. A qualitative study has been conducted to identify strengths and weaknesses of our techniques. Feedback showed that combining mobile devices and a wall‐sized display is useful for diverse graph‐related tasks. We also gained valuable insights regarding the distribution of visualization views and interactive tools among the combined displays.

Abstract The elegance of using virtual interactive lenses to provide alternative visual representations for selected regions of interest is highly valued, especially in the realm of visualization. Today, more than 50 lens techniques are known in the closer context of visualization, far more in related fields. In this paper, we extend our previous survey on interactive lenses for visualization. We propose a definition and a conceptual model of lenses as extensions of the classic visualization pipeline. An extensive review of the literature covers lens techniques for different types of data and different user tasks and also includes the technologies employed to display lenses and to interact with them. We introduce a taxonomy of lenses for visualization and illustrate its utility by dissecting in detail a multi‐touch lens for exploring large graph layouts. As a conclusion of our review, we identify challenges and unsolved problems to be addressed in future research.

We present YouTouch!, a system that tracks users in front of an interactive display wall and associates touches with users. With their large size, display walls are inherently suitable for multi-user interaction. However, current touch recognition technology does not distinguish between users, making it hard to provide personalized user interfaces or access to private data. In our system we place a commodity RGB + depth camera in front of the wall, allowing us to track users and correlate them with touch events. While the camera's driver is able to track people, it loses the user's ID whenever she is occluded or leaves the scene. In these cases, we re-identify the person by means of a descriptor comprised of color histograms of body parts and skeleton-based biometric measurements. Additional processing reliably handles short-term occlusion as well as assignment of touches to occluded users. YouTouch! requires no user instrumentation nor custom hardware, and there is no registration nor learning phase. Our system was thoroughly tested with data sets comprising 81 people, demonstrating its ability to re-identify users and correlate them to touches even under adverse conditions.

We propose to conduct a workshop on the topic of Immersive Analytics: a new multidisciplinary initiative to explore future interaction technologies for data analytics. Immersive Analytics aims to bring together researchers in Information Visualisation, Visual Analytics, Virtual and Augmented Reality and Natural User Interfaces. http://immersiveanalytics.net

By now, mobile 3D interaction is often limited to simple multi-touch input on standard devices and less expressive or hard to use. We present the concept of mobile dual-display devices that can be folded for the exploration of 3D content. We examine different display modes and introduce new presentation and 3D interaction techniques that make use of the special form factor and the added input modality of folding two displays. In particular, we also consider the advantages of our proposed device for head-coupled perspective rendering -- virtually extending the view and providing independent perspectives for two users.

In this work, we discuss important challenges arising when presenting business data in board meetings. After firstly considering the specific characteristic of board meetings, we have identified challenges concerning the following four topics emerging from the multi-display setup of (digital) boardrooms as well as the social situation in those board meetings: Control Presentations (Interaction), Content Presentation (Visualization), Discussion with Audience (Communication), and Remote Presence. Focusing on selected challenges, we propose first ideas how existing HCI research can help to tackle those challenges and thus help to improve efficiency of board meetings.

Interactive lenses have proven to be useful for many visualization applications where exploratory analysis is a primary task. Up to now, interaction with lenses is mostly limited to single-user, single-function lenses operated by mouse, keyboard and traditional parameter menus. To overcome these limitations, we propose MultiLens, touch-enabled magic lenses for fluently manipulating functions, parameters, and combinations of lenses on interactive surfaces. We contribute a novel multi-touch menu technique for magic lenses using a widget-based approach with a drag-snap slider for relative parameter adjustment. We also propose a continuous gesture set for rapidly changing lenses and their primary parameters in one seamless phrase. In addition, by supporting the combination of various lens functions, we create a generic multi-purpose lens tool. We illustrate our approach by investigating and implementing the concepts for the field of graph exploration. The prototype was evaluated in a user study with 22 participants comparing it to traditional parameter menus operated with both mouse and touch.

Scientific Visualization is generally based on very large and often high-dimensional data sets. In many cases (e.g., in the biomedical domain), high-resolution 3D data that changes over time and multiple data sets are involved. One important task in making sense of this data is finding interesting 2D views in the 3D space and additionally finding ways to handle changes over time. We explore how the combination of spatially aware mobiles and large displays can be used in this context. Specifically, we contribute both a precise selection technique for 2D cross sections and a concept for time-dependent 4D bookmarks that follow a point of interest over time. We implemented these techniques in a prototype application that visualizes biological Light Sheet Fluorescence Microscopy data and report on initial user feedback.

Research on interactive wall displays has thus far focused mostly on professional use. However, as large displays with support for touch and other input modalities become more common, it becomes reasonable to assume use in more casual settings as well. We present Miners, one of the first collaborative games for a touch-sensitive display wall, and investigate multimodal, multi-user interaction in this context. In this fast-paced game, four players cooperate to rescue workers trapped in an underground cave, with each player being able to influence the game world in a different way. In an exploratory study using Miners, we found that players enjoyed the game and showed very high engagement. On the other hand, awareness suffered: Players often missed events in other areas. In addition, we found limited awareness of other players' actions and social cues. We report on these results in detail and discuss implications for touch-based wall interaction in general as well as in other application contexts.

As Smart Manufacturing, Industrial Internet, Industrie 4.0, and Cyber-Physical Production System (CPPS) are becoming reality, the way process and manufacturing plants are operated has to change. Additionally, these developments - constituting the pervasive digitalisation of industry - have a profound effect on the way human workers and machines interact. This paper contrasts the current state of the art in plant control with a vision for the future. The scenario is illustrated by a realistic problem-solving process in a chemical plant. It describes an integrated industrial information and interaction space that leverages emerging technologies to enable plant operators to remain in control of future flexible modularised process plants. Our approach shows the advantages of an integrated information space which feeds interaction and collaboration using Virtual Reality (VR), novel display technologies and mobile devices.

For a desktop computer, we investigate how to enhance conventional mouse and keyboard interaction by combining the input modalities gaze and foot. This multimodal approach offers the potential for fluently performing both manual input (e.g., for precise object selection) and gaze-supported foot input (for pan and zoom) in zoomable information spaces in quick succession or even in parallel. For this, we take advantage of fast gaze input to implicitly indicate where to navigate to and additional explicit foot input for speed control while leaving the hands free for further manual input. This allows for taking advantage of gaze input in a subtle and unobtrusive way. We have carefully elaborated and investigated three variants of foot controls incorporating one-, two- and multidirectional foot pedals in combination with gaze. These were evaluated and compared to mouse-only input in a user study using Google Earth as a geographic information system. The results suggest that gaze-supported foot input is feasible for convenient, user-friendly navigation and comparable to mouse input and encourage further investigations of gaze-supported foot controls.

We explore the high potential of elastic controllers for casual interaction in mobile and ubiquitous computing scenarios. While several remote interaction techniques with handheld or body-worn devices have been proposed, the usage of string-based, elastic interaction is still underexplored. Therefore, we first introduce a systematic design space along the axes reference system, interaction dimensions, sensing methods and haptic feedback. Our main contribution is Elasticcon, a versatile, wearable device with a retractable string and a set of exchangeable traction knobs. This elastic controller provides several degrees of freedom and allows rich interaction techniques. As a result of an iterative design process, we also contribute two working prototypes for belt-worn and handheld use. To demonstrate their versatility, we implemented several promising application scenarios. We tested Elasticcon in three smaller user studies investigating qualitative usability aspects and found initial evidence for elastic controllers as being comfortable, casual and yet accurate interaction devices.

At present, photorealistic augmentation is not yet possible since the computational power of mobile devices is insufficient. Even streaming solutions from stationary PCs cause a latency that affects user interactions considerably. Therefore, we introduce a differential rendering method that allows for a consistent illumination of the inserted virtual objects on mobile devices, avoiding delays. The computation effort is shared between a stationary PC and the mobile devices to make use of the capacities available on both sides. The method is designed such that only a minimum amount of data has to be transferred asynchronously between the participants. This allows for an interactive illumination of virtual objects with a consistent appearance under both temporally and spatially varying real illumination conditions. To describe the complex near-field illumination in an indoor scenario, HDR video cameras are used to capture the illumination from multiple directions. In this way, sources of illumination can be considered that are not directly visible to the mobile device because of occlusions and the limited field of view. While our method focuses on Lambertian materials, we also provide some initial approaches to approximate non-diffuse virtual objects and thereby allow for a wider field of application at nearly the same cost.

As a novel class of mobile devices with rich interaction capabilities we introduce tPads -- transparent display tablets. tPads are the result of a systematic design investigation into the ways and benefits of interacting with transparent mobiles which goes beyond traditional mobile interactions and augmented reality (AR) applications. Through a user-centered design process we explored interaction techniques for transparent-display mobiles and classified them into four categories: overlay, dual display & input, surface capture and model-based interactions. We investigated the technical feasibility of such interactions by designing and building two touch-enabled semi-transparent tablets called tPads and a range of tPad applications. Further, a user study shows that tPad interactions applied to everyday mobile tasks (application switching and image capture) outperform current mobile interactions and were preferred by users. Our hands-on design process and experimental evaluation demonstrate that transparent displays provide valuable interaction opportunities for mobile devices.

In many cases, Tangible User Interfaces allow the manipulation of digital content with physical objects recognized by an interactive tabletop. Usually, such tangible objects are made of opaque wood or synthetic materials, thereby occluding the display. In this paper, we systematically investigate the promising potential of tangibles entirely made of transparent or translucent materials. Besides visualizing content directly below a manipulable tangible, transparent objects also facilitate direct touch interaction with the content below, dynamic illumination and glowing effects. We propose a comprehensive design space for transparent tangibles on tabletops based on a thorough review of existing work. By reporting on our own experiments and prototypes, we address several gaps in this design space, regarding aspects of both interaction and visualization. These include the illumination of tangibles as well as the precise input with transparent tangibles for which we also present the promising results of an initial user study. Finally, benefits and shortcomings of transparent tangibles are discussed and resulting design considerations are presented.

The multi-touch-based pinch to zoom, drag and flick to pan metaphor has gained wide popularity on mobile displays, where it is the paradigm of choice for navigating 2D documents. But is finger-based navigation really the gold standard' In this paper, we present a comprehensive user study with 40 participants, in which we systematically compared the Pinch-Drag-Flick approach with a technique that relies on spatial manipulation, such as lifting a display up/down to zoom. While we solely considered known techniques, we put considerable effort in implementing both input strategies on popular consumer hardware (iPhone, iPad). Our results show that spatial manipulation can significantly outperform traditional Pinch-Drag-Flick. Given the carefully optimized prototypes, we are confident to have found strong arguments that future generations of mobile devices could rely much more on spatial interaction principles.

This demonstration on the Nao robot uses the selection of behavior based on a feedback type and an expressivity value to generate and execute appropriate feedback. It aims to ease the authoring process by using variable gestures.

This work aims at establishing a more variable, and thus attractive, communication with humanoids. For this purpose we developed a method of dynamically expressing emotions and intentions associated with parametrised gestures. First, gestures and possible parameters, which are necessary for the generation of a whole-body gesture set, were analyzed. A gesture's inner and outer expressivity is thereby defined which leads to the differentiation of single gestures and variable gestural expressions. Gestures are subsequently classified into (feedback) categories and related depending on their expressivity. We developed a gesture set consisting of six categories including over 50 variable gestures. As proof of concept, the gesture set has been implemented to allow for an easy and flexible authoring process of gesture-supported communication.

Mobile devices become more and more important today, especially for augmented reality (AR) applications in which the camera of the mobile device acts like a window into the mixed reality world. Up to now, no photorealistic augmentation is possible since the computational power of the mobile devices is still too weak. Even a streaming solution from a stationary PC would cause a latency that affects user interactions considerably. Therefore, we introduce a differential illumination method that allows for a consistent illumination of the inserted virtual objects on mobile devices, avoiding a delay. The necessary computation effort is shared between a stationary PC and the mobile devices to make use of the capacities available on both sides. The method is designed such that only a minimum amount of data has to be transferred asynchronously between the stationary PC and one or multiple mobile devices. This allows for an interactive illumination of virtual objects with a consistent appearance under both temporally and spatially varying real illumination conditions. To describe the complex near-field illumination in an indoor scenario, multiple HDR video cameras are used to capture the illumination from multiple directions. In this way, sources of illumination can be considered that are not directly visible to the mobile device because of occlusions and the limited field of view of built-in cameras.

Players of digital games are limited by the constraints of the game's implementation. Players cannot fly a kite, plant a tree or make friends with a dragon if these activities were not coded within the game. Game orchestration relaxes these restrictions by allowing players to create game narratives and settings as the game is being played. This enables players to express their creativity beyond the strictures of the game's implementation. We present Tabula Rasa, a novel game orchestration tool based on an efficient tabletop interface. Based on a study of 20 game orchestration sessions using Tabula Rasa, we identify five behavioural patterns adopted by orchestrators, and four styles of collaborative interaction between orchestrators and players. Finally, we present recommendations for designers of game orchestration systems.

We investigate how to seamlessly bridge the gap between users and distant displays for basic interaction tasks, such as object selection and manipulation. For this, we take advantage of very fast and implicit, yet imprecise gaze- and head-directed input in combination with ubiquitous smartphones for additional manual touch control. We have carefully elaborated two novel and consistent sets of gaze-supported interaction techniques based on touch-enhanced gaze pointers and local magnification lenses. These conflict-free sets allow for fluently selecting and positioning distant targets. Both sets were evaluated in a user study with 16 participants. Overall, users were fastest with a touch-enhanced gaze pointer for selecting and positioning an object after some training. While the positive user feedback for both sets suggests that our proposed gaze- and head-directed interaction techniques are suitable for a convenient and fluent selection and manipulation of distant targets, further improvements are necessary for more precise cursor control.

A large body of work asserts that interactive tabletops are well suited for group work, and numerous studies have examined these devices in educational contexts. However, few of the described systems support simulations for collaborative learning, and none of them explicitly address immersion. We present SimMed, a system allowing medical students to collaboratively diagnose and treat a virtual patient using an interactive tabletop. The hybrid user interface combines elements of virtual reality with multitouch input. The paper delineates the development process of the system and rationale behind a range of interface design decisions. Thereby, the role of realism in gaining procedural knowledge is discussed - in particular, the interplay between realism, immersion and training goals. We implemented several medical test cases and evaluated our approach with a user study that suggests the great potential of the system. Results show a high level of immersion, cooperation and engagement by the students.

Interactive spaces are ubiquitous computing environments for computer-supported collaboration that exploit and enhance the existing cognitive, physical and social skills of users or groups of users. The workshop aims at documenting and advancing the current state-of-the-art of co-located collaboration in interactive spaces and identifying research challenges and formulating a research agenda by inviting high-quality position and research papers from HCI, Information Visualization, CSCW and CSCL.

We introduce Stackables: tangibles designed to support faceted information seeking in a variety of contexts. We are faced, more than ever, with tasks that require us to find, access, and act on information by ourselves or together with others. Current interfaces for browsing and search in large data spaces, however, largely focus on the support of either individual or collaborative activities. Stackables were designed to bridge this gap and be useful in meetings, for sharing results from individual search activities, and for realistic datasets including multiple facets with large value ranges. Each Stackable tangible represents search parameters that can be shared amongst collaborators, modified during an information seeking process, and stored and transferred. We describe Stackables, their flexible and expressive combination to formulate queries, and the underlying interaction concept in detail. An evaluation provides initial evidence of their usability in targeted and exploratory information seeking tasks.

Lightweight spatially aware displays (Tangible Magic Lenses) are an effective approach for exploring complex information spaces within a tabletop environment. One way of using the 3D space above a horizontal surface is to divide it into discrete parallel layers stacked upon each other. Horizontal and vertical lens movements are essential tasks for the style of multi-layer interaction associated with it. We conducted a comprehensive user study with 18 participants investigating fundamental issues such as optimal number of layers and their thickness, movement and holding accuracies, and physical boundaries of the interaction volume. Findings include a rather limited overall interaction height (44 cm), a different minimal layer thickness for vertical and horizontal search tasks (1 cm/4 cm), a reasonable maximum number of layers depending on the primary task, and a convenience zone in the middle for horizontal search. Derived from that, design guidelines are also presented.

While eye tracking has a high potential for fast selection tasks, it is often regarded as error-prone and unnatural, especially for gaze-only interaction. To improve on that, we propose gaze-supported interaction as a more natural and effective way combining a user's gaze with touch input from a handheld device. In particular, we contribute a set of novel and practical gaze-supported selection techniques for distant displays. Designed according to the principle gaze suggests, touch confirms they include an enhanced gaze-directed cursor, local zoom lenses and more elaborated techniques utilizing manual fine positioning of the cursor via touch. In a comprehensive user study with 24 participants, we investigated the potential of these techniques for different target sizes and distances. All novel techniques outperformed a simple gaze-directed cursor and showed individual advantages. In particular those techniques using touch for fine cursor adjustments (MAGIC touch) and for cycling through a list of possible close-to-gaze targets (MAGIC tab) demonstrated a high overall performance and usability.

Since eye gaze may serve as an efficient and natural input for steering in virtual 3D scenes, we investigate the design of eye gaze steering user interfaces (UIs) in this paper. We discuss design considerations and propose design alternatives based on two selected steering approaches differing in input condition (discrete vs. continuous) and velocity selection (constant vs. gradient-based). The proposed UIs have been iteratively advanced based on two user studies with twelve participants each. In particular, the combination of continuous and gradient-based input shows a high potential, because it allows for gradually changing the moving speed and direction depending on a user's point-of-regard. This has the advantage of reducing overshooting problems and dwell-time activations. We also investigate discrete constant input for which virtual buttons are toggled using gaze dwelling. As an alternative, we propose the Sticky Gaze Pointer as a more flexible way of discrete input.

Remote pan-and-zoom control for the exploration of large information spaces is of interest for various application areas, such as browsing through medical data in sterile environments or investigating geographic information systems on a distant display. In this context, considering a user's visual attention for pan-and-zoom operations could be of interest. In this paper, we investigate the potential of gaze-supported panning in combination with different zooming modalities: (1) a mouse scroll wheel, (2) tilting a handheld device, and (3) touch gestures on a smartphone. Thereby, it is possible to zoom in at a location a user currently looks at (i.e., gaze-directed pivot zoom). These techniques have been tested with Google Earth by ten participants in a user study. While participants were fastest with the already familiar mouse-only base condition, the user feedback indicates a particularly high potential of the gaze-supported pivot zooming in combination with a scroll wheel or touch gesture.

Precise alignment of graphical objects and the creation of accurate layouts are crucial activities in many applications, such as graphics design tools, presentation software or graph editors. Surface computing is very promising for these application domains but not fully explored yet. In this paper we contribute two tools which support layout tasks on interactive displays: interactive grids and multi-touch alignment guides. Both tools allow the precise positioning of graphical objects in a flexible and fluent way by multi-touch input. Direct bimanual interaction and physical metaphors are applied to arrange objects along straight lines and curves. A formative user evaluation showed promising results with regard to a productive and easy use of the tools.

Background: Software product line engineering provides an effective mechanism to implement variable software.However, the usage of preprocessors, which is typical in industry, is heavily criticized, because it often leads to obfuscated code.Using background colors to support comprehensibility has shown effective, however, scalability to large software product lines (SPLs) is questionable.Aim: Our goal is to implement and evaluate scalable usage of background colors for industrial-sized SPLs.Method: We designed and implemented scalable concepts in a tool called FeatureCommander.To evaluate its effectiveness, we conducted a controlled experiment with a large real-world SPL with over 160,000 lines of code and 340 features.We used a within-subjects design with treatments colors and no colors.We compared correctness and response time of tasks for both treatments.Results: For certain kinds of tasks, background colors improve program comprehension.Furthermore, subjects generally favor background colors.Conclusion: We show that background colors can improve program comprehension in large SPLs.Based on these encouraging results, we will continue our work improving program comprehension in large SPLs.Difficulty U value 20.5 24.5 17.5 18 10.

Software product line engineering provides efficient means to develop variable software. To support program comprehension of software product lines (SPLs), we developed View Infinity, a tool that provides seamless and semantic zooming of different abstraction layers of an SPL. First results of a qualitative study with experienced SPL developers are promising and indicate that View Infinity is useful and intuitive to use.

Gaze visualizations hold the potential to facilitate usability studies of interactive systems. However, visual gaze analysis in three-dimensional virtual environments still lacks methods and techniques for aggregating attentional representations. We propose three novel gaze visualizations for the application in such environments: projected, object-based, and surface-based attentional maps. These techniques provide an overview of how visual attention is distributed across a scene, among different models, and across a model's surface. Two user studies conducted among eye tracking and visualization experts approve the high value of these techniques for the fast evaluation of eye tracking studies in virtual environments.

Gaze visualizations represent an effective way for gaining fast insights into eye tracking data. Current approaches do not adequately support eye tracking studies for three-dimensional (3D) virtual environments. Hence, we propose a set of advanced gaze visualization techniques for supporting gaze behavior analysis in such environments. Similar to commonly used gaze visualizations for two-dimensional stimuli (e.g., images and websites), we contribute advanced 3D scan paths and 3D attentional maps. In addition, we introduce a models of interest timeline depicting viewed models, which can be used for displaying scan paths in a selected time segment. A prototype toolkit is also discussed which combines an implementation of our proposed techniques. Their potential for facilitating eye tracking studies in virtual environments was supported by a user study among eye tracking and visualization experts.

The C preprocessor is often used in practice to implement variability in software product lines. Using #ifdef statements provokes problems such as obfuscated source code, yet they will still be used in practice at least in the medium-term future. With CIDE, we demonstrate a tool to improve understanding and maintaining code that contains #ifdef statements by visualizing them with colors and providing different views on the code.

Faceted browsing is a promising way to incrementally refine data sets. Current approaches do not scale well in terms of screen size and have shortcomings in interacting with hierarchical facets. This paper introduces FacetZoom, a novel multi-scale widget combining facet browsing with zoomable user interfaces. Hierarchical facets are displayed as space-filling widgets which allow a fast traversal across all levels while simultaneously maintaining context. We contribute both a seamless continuous navigation and a quick tap-and-center interaction. Two prototypes are described which successfully apply the space-structuring widget to continuous, sampled data and an information collection. A formative user study of the latter indicates that the interface scales well to small screens. FacetZoom is versatile and offers consistent searching and browsing behaviors in a multitude of applications and device settings.

Current mobile music players and managers rely on scrolling long and hierarchically structured lists of items. They do not scale well to various screen sizes. As a solution, this paper introduces Mambo for browsing personal music collections on mobile and other devices. Songs, albums, or artists can be browsed and filtered according to different hierarchical metadata facets such as time, genre, or alphabet. The FacetZoom widget constitutes the basic metaphor and combines visual faceted browsing with zoomable user interfaces. To search, browse, and filter data in a consistent way, we contribute both a continuous multi-scale and a discrete tap-and-center navigation which is especially suited for mobile devices. A 24-subject formative user study was conducted, investigating the first prototype under PDA and Ultra Mobile PC display conditions using two design variants. The results indicate that the facet-based zooming approach scales well to various display sizes.

This is a short presentation of a uniform approach for specifying mixed reality user interfaces, including 3D interaction techniques and 3D widgets. Our main goal is to facilitate the process of reusing previous work, so more complex applications can be built and documented in a formal and uniform way. We describe here the conceptual model of user interface components, which allows us to generalize user interface components and to port them to different hardware settings and application contexts. An XML-based specification language implements the conceptual model and allows for automatic processing and tool support.