Projects

PolarTrack is a novel camera-based approach to detecting and tracking mobile devices inside the capture volume. In PolarTrack, a polarization filter continuously rotates in front of an off-the-shelf color camera, which causes the displays of observed devices to periodically blink in the camera feed. The periodic blinking results from the physical characteristics of current displays, which shine polarized light either through an LC overlay to produce images or through a polarizer to reduce light reflections on OLED displays. PolarTrack runs a simple detection algorithm on the camera feed to segment displays and track their locations and orientations, which makes PolarTrack particularly suitable as a tracking system for cross-device interaction with mobile devices. Our evaluation of PolarTrack's tracking quality and comparison with state-of-the-art camera-based multi-device tracking showed a better tracking accuracy and precision with similar tracking reliability. PolarTrack works as standalone multi-device tracking but is also compatible with existing camera-based tracking systems and can complement them to compensate for their limitations.

A sizable part of HCI research on cross-device interaction is driven by the vision of users conducting complex knowledge work seamlessly across multiple mobile devices. This is based on the Weiserian assumption that people will be inclined to distribute their work across multiple ``pads' if such are available. We observed that this is not the reality today, even when devices were in abundance. We present a study with 24 participants in 12 dyads completing a collaborative visualization task with up to six tablets. They could choose between three different visualization types to answer questions about economic data. Tasks were designed to afford simultaneous use of tablets, either with linked or independent views. We found that users typically utilized only one tablet per user. A quantitative and qualitative analysis revealed a ``legacy bias' that introduced barriers for using more tablets and reduced the overall benefit of multi-device visualization.

In this workshop, we will review and discuss open issues, technical challenges and conceptual models for multi-device spatial or proxemic interaction. We aim to bring together researchers, students and practitioners working on technical infrastructures, studies and designs of spatial in-terfaces, or domain specific multi-device applications that use space as a unit of analysis. We focus specifically on analysing how such interfaces, tools and tracking technolo-gy can be deployed "in the wild". The workshop will facili-tate knowledge exchange about the current state of spatial and proxemic interactive systems, identify application do-mains and enabling technologies for cross-surface interac-tions in the wild, and establish a research community to develop effective strategies for successful design of cross-device interactions.

Cross-device interaction is rarely observed in everyday life and outside of research facilities. In this position paper we explore potential reasons for this shortcoming and discuss why the web is a promising enabling technology for crossdevice interactions. We propose a concept for new, crossdevice centric web standards that would allow to develop, deploy, and use cross-device applications in everyday life.

Cross-device interaction between multiple mobile devices is a popular field of research in HCI. However, the appropriate design of this interaction is still an open question, with competing approaches such as spatially-aware vs. spatially-agnostic techniques. In this paper, we present the results of a two-phase user study that explores this design space: In phase 1, we elicited gestures for typical mobile cross-device tasks from 4 focus groups (N=17). The results show that 71% of the elicited gestures were spatially-aware and that participants strongly associated cross-device tasks with interacting and thinking in space. In phase 2, we implemented one spatially-agnostic and two spatially-aware techniques from phase 1 and compared them in a controlled experiment (N=12). The results indicate that spatially-aware techniques are preferred by users and can decrease mental demand, effort, and frustration, but only when they are designed with great care. We conclude with a summary of findings to inform the design of future cross-device interactions.

While Mark Weiser's vision of ubiquitous computing is getting closer to reality, a fundamental part of it - the interconnection of devices into a "ubiquitous network" - is not achieved yet. Differences in hardware, architecture, and missing standardizations are just some reasons for this. We think that existing research is not versatile enough and too tailored to either single applications, hardware, or location. We contribute Connichiwa -- a versatile framework for creating web applications across multiple devices. We base Connichiwa on four key goals: integration of existing devices, independence of network infrastructure, versatility of application scenario, and usability of its API. Connichiwa runs web applications on off-the-shelf consumer devices. With no external dependencies, such as a server, it enables a great variety of possible scenarios. We tested the technical feasibility of Connichiwa in seven example applications and plan to evaluate the framework and the usability of its API in a one-week Hackathon.

We present HuddleLamp, a desk lamp with an integrated RGB-D camera that precisely tracks the movements and positions of mobile displays and hands on a table. This enables a new breed of spatially-aware multi-user and multi-device applications for around-the-table collaboration without an interactive tabletop. At any time users can add or remove displays and reconfigure them in space in an ad-hoc manner without the need of installing any software or attaching markers. Additionally, hands are tracked to detect interactions above and between displays, enabling fluent cross-device interactions. The demo consists of the technical implementation of HuddleLamp's hybrid sensing and a Web-based architecture for installation-free ad-hoc collaboration. We demonstrate our implementation by showing a variety of possible interaction techniques.

We present HuddleLamp, a desk lamp with an integrated RGB-D camera that precisely tracks the movements and positions of mobile displays and hands on a table. This enables a new breed of spatially-aware multi-user and multi-device applications for around-the-table collaboration without an interactive tabletop. At any time users can add or remove displays and reconfigure them in space in an ad-hoc manner without the need of installing any software or attaching markers. Additionally, hands are tracked to detect interactions above and between displays, enabling fluent cross-device interactions. The demo consists of the technical implementation of HuddleLamp's hybrid sensing and a Web-based architecture for installation-free ad-hoc collaboration. We demonstrate our implementation by showing a variety of possible interaction techniques.

Although Web search is typically regarded as a solitary activity, collaborative search approaches are becoming an increasingly relevant topic for HCI and distributed user interfaces (DUIs). Today’s collaborative search systems lack comprehensive search support that also involves pre- or post-search activities such as preparation or sensemaking. We believe that post-WIMP DUIs can help to better support social search and have identified four design goals that are critical for their successful design. In consequence, we present TwisterSearch, an interactive DUI prototype that meets our four design goals.

This demo presents TwisterSearch, a system for co-located and collaborative Web search that was designed in accordance with the canonical model of social search by Evans and Chi (2009). In a first phase before search, participants frame the context of the intended search and thereafter gather initial information requirements on a tabletop. These requirements are then refined through discussion and yield the foundation for the search task itself, which is performed in parallel on multiple mobile displays. These private devices are used to search the Web for evidence files and to populate the visual workspace of the tabletop with them. Moreover, the personal device allows both a highly parallel search as well as a tightly-coupled collaborative search, to enable seamless switching between collective and solitary search activities. In our TwisterSearch demo, participants can have a firsthand experience of these different individual phases of social search.