Christian Kray

Presenting route instructions on mobile devices

In this paper, we evaluate several means of presenting route instructions to a mobile user. Starting from an abstract language-independent description of a route segment, we show how to generate various presentations for a mobile device ranging from spoken instructions to 3D visualizations. We then examine the relationship between the quality of positional information, available resources and the different types of presentations. The paper concludes with guidelines that help to determine which presentation to choose for a given situation

A relative positioning system for co-located mobile devices

If a mobile computing device knows how it is positioned and oriented in relation to other devices nearby, then it can provide enhanced support for multi-device and multi-user interactions. Existing systems that provide position information to mobile computers are reliant on externally deployed infrastructure, such as beacons or sensors in the environment. We introduce the Relate system, which provides fine-grained relative position information to co-located devices on the basis of peer-to-peer sensing, thus overcoming dependence on any external infrastructure. The system is realised as a hardware/software plug-in, using ultrasound for peer-to-peer sensing, USB to interface with standard mobile devices, and data abstraction and inferencing to map sensor data to a spatial model that maintains both quantitative and qualitative relationships. We present a set of services and applications to demonstrate the utility of the system. We report experimental results on the accuracy of the relative position and orientation estimates, and other aspects of system performance.

Cooperative Artefacts: Assessing Real World Situations with Embedded Technology

Ubiquitous computing is giving rise to applications that interact very closely with activity in the real world, usually involving instrumentation of environments. In contrast, we propose Cooperative Artefacts that are able to cooperatively assess their situation in the world, without need for supporting infrastructure in the environment. The Cooperative Artefact concept is based on embedded domain knowledge, perceptual intelligence, and rule-based inference in movable artefacts. We demonstrate the concept with design and implementation of augmented chemical containers that are able to detect and alert potentially hazardous situations concerning their storage.

A Survey of Map-based Mobile Guides

In this chapter, we present an overview of mobile guides that rely on maps or map-like representations in providing their services. We discuss technical issues as well as problems related to human factors that mobile guides have to cope with in order to assist their respective users. The main part of the chapters describes a number of relevant systems in the field of mobile guides, ranging from influential work such as Cyberguide to systems that offer unique services such as TellMaris. The comparison is based on the issues we identified initially. We conclude with an outlook on future directions such as collaborative usage, new means of interaction and further personalisation of mobile services.

Exploring bluetooth based mobile phone interaction with the hermes photo display

One of the most promising possibilities for supporting user interaction with public displays is the use of personal mobile phones. Furthermore, by utilising Bluetooth users should have the capability to interact with displays without incurring personal financial connectivity costs. However, despite the relative maturity of Bluetooth as a standard and its widespread adoption in todays mobile phones, little exploration seems to have taken place in this area - despite its apparent significant potential. This paper describe the findings of an exploratory study involving our Hermes Photo Display which has been extended to enable users with a suitable phone to both send and receive pictures over Bluetooth. We present both the technical challenges of working with Bluetooth and, through our user study, we present initial insights into general user acceptability issues and the potential for such a display to facilitate notions of community.

User-defined gestures for connecting mobile phones, public displays, and tabletops

Gestures can offer an intuitive way to interact with a computer. In this paper, we investigate the question whether gesturing with a mobile phone can help to perform complex tasks involving two devices. We present results from a user study, where we asked participants to spontaneously produce gestures with their phone to trigger a set of different activities. We investigated three conditions (device configurations): phone-to-phone, phone-to-tabletop, and phone to public display. We report on the kinds of gestures we observed as well as on feedback from the participants, and provide an initial assessment of which sensors might facilitate gesture recognition in a phone. The results suggest that phone gestures have the potential to be easily understood by end users and that certain device configurations and activities may be well suited for gesture control.

Sensing and visualizing spatial relations of mobile devices

Location information can be used to enhance interaction with mobile devices. While many location systems require instrumentation of the environment, we present a system that allows devices to measure their spatial relations in a true peer-to-peer fashion. The system is based on custom sensor hardware implemented as USB dongle, and computes spatial relations in real-time. In extension of this system we propose a set of spatialized widgets for incorporation of spatial relations in the user interface. The use of these widgets is illustrated in a number of applications, showing how spatial relations can be employed to support and streamline interaction with mobile devices.

Adaptive navigation support with public displays

In this paper, we describe a public navigation system which uses adaptive displays as directional signs. The displays are mounted to walls where they provide passersbys with directional information. Each sign is an autonomous, wirelessly networked digital displays connected to a central server. The signs are position-aware and able to adapt their display content in accordance with their current position. Advantages of such a navigation system include improved flexibility, dynamic adaptation and ease of setup and maintenance.

Supporting device discovery and spontaneous interaction with spatial references

The RELATE interaction model is designed to support spontaneous interaction of mobile users with devices and services in their environment. The model is based on spatial references that capture the spatial relationship of a user’s device with other co-located devices. Spatial references are obtained by relative position sensing and integrated in the mobile user interface to spatially visualize the arrangement of discovered devices, and to provide direct access for interaction across devices. In this paper we discuss two prototype systems demonstrating the utility of the model in collaborative and mobile settings, and present a study on usability of spatial list and map representations for device selection.

Exploring factors that influence the combined use of mobile devices and public displays for pedestrian navigation

Large displays are rapidly proliferating in public spaces, and could therefore be an attractive resource to support nomadic users in such contexts, e. g. by providing additional screen real estate or by augmenting services delivered through a mobile device. While previous work on combining public displays and mobile devices has identified a number of benefits of this combination, it is not yet clear if users will actually use such a system and if they do, why and when. In this paper, we present two initial user studies investigating factors relevant to user acceptance and usability in the context of a deployed system that provides pedestrian navigation support through a combination of mobile devices and public displays. Based on the results from a repertory grid analysis, we identify dimensions that are relevant for users deciding whether to use a public display or not, and discuss implications for the design of such systems.