environment

Many context-aware services make the assumption that the context they use is completely accurate. However, in reality, both sensed and interpreted context is often ambiguous. A challenge facing the development of realistic and deployable context-aware services, therefore, is the ability to handle ambiguous context. In this paper, we describe an architecture that supports the building of context-aware services that assume context is ambiguous and allows for mediation of ambiguity by mobile users in aware environments. We illustrate the use of our architecture and evaluate it through three example context-aware services, a word predictor system, an In/Out Board, and a reminder tool.

This paper explores interfaces to virtual environments supporting multiple users. An interface to an environment allowing interaction with virtual artefacts is constructed, drawing on previous proposals for 'desktop' virtual environments. These include the use of Peripheral Lenses to support peripheral awareness in collaboration; and extending the ways in which users' actions are represented for each other. Through a qualitative analysis of a design task, the effect of the proposals is outlined. Observations indicate that, whilst these designs go some way to re-constructing physical co-presence in terms of awareness and interaction through the environment, some issues remain. Notably, peripheral distortion in supporting awareness may cause problematic interactions with and through the virtual world; and extended representations of actions may still allow problems in re-assembling the composition of others' actions. We discuss the potential for: designing representations for distorted peripheral perception; and explicitly displaying the course of action in object-focused interaction.

In this paper, we describe The Designer's Augmented Reality Toolkit (DART). DART is built on top of Macromedia Director, a widely used multimedia development environment. We summarize the most significant problems faced by designers working with AR in the real world, and discuss how DART addresses them. Most of DART is implemented in an interpreted scripting language, and can be modified by designers to suit their needs. Our work focuses on supporting early design activities, especially a rapid transition from story-boards to working experience, so that the experiential part of a design can be tested early and often. DART allows designers to specify complex relationships between the physical and virtual worlds, and supports 3D animatic actors (informal, sketch-based content) in addition to more polished content. Designers can capture and replay synchronized video and sensor data, allowing them to work off-site and to test specific parts of their experience more effectively.

This paper describes the concept of Time-Machine Computing (TMC), a time-centric approach to organizing information on computers. A system based on Time-Machine Computing allows a user to visit the past and the future states of computers. When a user needs to refer to a document that he/she was working on at some other time, he/she can travel in the time dimension and the system restores the computer state at that time. Since the user's activities on the system are automatically archived, the user's daily workspace is seamlessly integrated into the information archive. The combination of spatial information management of the desktop metaphor and time traveling allows a user to organize and archive information without being bothered by folder hierarchies or the file classification problems that are common in today's desktop environments. TMC also provides a mechanism for linking multiple applications and external information sources by exchanging time information. This paper describes the key features of TMC, a time-machine desktop environment called “TimeScape,” and several time-oriented application integration examples.

We describe a view-management component for interactive 3D user interfaces. By view management, we mean maintaining visual constraints on the projections of objects on the view plane, such as locating related objects near each other, or preventing objects from occluding each other. Our view-management component accomplishes this by modifying selected object properties, including position, size, and transparency, which are tagged to indicate their constraints. For example, some objects may have geometric properties that are determined entirely by a physical simulation and which cannot be modified, while other objects may be annotations whose position and size are flexible.We introduce algorithms that use upright rectangular extents to represent on the view plane a dynamic and efficient approximation of the occupied space containing the projections of visible portions of 3D objects, as well as the unoccupied space in which objects can be placed to avoid occlusion. Layout decisions from previous frames are taken into account to reduce visual discontinuities. We present augmented reality and virtual reality examples to which we have applied our approach, including a dynamically labeled and annotated environment.

We describe the design of and experience with PointRight, a peer-to-peer pointer and keyboard redirection system that operates in multi-machine, multi-user environments. PointRight employs a geometric model for redirecting input across screens driven by multiple independent machines and operating systems. It was created for interactive workspaces that include large, shared displays and individual laptops, but is a general tool that supports many different configurations and modes of use. Although previous systems have provided for re-routing pointer and keyboard control, in this paper we present a more general and flexible system, along with an analysis of the types of re-binding that must be handled by any pointer redirection system This paper describes the system, the ways in which it has been used, and the lessons that have been learned from its use over the last two years.

Multi-display environments compose displays that can be at different locations from and different angles to the user; as a result, it can become very difficult to manage windows, read text, and manipulate objects. We investigate the idea of perspective as a way to solve these problems in multi-display environments. We first identify basic display and control factors that are affected by perspective, such as visibility, fracture, and sharing. We then present the design and implementation of E-conic, a multi-display multi-user environment that uses location data about displays and users to dynamically correct perspective. We carried out a controlled experiment to test the benefits of perspective correction in basic interaction tasks like targeting, steering, aligning, pattern-matching and reading. Our results show that perspective correction significantly and substantially improves user performance in all these tasks.

The first requirement of a "spatial mouse" is the ability to identify the object that it is aiming at. Among many possible technologies that can be employed for this purpose, possibly the best solution would be object recognition by machine vision. The problem, however, is that object recognition algorithms are not yet reliable enough or light enough for hand-held devices. This paper demonstrates that a simple object recognition algorithm can become a practical solution when augmented by interactivity. The user draw a circle around a target using a spatial mouse, and the mouse captures a series of camera frames. The frames can be easily stitched together to give a target image separated from the background, with which we need only additional steps of feature extraction and object classification. We present here results from two experiments with a few household objects.

This paper describes a testbed and method for characterizing the dynamic response of the type of spatial displacement transducers commonly used in virtual environment (VE) applications. The testbed consists of a motorized rotary swing arm that imparts known displacement inputs to the VE sensor. The experimental method involves a series of tests in which the sensor is displaced back and forth at a number of controlled frequencies that span the bandwidth of volitional human movement. During the tests, actual swing arm angle and reported VE sensor displacements are collected and time stamped. Because of the time stamping technique, the response time of the sensor can be measured directly, independent of latencies in data transmission from the sensor unit and any processing by the interface applications running on the host computer. Analysis of these experimental results allows sensor time delay and gain characteristics to be determined as a function of input frequency. Results from tests of several differnt VE spatial sensors (Ascension, Logitech, and Polhemus) are presented here to demonstrate use of the testbed and method.

We describe a view-management component for interactive 3D user interfaces. By view management, we mean maintaining visual constraints on the projections of objects on the view plane, such as locating related objects near each other, or preventing objects from occluding each other. Our view-management component accomplishes this by modifying selected object properties, including position, size, and transparency, which are tagged to indicate their constraints. For example, some objects may have geometric properties that are determined entirely by a physical simulation and which cannot be modified, while other objects may be annotations whose position and size are flexible.We introduce algorithms that use upright rectangular extents to represent on the view plane a dynamic and efficient approximation of the occupied space containing the projections of visible portions of 3D objects, as well as the unoccupied space in which objects can be placed to avoid occlusion. Layout decisions from previous frames are taken into account to reduce visual discontinuities. We present augmented reality and virtual reality examples to which we have applied our approach, including a dynamically labeled and annotated environment.

We are developing an interaction technique for rich nonverbal communication through an avatar. By writing a single letter on a pen tablet device, a user can express their ideas or intentions, non-verbally, using their avatar body. Our system solves the difficult problem of controlling the movements of a highly articulated, 3D avatar model using a common input device within the context of an office environment. We believe that writing is a richly expressive and natural means for controlling expressive avatar gesture.