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Computer users working with large visual documents, such as large layouts, blueprints, or maps perform tasks that require them to simultaneously access overview information while working on details. To avoid the need for zooming, users currently have to choose between using a sufficiently large screen or applying appropriate visualization techniques. Currently available hi-res "wall-size" screens, however, are cost-intensive, space-intensive, or both. Visualization techniques allow the user to more efficiently use the given screen space, but in exchange they either require the user to switch between multiple views or they introduce distortion.In this paper, we present a novel approach to simultaneously display focus and context information. Focus plus context screens consist of a hi-res display and a larger low-res display. Image content is displayed such that the scaling of the display content is preserved, while its resolution may vary according to which display region it is displayed in. Focus plus context screens are applicable to practically all tasks that currently use overviews or fisheye views, but unlike these visualization techniques, focus plus context screens provide a single, non-distorted view. We present a prototype that seamlessly integrates an LCD with a projection screen and demonstrate four applications that we have adapted so far.

Classroom BRIDGE supports activity awareness by facilitating planning and goal revision in collaborative, project-based middle school science. It integrates large-screen and desktop views of project times to support incidental creation of awareness information through routine document transactions, integrated presentation of awareness information as part of workspace views, and public access to subgroup activity. It demonstrates and develops an object replication approach to integrating synchronous and asynchronous distributed work for a platform incorporating both desktop and large-screen devices. This paper describes an implementation of these concepts with preliminary evaluation data, using timeline-based user interfaces.

Most current implementations of multi-touch screens are still too expensive or too bulky for widespread adoption. To improve this situation, this work describes the electronics and software needed to collect more data than one pair of coordinates from a standard 4-wire touch screen. With this system, one can measure the pressure of a single touch and approximately sense the coordinates of two touches occurring simultaneously. Naturally, the system cannot offer the accuracy and versatility of full multi-touch screens. Nonetheless, several example applications ranging from painting to zooming demonstrate a broad spectrum of use.

ScreenCrayons is a system for collecting annotations on any type of document or visual information from any application. The basis for the system is a screen capture upon which the user can highlight the relevant portions of the image. The user can define any number of topics for organizing notes. Each topic is associated with a highlighting "crayon." In addition the user can supply annotations in digital ink or text. Algorithms are described that summarize captured images based on the highlight strokes so as to provide overviews of many annotations as well as being able to "zoom in" on particular information about a given note and the context of that note.

To enable common mobile terminals to interact with contents shown on large screens, we propose "C-Blink", a new light signal marker method that uses the color liquid-crystal display of a mobile terminal as a visible light source. We overcome the performance limitations of such displays by developing a hue-difference-blink technique. In combination with a screen-side sensor, we describe a system that detects and receives light signal markers sent by cell phone displays. Evaluations of a prototype system confirm that C-Blink performs well under common indoor lighting. The C-Blink program can be installed in any mobile terminal that has a color display, and the installation costs are small. C-Blink is a very useful way of enabling ubiquitous large screens to become interfaces for mobile terminals.

Making effective use of the available display space has long been a fundamental issue in user interface design. We live in a time of rapid advances in available CPU power and memory. However, the common sizes of our computational display spaces have only minimally increased or in some cases, such as hand held devices, actually decreased. In addition, the size and scope of the information spaces we wish to explore are also expanding. Representing vast amounts of information on our relatively small screens has become increasingly problematic and has been associated with problems in navigation, interpretation and recognition. User interface research has proposed several differing presentation approaches to address these problems. These methods create displays that vary considerably, visually and algorithmically. We present a unified framework that provides a way of relating seemingly distinct methods, facilitating the inclusion of more than one presentation method in a single interface. Furthermore, it supports extrapolation between the presentation methods it describes. Of particular interest are the presentation possibilities that exist in the ranges between various distortion presentations, magnified insets and detail-in-context presentations, and between detail-in-context presentations and a full-zooming environment. This unified framework offers a geometric presentation library in which presentation variations are available independently of the mode of graphic representation. The intention is to promote the ease of exploration and experimentation into the use of varied presentation combinations.

We present content-aware free-space transparency, an approach to viewing and manipulating the otherwise hidden content of obscured windows through unimportant regions of overlapping windows. Traditional approaches to interacting with otherwise obscured content in a window system render an entire window uniformly transparent. In contrast, content-aware free-space transparency uses opaque-to-transparent gradients and image-processing filters to minimize the interference from overlapping material, based on properties of that material. By increasing the amount of simultaneously visible content and allowing basic interaction with otherwise obscured content, without modifying window geometry, we believe that free-space transparency has the potential to improve user productivity.

Overview visualizations for small-screen web browsers were designed to provide users with visual context and to allow them to rapidly zoom in on tiles of relevant content. Given that content in the overview is reduced, however, users are often unable to tell which tiles hold the relevant material, which can force them to adopt a time-consuming hunt-and-peck strategy. Collapse-to-zoom addresses this issue by offering an alternative exploration strategy. In addition to allowing users to zoom into relevant areas, collapse-to-zoom allows users to collapse areas deemed irrelevant, such as columns containing menus, archive material, or advertising. Collapsing content causes all remaining content to expand in size causing it to reveal more detail, which increases the user's chance of identifying relevant content. Collapse-to-zoom navigation is based on a hybrid between a marquee selection tool and a marking menu, called marquee menu. It offers four commands for collapsing content areas at different granularities and to switch to a full-size reading view of what is left of the page.

We present the design, implementation, and informal evaluation of tactile interfaces for small touch screens used in mobile devices. We embedded a tactile apparatus in a Sony PDA touch screen and enhanced its basic GUI elements with tactile feedback. Instead of observing the response of interface controls, users can feel it with their fingers as they press the screen. In informal evaluations, tactile feedback was greeted with enthusiasm. We believe that tactile feedback will become the next step in touch screen interface design and a standard feature of future mobile devices.

In this paper we present a system for providing tactile feedback for stylus-based touch-screen displays. The Haptic Pen is a simple low-cost device that provides individualized tactile feedback for multiple simultaneous users and can operate on large touch screens as well as ordinary surfaces. A pressure-sensitive stylus is combined with a small solenoid to generate a wide range of tactile sensations. The physical sensations generated by the Haptic pen can be used to enhance our existing interaction with graphical user interfaces as well as to help make modern computing systems more accessible to those with visual or motor impairments.

We explore the design space of a two-sided interactive touch table, designed to receive touch input from both the top and bottom surfaces of the table. By combining two registered touch surfaces, we are able to offer a new dimension of input for co-located collaborative groupware. This design accomplishes the goal of increasing the relative size of the input area of a touch table while maintaining its direct-touch input paradigm. We describe the interaction properties of this two-sided touch table, report the results of a controlled experiment examining the precision of user touches to the underside of the table, and a series of application scenarios we developed for use on inverted and two-sided tables. Finally, we present a list of design recommendations based on our experiences and observations with inverted and two-sided tables.

We present radial scroll, an interface widget to support scrolling particularly on either small or large scale touch displays. Instead of dragging a elevator in a scroll bar, or using repetitive key presses to page up or down, users gesture anywhere on the document surface such that clockwise gestures advance the document; counter clockwise gestures reverse the document. We describe our prototype implementation and discuss the results of an initial user study.