www.dgp.toronto.edu Recent advances in sensing technology have enabled a new generation of tabletop displays that can sense multiple points of input from several users simultaneously. However, apart from a few demonstration techniques [17], current user interfaces do not take advantage of this increased input bandwidth. We present a variety of multifinger and whole hand gestural interaction techniques for these displays that leverage and extend the types of actions that people perform when interacting on real physical tabletops. Apart from gestural input techniques, we also explore interaction and visualization techniques for supporting shared spaces, awareness, and privacy. These techniques are demonstrated within a prototype room furniture layout application, called RoomPlanner.

DiamondSpin is a toolkit for the efficient prototyping of and experimentation with multi-person, concurrent interfaces for interactive shared displays. In this paper, we identify the fundamental functionality that tabletop user interfaces should embody, then present the toolkit’s architecture and API. DiamondSpin provides a novel realtime polar to Cartesian transformation engine that has enabled new, around-the-table interaction metaphors to be implemented. DiamondSpin allows arbitrary document positioning and orientation on a tabletop surface. Polygonal tabletop layouts such as rectangular, octagonal, and circular tabletops can easily be constructed. DiamondSpin also supports multiple work areas within the same digital tabletop. Multi-user operations are offered through multithreaded input event streams, multiple active objects, and multiple concurrent menus. We also discuss insights on tabletop interaction issues we have observed from a set of applications built with DiamondSpin.

Researchers seeking alternatives to traditional desktop computers have begun exploring the potential collaborative benefits of digital tabletop displays. However, there are still many open issues related to the design of collaborative tabletop interfaces, such as whether these systems should automatically orient workspace items or enforce ownership of workspace content. Understanding the natural interaction practices that people use during tabletop collaboration with traditional media (e.g., pen and paper) can help to address these issues. Interfaces that are modeled on these practices will have the additional advantage of supporting the interaction skills people have developed over years of collaborating at traditional tables. To gain a deeper understanding of these interaction practices we conducted two observational studies of traditional tabletop collaboration in both

Previous research has shown that rotation and orientation of items plays three major roles during collaboration: comprehension, coordination and communication. Based on these roles of orientation and advice from kinesiology research, we have designed the Rotate’N Translate (RNT) interaction mechanism, which provides integrated control of rotation and translation using only a single touch-point for input. We present an empirical evaluation comparing RNT to a common rotation mechanism that separates control of rotation and translation. Results of this study indicate RNT is more efficient than the separate mechanism and better supports the comprehension, coordination and communication roles of orientation.

Despite the mobility enabled by the plethora of technological tools such as laptops, PDA and cell phones, horizontal flat surfaces are still extensively used and much preferred for on-the-move face-to-face collaboration. Unfortunately, when digital documents need to be shared during collaboration, people are still mostly constrained to display surfaces that have been designed for single users, such as laptops and PDAs. Technologically there is a lack of computational support for shared digital document access, browsing, visualization and manipulation on horizontal surfaces. We believe support for such serendipitous meetings will play a critical role in future ubiquitous computing spaces. Our UbiTable project examines the design space of tabletops used as scrap displays. Scrap displays support kiosk-style walk-up interaction for impromptu faceto -face collaboration. Our design offers the affordances of a physical table. It provides the flexibility by allowing users to layout shared documents with desired orientation and position; at the same time it augments traditional paper-based interactions by providing a flexible gradient or shades of sharing semantics. UbiTable addresses visual accessibility vs. electronic accessibility of documents, an issue which is critical to ubiquitous environments.

Interactive tabletops have been previously proposed and studied in the domain of co-located group applications. However, little fundamental research has been done to explore the issue of size. In this paper we identify a number of size considerations for tabletop design, and present an experiment to explore some of these issues, in particular the effects of group size and table size on the speed at which the task was performed, the distribution of work among group members, issues of shared resources, and user preference for table size. Our findings shed light on (1) how work strategies are affected by group size, (2) how social interaction varies with respect to table size, and (3) how the speed of task performance is influenced by group size but not by table size. In addition, our experiments revealed that for larger groups, designers might need to add additional vertical displays for shared information. This finding opens the door for extending singledisplay groupware to shared-display groupware settings that involve multiple, shared displays.

This paper presents visualization and layout schemes developed for a novel circular user interface designed for a round, tabletop display. Since all the displayed items are in a polar coordinate system, many interface and visualization schemes must be revisited to account for this new layout of UI elements. We first discuss the direct implications of such a circular interface on document orientation. Then we describe two types of fisheye deformation of the circular layout and explain how to use them in a multiperson collaborative interface. These two schemes provide a general layout framework for circular interfaces. We have also designed a new visualization technique derived from the particularities of the circular layout we have highlighted. In this technique the user control the layout of the elements of a hierarchical tree. Our approach is not to automatically compute the most effective position of the nodes and leaves of a tree but to provide the user rich interaction possibilities to easily and quickly produce a layout comparable to the hyperbolic view developed at Xerox PARC. Finally, we discuss future work and possible visualization techniques based on different information structures.

In ubiquitous computing environments, multiple users work with a wide range of different devices. In many cases, users interact and collaborate using multiple heterogeneous devices at the same time. The configuration of the devices should be able to change frequently due to a highly dynamic, flexible and mobile nature of new work practices. This produces new requirements for the architecture of an appropriate software infrastructure. In this paper, an architecture designed to meet these requirements is proposed. To test its applicability, this architecture was used as the basis for the implementation of BEACH, the software infrastructure of i-LAND (the ubiquitous computing environment at GMD-IPSI). It provides the functionality for synchronous cooperation and interaction with roomware components, i.e. room elements with integrated information technology. In conclusion, our experiences with the current implementation are presented.

This research explores distributed sensing techniques for mobile devices using synchronous gestures. These are patterns of activity, contributed by multiple users (or one user with multiple devices), which take on a new meaning when they occur together in time, or in a specific sequence in time. To explore this new area of inquiry, this work uses tablet computers augmented with touch sensors and twoaxis linear accelerometers (tilt sensors). The devices are connected via an 802.11 wireless network and synchronize their time-stamped sensor data. This paper describes a few practical examples of interaction techniques using synchronous gestures such as dynamically tiling together displays by physically bumping them together, discusses implementation issues, and speculates on further possibilities for synchronous gestures.

Interactive tables can enhance small-group colocated collaborative work in many domains. One application enabled by this new technology is copresent, collaborative search for digital content. For example, a group of students could sit around an interactive table and search for digital images to use in a report. We have developed TeamSearch, an application that enables this type of activity by supporting group specification of Boolean-style queries. We explore whether TeamSearch should consider all group members ’ activities as contributing to a single query or should interpret them as separate, parallel search requests. The results reveal that both strategies are similarly efficient, but that collective query formation has advantages in terms of enhancing group collaboration and awareness, allowing users to bootstrap query-specification skills, and personal preference. This suggests that team-centric UIs may offer benefits beyond the “staples ” of efficiency and result quality that are usually considered when designing search interfaces. 1.