Other TableTop Hardware Prototypes

DiamondTouch is just one instance of tabletop hardware, but it has motivated significant exploration of non-hardware aspects of the tabletop interface. It is important to consider alternative hardware in designing a framework for general-purpose tabletop interaction. This subsection gives a brief review of other tabletop hardware prototypes that have been presented in research. The goal here is not to be exhaustive, but to indicate the range and scope of the published work.

SmartSkin SmartSkin [Rekimoto, 2002] is similar to DiamondTouch in its use of capacit- ive coupling. However, receptors are arranged in a grid, rather than a lattice – an 8 × 9 grid of 72, 100 mm square sensors are used in one implementation of SmartSkin, as opposed to 160 + 96 (256), 5 mm-wide strips in DiamondTouch. SmartSkin uses bicubic interpolation of sensor values to effectively increase its resolution, and then image processing techniques to identify points of contact. SmartSkin is also able to detect proximity, leading to a number of interesting hardware applications [Rekimoto et al., 2003]. However, SmartSkin is currently unable to identify to which user a point of contact belongs, making tracking of multiple users problematic and limiting some interaction possibilities.

2.1. The Interactive Tabletop CHAPTER 2. BACKGROUND

Figure 2.1: The 2nd Generation InteracTable, from [Streitz et al., 2002]

Visual Touchpad The Visual Touchpad [Malik and Laszlo, 2004] explores multi-touch gestural interaction and one application developed for it handles picture manipulation. Interestingly, translation and rotation can be accomplished with a single finger and in the same movement by rotating the finger itself. This is achieved solely through image processing – the Touchpad itself is just a piece of paper. However, in the reported implementation, this means an image cannot also be projected onto the surface, so the interaction is indirect, making use of a vertical display. Also, multiple users are not supported.

FTIR Displays Han [2005] uses a technique called Frustrated Total Internal Refelec- tion (FTIR), which is force-sensitive, and provides high resolution and scalability. One implementation uses a drafting table style measuring 36 x 27 inches with rear projection and has a sensing resolution of better than 0.1 inches at 50Hz. Stroke event information is sent to applications using the OSC protocol over UDP. Current publications have only discussed the hardware. A number of demonstrator applications have been developed, but not released publicly. More information is available2.

Lumisight The Lumisight table [Matsushita, Iida, Ohguro, Shirai, Kakehi, and Namemura, 2004] is a rear-projection tabletop featuring four LCD projectors and a special tabletop surface, which transmits light from each projector only in a specified direction. Thus four users may sit at the table and each may see a different image rear-projected onto the table. It is not a touch interface – currently users must use traditional input devices – keyboards, mice and sometimes joysticks. Lumisight is a heavyweight solution to the

problem of providing private information on the tabletop display.

Work using Lumisight has analysed the behaviour of users and how the group experience changed when using the shared tabletop rather than four traditional upright displays. In the context of a “catch the fugitive” collaborative maze game, Matsuda et al. [2006] found that “membership closeness enhances the performance advantage of the Lumisight table” (i.e.

people familiar with each other interact more efficiently). This is an interesting observation, that should be considered when formulating user studies, for tabletop interfaces.

InteracTable Part of the i-LAND project [Streitz et al., 1999] from the Ambiente Lab at the Fraunhofer ISPI, the InteracTable is intended as a commercially viable interaction device for face-to-face collaboration in a work environment [Streitz, Tandler, Müller-Tomfelde, and Konomi, 2001]. The 2nd Generation InteracTable [Streitz et al., 2002] is shown in Figure 2.1.

Streitz et al. [1999] coin the term Roomware®_{, defined as the result of integrating}

information and communication technology in room elements such as doors walls and furniture. Along with their InteracTable®, they also present the DynaWall®, CommChair® and ConnecTable®_{; supported by their software BEACH, a cooperative hypermedia envir-}

onment; MagNets, a creativity tool built upon BEACH and; PalmBench, an application for a PDA, allowing information to be “intuitively beamed” to the DynaWall [Streitz et al., 2002]. The BEACH framework is discussed further under in Section 2.3.5.

u-Texture The u-Texture is a self-organisable touch-sensitive panel, which can be con- nected to other u-Texture panels by “non-expert” users to create smart surroundings. Each panel changes its own behaviour, based on its location, inclination and the location of surrounding panels. One mode provided is the CollaborationTable, initiated when panels are connected horizontally (e.g. in a square). Users can then share media items from their own panel with neighbouring panels, by dragging the items to the edge of their screen.

Distributed Tabletops

Another important area of tabletop research investigates the support they may provide for

distributed collaboration.

The goal of the AugmenTable is “to take advantage of designers’ working habits in horizontal surfaces to facilitate the transition between the tangible intermediary objects and the existing digital environments of the company” [Perron and Laborie, 2006]. The design team was split between Stanford in the USA and Tolouse in France and so the platform has also been designed to support geographically distributed design activities. The AugmenTable is not an input device – wireless keyboards and mice are used, as well as an eBeam wireless stylus, to interact with it. The Stanford AugmenTable has two sets of keyboards and mice at opposite sides of the table, but the software support for this hardware is not discussed. Distributed applications are still being designed – Perron and Laborie [2006] present some foreseen interaction possibilities.

ViCAT is a research project at the National ICT Australia whose aim is to allow “intense” collaboration between multiple users at geographically distributed sites [Chen et al., 2006]. The intention is to give the impression of having all the users gathered around a single table. The current focus is on videoconferencing and collaborative control of traditional input methods (i.e. keyboard and mouse), and has grown into the Braccetto project.