DiamondTouch

DiamondTouch is a touch input device developed by Mitsubishi Electric Research Laborat- ories (MERL) and is an example ofSingle Display Groupware (SDG)[Stewart et al., 1999], a term used to describe most current tabletop interfaces. It was developed by Dietz and Leigh [2001] as a prototype, and is now available for purchase. However, at this stage units are hand fabricated and costly (over US$10 000).

DiamondTouch supports arbitrary parts of the body being used to interact with the display. In practise, two hands, fingers, thumbs or palms are typically all that are used. When users touch the DiamondTouch, weak electric signals for the row(s) and column(s) with which they make contact are transmitted through each of their bodies to grounding pads upon which they sit. In this way, DiamondTouch supports multiple users unambiguously. That is, it can identify which user’s hands are touching the surface, as well as where they touch.

DiamondTouch is particularly noteworthy because of its support for multiple touches, as well as being able to distinguish the user to which the touch belongs. It is also one of the most mature tabletop hardware platforms, and has been used for a number of tabletop studies. This subsection will also discuss some of these studies, as they are useful to inform the design of PhoTable.

Group Size and Table Size

One potentially important property of a table is its size: it may be that this affects the quality and effectiveness of interaction. This has been explored in one study by Ryall, Forlines, Shen, and Morris [2004] who explored the effects of group size and table size with interactions on the DiamondTouch and a version of the Poetry Table application. This

2.1. The Interactive Tabletop CHAPTER 2. BACKGROUND

displays a number of words, each in a box, arranged in circles around the table and allows the construction of a poem, by dragging words into a container; aligning the words. A total of 45 participants aged 18 to 25 were recruited from universities and organised into groups of two, three and four.

After being given instructions and allowed to experiment with the interface until they were comfortable, participants were asked to collaboratively “build the printed poem as quickly and accurately as you can”. They found that table size (either 80cm or 107cm across the diagonal) had no statistically significant effect on the task, but groups with more people were able to construct the poem more quickly. However, they did discover that users felt that the larger table was better for the task. These observations may be relevant when sharing photographs, but our sharing task is typically driven by the storyteller and these results may not be applicable as there is no time pressure in our task. This study also focused on a single task, and the findings may not generalise to other tasks, bigger differences in table size, and other factors.

Object Ownership

Because DiamondTouch is able to reliably identify the user to whom a touch belongs, it is an attractive interface to explore techniques that involve enforcing ownership of virtual objects.

In the investigation of techniques for transferring ownership of items projected on the tabletop surface, Ringel, Ryall, Shen, Forlines, and Vernier [2004] conducted an evaluation with DiamondTouch. They found that their “Relocate” sharing technique was both more efficient and less error prone, as well as preferred, over their “Resize”, “Reorient” and “Release” techniques.

The relocate technique is similar to the basic technique for sharing private objects in Cruiser; using personal spaces and leveraging DiamondTouch to enforce permissions in one study [Apted et al., 2006]. In the more recent PhoTable experiments, private spaces were not explored. However, with DiamondTouch hardware, the Cruiser framework would, for example, be able to let only the owner of a photograph extract it from a browsing object, in order to share it. This suggests a fifth technique to consider. That is, allowing only the owner access to interface objects that create sharable objects.

Interaction with Other Devices

Often there is a desire to move data onto or off the tabletop interface, as a tabletop’s immersive nature is not suited to some interactions (e.g. those requiring a keyboard). Alternatively, there may be a desire for media created on the tabletop to be presented or shared on other devices.

MultiSpace [Everitt, Shen, Ryall, and Forlines, 2006] aims to explore the role of the interactive tabletop for the coordination of electronic media in multi-device environments. Using the table as a central hub of a meeting room, electronic documents can be distributed among meeting participants at a tabletop as well as on wall displays via an application built with DiamondSpin (§2.3.1). Media is transported using object Containers and DocuBits; a portion of captured screen area and associated editable text.

Cruiser does include some methods for interaction with other devices beyond merely providing input. However, it is not a focus of the framework, which first aims to provide immersive interaction on a single device. Importing media from digital cameras and other removable storage, and export of on-screen objects to a wall display (§4.4.3) is currently supported. However, the protocol used is not yet formalised.

Other DiamondTouch work continues the effort to coalesce work on multi-surface, multi-device visualisation groupware into a framework called DiamondSpace1 [Shen, 2006]. Searching and Tagging

Morris, Paepcke, and Winograd [2006a] present TeamSearch, a way of specifying metadata tags in a search using fixed, discrete search terms and “query tokens”. Participants form search criteria by individually moving their tokens onto the search terms. Results are shown in front of each user – either collectively, with all users’ terms satisfied in all results displayed; or in parallel, with each user being presented search results from only the terms they had specified.

Related to this is TeamTag [Morris et al., 2006b], which uses a modified interface targeted at supporting collaboration among bio-diversity researchers. The tags that may be chosen are assigned to photographs by touching the textual tag after first selecting the photograph. Tagging could be performed concurrently by all participants. Performance with a shared source for tags was compared with a variation where each participant had their own source of tags.

Searching and tagging are applications that were considered when developing Cruiser, and novel approaches using Cruiser were explored in two Honours’ projects (see §6.2). When considering the PhoTable application, such tasks are clearly relevant for managing personal collections of digital photographs. However, PhoTable uses a more subtle approach to search and assigning metadata (§4.5) and does not profess to be an application to manage photo collections (see also §2.4.1Photo Sharing Applications).

Other DiamondTouch Applications

Ryall, Morris, Everitt, Forlines, and Shen [2006] summarise their informal observations of tabletop use, by users visiting their lab on a wide range of applications. Applications include LobbyTable, a set of games running on a coffee table in the lobby of MERL; and; DTLens, a 2D map browsing application, with lenses showing overlaid metadata [Forlines and Shen, 2005]. They present an extensive set of observations to complement published controlled user studies.