We present an experimental comparison of multi-touch and tangible user interfaces for basic interface actions. Twelve participants completed manipulation and acquisition tasks on an interactive surface in each of three conditions: tangible user interface; multi-touch; and mouse and puck. We found that interface control objects in the tangible condition were easiest to acquire and, once acquired, were easier/more accurate to manipulate. Further qualitative analysis suggested that in the evaluated tasks tangibles offer greater adaptability of control and specifically highlighted a problem of exit error that can undermine fine-grained control in multi-touch interactions. We discuss the implications of these findings for interface design.

There is growing interest in tabletop interfaces that enable remote collaboration by providing shared workspaces. This approach assumes that these remote tabletops afford the same beneficial work practices as co-located tabletop interfaces and traditional tables. This assumption has not been tested in practice. We explore two such work practices in remote tabletop collaboration: (a) coordination by territorial partitioning of space; and (b) transitioning between individual and group work within a shared task. We have evaluated co-located and remote tabletop collaboration. We found that remote collaborators did not coordinate territorially as co-located collaborators did. We found no differences between remote and co-located interfaces in their ability to afford individual and group work. However, certain interaction techniques impaired the ability to transition fluidly between these working styles. We discuss causes and the implications for the design and future study of these interfaces.

Displaying small text on large multiprojector tiled displays is challenging. Problems arise because text is badly affected by the image-warping techniques that these displays apply to rectify projector misalignment. As a consequence, there has been little progress with important large-display applications that require small text, such as collaborative tutoring or Web-browsing. In this paper we present a new warping technique designed to preserve crisp text, based on recent work by Hereld and Stevens. Our technique produces good results, free of artifacts, when used in today's multiprojector displays. We evaluate the legibility of our technique against conventional interpolation-based warping and find that users prefer our technique. We describe an efficient and reusable implementation, and show how the increased legibility has allowed us to investigate two new applications.