In our previous studies into web design , we found that pens, paper, walls, and tables were often used for explaining, developing, and communicating ideas during the early phases of design. These wall-scale paper-based design practices inspired The Designersí Outpost , a tangible user interface that combines the affordances of paper and large physical workspaces with the advantages of electronic media to support information design. With Outpost, users collaboratively author web site information architectures on an electronic whiteboard using physical media (post-it notes and images), structuring and annotating that information with electronic pens. This interaction is enabled by a touch-sensitive SMART board augmented with a rear-mounted video camera for capturing movement and a front-mounted high-resolution camera for capturing ink.
The electronic representation gives us three main advantages: the ability to support fluid transitions to other tools, such as DENIM , support for history , and remote collaboration .
We have recently developed a remote collaboration system  based on The Designersí Outpost. The system provides a distributed shared workspace that employs physical post-it notes as interaction primitives. We implement and evaluate two mechanisms for awareness: transient ink input for gestures and a blue shadow of the remote collaborator for presence.
Figure 1: Users collaborate remotely using physical artifacts. Notes that are digital on this board correspond to electronic notes in Figure 2.
Figure 2: Notes on this board are electronic versions of the physical notes in Figure 1.