Camera Control in a Planar, Graspable Interface

BUILD-IT is a planning tool based on computer vision technology, supporting complex planning and composition tasks. It allows a group of people, seated around a table, to interact with objects in a virtual scene using real bricks. A plan view of the scene is projected onto the table, where object manipulation takes place. Hence, manipulation and display are coincident. A perspective view is projected on the wall, controlled by a brick acting on a virtual camera. The camera requires control of position, pan, tilt, zoom and roll attributes. However, planar interaction with bricks provides only position and rotation information. The topic of this paper is how to bridge the gap between planar interaction and three dimensional (3D) camera control. This is done by introducing additional, active objects whose positional relation to the camera controls the above attributes.