Drawing in Space using the 3D Tractus

The 3D Tractus (Latin for drawing, space and movement) is a simple and inexpensive physical interface for intuitive and direct exploration, manipulation and inputting of three-dimensional (3D) data. The interface is a straightforward evolution of the non-computerized drawing board, preserving the drawing board physical spatial affordances and enhancing it by allowing the interactive planar surface to be easily moved along the z-axis. The 3D Tractus maintains direct spatial mapping between the physical and virtual spaces by allowing planar interaction on the surface and sensing its height. Much like the drawing board, the first prototype of the 3D Tractus was designed for sketching and drawing applications. The interface can be useful in various tasks that approach 3D space via two-dimensional (2D) planar interaction metaphors, such as evaluation and analyses of 3D medical imaging data. In this paper we present the 3D Tractus design principles and the implementation of its early prototype.