Ortholumen is based on using visible light source(s) that are manipulated in the space above the table. Since light sources are defined by their position, orientation, and direction in space, they may give additional DOFs to tabletop input.

Ortholumen is a light pen based tabletop interaction system that can employ all the pen's spatial degrees of freedom (DOF). The pen's light is projected from above onto a horizontal translucent screen and tracked by a webcam sitting underneath, facing upwards; system output is projected back onto the same screen. The elliptic light shape cast by the pen informs the system about pen position, orientation, and direction. While this adds up to six DOFs, we have used up to four at a time. In order to separate input and output light we employ polarizing filters; on the webcam and on the projector lens. Two prototypes, painting and map navigation, are presented. Ortholumen can be expanded to track multiple pens of the same or different colors; this enables bi-manual input, collaboration, and placed pens as external memory. Visible light, as opposed to infrared or radio, may be perceived as more directly by users. Ortholumen employs only low-cost parts, making the system affordable to home users.

Publications or Reports

  • Holger Tiedemann. 2010. Head Tracking Based 3D Illusion And Possibilities Of Interaction On Tabletop Systems. Master thesis, Chalmers/Hochschule der Medien Stuttgart, Computer Science and Media. 
  • T. Piazza and M. Fjeld. 2007. Ortholumen: Using Light for Direct Tabletop Input. Second Annual IEEE International Workshop on Horizontal Interactive Human-Computer Systems (Tabletop 2007). PP. 193-196.   
Project Status

Not currently active

Former workers: Morten Fjeld, Hannes Heller, Tommaso Piazza