A spatial tracked touch screen for computer aided sketching

This paper describes the development of an innovative harware and software tool useful to sketch planar shapes in Computer-Aided Industrial Design and Computer Aided Design systems. The whole system is composed by a portable hand-held small touchscreen, a large fixed main screen and an optical tracking equipment. The touch-screen is added by a simple camera for Mixed Reality optional functionality and its 6 degrees of freedom movements are tracked through four groups of Light Emitting Diodes located on back of the monitor. A Nintendo WiiMote with infrared camera is used to acquire Light Emitting Diodes relative positions for real-time tracking. A 6 degrees of freedom Inertial Measurement Unit has been added to improve the stability of the pose estimation: an Extended Kalman Filter provides the data fusion. Furthermore, a custom software has been implemented for optimal exploitation of a such configured hardware and facilitate input and 3D sketching. The physical tablet can be used in three different ways: as a 3D mouse which sets the point of view of the main screen according to its attitude, to set a plane in the main screen so that a 2D sketch can be referenced in the 3D space and as a support device to improve the manual draw of an object by overwriting the image contour. The results obtained confirms the usefulness of the virtual tablet in design, modelling, and reverse engineering of industrial products.