Fig. 4 depicts the general idea of the system. A user interacts with the system by presenting gestures. If the vision subsystem recognizes the gesture then it shares this information with a 3D graphic interface (see also Fig. 5). the most important phases of system development, apart form the software tools selection, were: the choice and adaptation the computer vision algorithms for gesture recognition, determination therapeutic scenarios, and finally software development and integration. The following subsections will give some more details about the system development phases.