ToF Cameras and Microsoft Kinect Depth Sensor for Natural Gesture Interfaces

Natural computer-human interfaces are gaining more and more importance everyday. Users would ideally like to communicate with machines in a natural way, i.e., by means of voice or gestures. Concerning the latter, a natural inteface should be able to correctly identify gestures without the presence of a physical controller such as a mouse, a track-pad or a Nintendo WiiMote. Interfaces of this kind in practice require the acquisition and the analysis of 3D data from dynamic scenes, which has always been a very challenging problem. Until a few years ago this was possible only with complex and expensive setups. Recently, novel acquisition devices such as Time-of-Flight (ToF) range cameras have made this task almost as simple as acquiring a standard video of the scene. Furthermore, the introduction of the Microsoft Kinect device has made this technology available to the mass market at a very low price. This paper after a quick review of the technology behind ToF cameras and the Kinect device, introduces a mathematical model of the errors in the measurement process. The measurement errors and the artefacts in the acquired data are analysed in detail for the two devices upon a wide set of experiments showing the performance of these devices in dierent conditions.