Online 3D signature verification by using stereo camera & tablet

The signature of a person is an important biometric attribute which can be used to authenticate human identity. Conventional online approaches to signature verification only use either a single camera to track the pen tip position or a tablet to extract the dynamic features of the signature, hence the signature has only two spatial dimensions. In this paper we combine data inputs from a pressure sensitive device (tablet digitizer) and stereo vision to record signatures in 3D. Stereo vision from a pair of low cost SONY Eyecam cameras is used to track the pen tip position in x, y, & in z when the pen is off the surface as well as the pen angle with respect to the surface at all times. The digitizing tablet on the other hand, tracks x, y as well as pressure magnitude (which we denote as z) when the pen contacts the surface. In all, we record the following parameters as functions of time through the duration of the signature: x;y; z;q;f, where all the linear paramaters are bipolar, with the particular case of z representing motion with positive values and pressure level with negative values. The angular values are two dimensional. The distance between the input signature’s features recorded as a 5-variate parameter time sequence and the template signature’s features whichwere collected during the training phase is computed using Dynamic Time Warping (DTW), and is thresholded to take a decision. While better learning techniques and more intensive experimentation will help suggest improvements, even as of the present, we have a fully working prototype of the system