1. A method for interfacing with a machine using a virtual input device, said method comprising: receiving from an image feed device an image in which a hand is present; detecting fingertips of the hand in said image; establishing a candidate vector signature for said fingertips based on the relative position of each fingertip with respect to a reference axis defined by the remaining fingertips; comparing said candidate vector signature to pre-stored vector signatures representing classified hand postures, the pre-stored vector signatures being mapped to a multidimensional space; estimating, for each class of the pre-stored hand postures a probability that the candidate vector signature belong to this class; determining a hit state using the probabilities associated with the candidate vector signature and probabilities associated with previous vector signatures of a previous images; associating the hit state to a virtual key in a first row of the virtual input device; sending a function represented by said virtual key to said machine for execution.