This processor computes the velocity based on pedestrian positions and the simulation time. Let p be the position of a pedestrian at the current time step s. And let q be the position of the same pedestrian at the time step s minus backSteps then the velocity of this pedestrian at the time of time step s is defined by: the length of the vector q-p divided by the duration between s and (s minus backSteps). @author Benedikt Zoennchen