The inertial navigation system (INS) is an efficient navigation method but it can occur accumulative errors. To correct
this error in the INS, this paper presents a novel optical-flow aided navigation method by studying the terrain aided
navigation, which can implement the continuous error estimation of the INS by employing the extended kalman filter
that regards optical-flow as its measurement parameter. Therefore, this aided method is similar to the terrain aided
navigation except that the measurement parameter and equation are both derived from optical-flow instead of terrain
height. Experiments with some actual aerial image sequences have proven the efficiency of this aided navigation method.