Method: Estimating DMV (previous frame, current frame) (a)Pass frames to the Farneback algorithm to estimate the overall motion vector (previous frame, current frame). (b) Apply the following selection criteria: Subtract all vectors with a magnitude <2 pixels $(\Vert {\overrightarrow{\alpha }}_n\Vert <2)$; Subtract all vectors that have a Y component <0 (pointing upwards); Subtract all vectors that have a Y component >0 (pointing downward) that contributes <50% of their magnitude.