Large motion estimation by gradient technique - application to debris flow velocity field

The gradient-based methods that are commonly used for the estimation of two-dimensional velocity field or optical flow behave poorly in the estimation of large motion. A preprocessing multiscale smoothing operation is proposed in the present paper to overcome this problem. Its effectiveness is confirmed by application to synthetic moving images and finally to the velocity field estimation of a natural debris flow along with a gradient-based method known as spatio temporal derivative space method.