Debris flow velocity estimation: a comparison between gradient-based method and cross-correlation method

Debris ow causes lot of damages all over the world. The surface velocity of such a natural random ow is one of the important physical parameters that are considered in drawing a hazard map or constructing a sediment control dam. Gradient-based method along with a multiscale smoothing operation nds application in the twodimensional velocity estimation of a debris ow from its video images. This paper investigates the performance of another optical ow determination technique the cross-correlation method in the above application and compares the results with those obtained by the gradient-based method. A computer simulation with synthetic random moving images shows that the accuracy of the cross correlation method is higher than that of the gradient-based method.