Adaptive computer-based spatial-filtering method for more accurate estimation of the surface velocity of debris flow

An adaptive computer-based spatial-filtering velocimeter to measure the sur face velocity of a natural debris flow with high accuracy is described that can adjust the filter parameters, specifically, the slit width of the filt er, based on the surface-pattern characteristics of the flow. A computer si mulation confirms the effectiveness of this technique. The surface velocity of a natural debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this adaptive method, and the results were compared with those obtained by two other methods: hardware-based spatial filtering and normal computer -based spatial filtering. (C) 1999 Optical Society of America OCIS codes: 0 70.6110, 100.2000, 280.7250.