ESTIMATION OF THE SURFACE VELOCITY OF DEBRIS FLOW WITH COMPUTER-BASEDSPATIAL-FILTERING

A computer-based spatial-filtering velocimeter to measure the surface velocity of natural debris flow is described. This is a simple and int eresting technique implemented with a spatial filter constructed as a software program that processes the video image of debris flow instead of a hardware implementation. The surface velocity of the debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this computer-ba sed spatial-filtering method, and the results were compared with those obtained by a hardware-based spatial-filtering method. Computer-based spatial filtering has the important advantage of a capability for tun ing the spatial-filter parameters to the target flow. (C) 1998 Optical Society of America