2002 Volume 46 Pages 821-826
A new one-dimensional velocity measurement method using image analysis was developed. In this method, image intensity distribution for a line specified in the mean flow direction on a flow video image was cumulated in the temporal direction, thereby creating a spatiotemporal image with a striped pattern indicating the mean velocity on the specified line. The striped pattern is created due to the convection of image intensity conveyed by the mean flow. This method is applicable to river surface images videotaped from a riverbank during flood. Since the images are distorted the spatial resolution in the far field is relatively low; however, the presented method showed a favorable performance in the measurement of flood surface flow of the U River. The result was compared with that by the large-scale particle image velocimetry (LSPIV) and the new method's superiority was verified. Also a method for improving mapping relationship between the CRT coordinates and the physical coordinates was demonstrated.
