Abstract
In applying image-based techniques such as space-time image velocimetry (STIV) to river flow measurements, the images usually taken from a riverbank have to be rectified by using several ground control points (GCPs) set along the river. However, the rectification process sometimes generates erroneous result due to measurement errors of GCP or even when the measurements are correct, the rectified images are difficult to use for a far region due to the lack of enough special resolution. Furthermore, appropriate setting of GCPs becomes difficult for the flow measurement of deep valley. Therefore, we developed an efficient correction method of rectified images by using functional relation of the collinear equation. Moreover, a new method by using a digital clinometer while shooting image is proposed that can reduce the number of GCP in the actual field measurements. An evaluation method for the measurement accuracy of STIV is also proposed.
