At close range, the oblique perspective has proved flexible for deriving water surface data using photogrammetry. Accuracies of between 0.12 and 0.36m were achieved. The river was in spate following snowmelt, this provided natural texture suitable for automated DEM extraction. Perhaps the most ambitious, although expensive example is that achieved by Yamazoki et al., (1998), who obtained synchronized imagery from two aircraft flying above the Ishikon River in Japan. They measured natural standing water features called “wrack lines”, but although valuable for determining river elevation at a point, were insufficient in number to provide a true surface. ![]() At the small scale, Lane et al., (2003) use scanned aerial photography at 1: 4500 scale to yield water level estimates to a precision of ☐.15m on a flooding river in northern England. Working in the more uncontrolled field environment is more challenging and photogrammetric based systems have been utilized at a range of scales.
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