サンゴ礁海域を対象とした写真測量（測深）法の開発

Abstract

A nearshore zone characterized by coral reef has so much potential for fish habitat, marine activity and other ecological and recreational functions. However, a subaerial survey with high special resolution is still hard to conduct in the nearshore zone yet especially in depths shallower than several meters. Therefore, an aerial photogrammetry method is applied to a nearshore survey at Yoshiwara beach in Ishigakijima Island, Okinawa. The method uses a digital still camera with nearly 8 mega pixels of resolution and a series of aerial photographs of carbonate beach and coral reef which were taken from a Japan Coast Guard (JCG) helicopter. The original digital photograph is then modified to an orthogonal image by using some new techniques. In addition, a set of nearshore topography data surveyed by an aerial laser system had been applied as a reference data. The resulting map shows a typical character of real coral reef topography although there are some inconsistencies. Thus, in general the current method can be applicable to a nearshore survey with good cost performance.