模型飛行機材と航空写真技術を用いた積雪観測法の開発

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Sufficient data on roof snow loads for structural design are not available because there is difficulty in measuring the intensity and distribution of snow load by climbing onto roofs. This research develoiped an efficient and accurate method for surveying roof snow loads by adopting an aerial photogramtry. In the previous study, the authors had clarified the measurement accuracy of aerial photogramtry using mainly airplane for surveying roof snow and had shown the probability of this merthod for snow survey. A chartered flight for aerial survey, however, is very expensive and it is inconvenient that users can not operate the airplane nor camera by themselves. Therefore the authors developed the aerial photogramtry using a kite balloon as a carrier of camera in order to solve these problems.In the study, the performances of the kite balloon system and unmanned-radio control helicopter system were compared with the case using airplane as the carrier, and the measurement accuracy of the n … More ew systems was discussed because the quality of the camera hanged on the balloon was different from that on airplane. The results are as follows :1) The results of comparison among the features of aerial photography usig airplane, kite balloon and model helicopter, showed that the advantages of three different aircrafts made up disadvantages of each other. Therefore, users should properly select the best system in consideration of geographical conditions of a site, surroundings of a object, total number or duration of observations, expenses for measurements and so on.2) The kite balloon aerial photography system is enough for practical use to survey roof snow depths because the measurement accuracy is allowable and the cost performance was the best among the three systems.3) The way of using a polaroid filter as the counterplan against halation shows the best performance in practical use because this way can avoid occurring halation for almost any sunlight conditions and does not restrict the photographing within limited time.4) The distributions of snow depths on roofs of large buildings were investigated by the se systems and were discussed on effect of average wind direction. Less