| Summary: | 碩士 === 國立中興大學 === 土木工程學系 === 90 === The main goal of this research is to determine the orthometric height correction by using gravitational observations of the first-order precise leveling staff setting up spots between precise benchmarks. In preceding research, the orthometric height correction computation just used the gravitational observations of benchmarks. Is it suit for orthometric height correction? It neglects the effect of the terrain and the change of the elevation. In this research, using four sets of the first-order leveling and gravitational data that represents different terrain compute orthometric height correction, then compares orthometric height correction results of just using gravitational observations of benchmarks with using gravitational observations of staffs setting up spots between precise benchmarks. If two sets of results are equal to each other or the difference under the criteria of the first-order precise leveling, it will prove the model of computing orthometric height correction using gravitational observations of benchmarks is correct. In this dissertation, also using the new Free-air anomaly grid data of Taiwan Island interpolate and derive the Bouguer anomaly and gravity, then uses data to calculate the orthometric height correction. Evaluating the result of interpolating to find a model which save time and budget for doing orthometric height correction.
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