A Study of Fitting Local Geoid Model by Weighted Total Least Squares Method-A Case Study of Taichung Area

• Main Authors: Chun-Jia Huang, 黃春嘉
• Other Authors: Szu-Pyng Kao
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/x6k62s

碩士 === 國立中興大學 === 土木工程學系所 === 104 === The aim of the study is to explore how to use the measurements of GPS to obtain the elevation precision that meets the engineering specifications.In this study, we adopt the orthometric heights of first-order leveling data and the ellipsoidal heights that are measured by GPS to fit the local geoid model. Traditionally, the fitting method adopts surface curve fitting method is calculated by least-squares to get the geoid value. Nevertheless, least-squares method can’t deal with the problems which exist in random errors of data in coefficient matrix. Thus, the purpose of this study is to improve the precision of traditional surface curve fitting. We apply both total least-squares and weighted total least-squares which also combined with quadratic polynomial surface curve fitting to improve the random errors of data in coefficient matrix and find the local geoid value with better precision. Combining traditional leveling control points with adjustment in number of fitting points, we obtain an ideal optimal local geoid model that is developed into the elevation precision of ±1.38cm. This study provides not only a fast practical method in getting orthometric heights but also academic references for a different method to fit the local geoid model.