Using B-Spline Surface to Represent and Update Taiwan Geoid Model

• Main Authors: Chi-Kung Chu, 儲繼光
• Other Authors: Ming Yang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/19337983085237222475

碩士 === 國立成功大學 === 測量及空間資訊學系碩博士班 === 93 === ABSTRACT Recently,according to the high precision Taiwan Vertical Datum system had been established at 2001(TWVD2001),the system combined GPS/levelling/geoid height Network adjustments,and used the way of least-square-collocation-with-unknown-parameters to complete the new Taiwan geoid grid data.The research chooses the optimal B-Spline control points and order of B-Spline curve,and uses “Approximation B-Spline”to get the best fitting B-Spline surface model.The model take geoid grid data as an afterward processing,and analyzes the precision of interpolation、 model storage and the results of updating model resolution with new observations. According to the experiment,there is a distinguished improvement when spline interpolation is compared to bilinear interpolation in the infrequent grid data,especially in the mountain area.It can explain that spline interpolation is better than bilinear interpolation in the more flexuous area。Besides,B-Spline model can compress the larger storage capacity grid data like 3"grid data into 25%.On the part of updating with new observations,we can analyze that the update range is in inverse proportion to the precision of interpolation.For considering update range and the precision of interpolation,the update range about 4KM is proper,however,different update range has different improve ratio,the larger update range has smaller improve ratio;on the contrary,the smaller update range considers the local quality and the improve ratio is less obvious.