Height modernization using fitted geoid models and myrtknet

Abstract

The purpose of this study is to examine the strategies for rapid height determination using the current Global Positioning System (GPS) technology. With steady economic growth in Malaysia since 1998, more highways, federal and states road have been built or have been widen. These development processes have somehow destroyed, damaged or disturbed the levelling benchmarks located along the routes. Currently the conventional method to require the levels of these benchmarks is costly and time-consuming. This study focuses on the theory, computation method and analysis of WMGeoid04 and WMGeoid06A revised models using GPS Virtual Reference Stations (VRS) technique for rapid height determination. The computation of WMGeoid04 and WMGeoid06A precise fitted geoid models was based on least squares collocation using the existing gravimetric geoid and newly observed geometric geoid separation. Analysis of the precise fitted geoid models have shown that the formal fitting errors were less than 4 cm. In addition, the validation process with external data sets has achieved 5 cm accuracy in terms of Root Mean Square (RMS). Assessment of GPS station coordinate consistency indicates the achievable accuracy (at 95% confidence region) from VRS technique is better than 3 cm horizontally, and better than 6 cm vertically. Further analysis using orthometric height comparison between published and derived height of levelling benchmarks using the combination of fitted geoid models with VRS technique have shown that the differences are better than 6 cm. The results showed that GPS levelling with precise fitted geoid model and VRS technique is relatively better than second class levelling survey at a lesser cost and time, and could be used to update existing levelling benchmark and establishing a new levelling routes in Malaysia.