DETERMINATION OF THE GEOID HEIGHT (GEOID UNDULATION) BY USING MODERN SURVEYING TECHNOLOGIES

In this work, a large part of Baghdad University campus has been selected. The determination of Geoidal height for the local area requires Ground Control Points which both Ellipsoidal and Orthometric heights are known tocompute the difference between them. The first step of the leveling process began by selected the Ground Control Points (GCPs) around the area of the work, and then divided them into two groups of the network traversestations. They were leveled and adjusted depend on the number of the Bench Marks (B.M.s). Total Station TS (Nikon Nivo 5C) and Global Positioning System (GPS-Garmin 78 map) are used to do this application.The aim of the proposed work was to determine the height of the Geoid surface in the study area. The Geoidal height is calculated from the difference between the two different heights (Orthometric and Ellipsoidal)for the same point and using Geoid Model (EGM) method, then to compare between them. Maximum and the minimum values for the Geoid Undulation are (1.6261 m), and (1.5964 m) respectively with average (1.61 meter) by using (EGM 2008). When it is used the difference method (h-H), maximum and the minimum values for the Geoid Undulation are (5 m), and (2 m)respectively. Finally, the model EGM-2008 represents the best method to determine the Geoid Undulation. dN value between the two different methods is a maximum (3.40) m, a minimum (0.40 m), the average value(1.5 m), and a standard deviation (SD)= ±0.030. At last, image map was produced using Arc GIS 10.1

Keywords:

Geoidal Height , GCPs , Geoid Model , Orthometric , Ellipsoidal , Total Station