DOI: 10.36347/sjet.2018.v06i12.006

Pages: 410-416

The principal purpose of this research is to employ the GPS observations to predict the orthometric height. Specialist software such as MS-Excel has been used to develop the required regression models. Vertical control points within the network that include ellipsoidal, orthometric and geoid height data were investigated. Although the theoretical relationship between these height types is simple in nature, discrepancies among the combined height data and its practical implementation have proven to be quite challenging due to numerous factors. Two primary challenges have been chosen as research objectives; (i) developing a mathematical model to compute the geoid undulation from GPS and precise leveling, (ii) correcting the observed geoid undulation by least square method. To address these objectives, a general empirical-based procedure has been adopted with statistical analysis for assessing the performance of the selected parametric models. Additional numerical studies included the obtaining of geoid models (local geoid), scaling the GPS-derived ellipsoidal height matrix, and evaluating the orthometric heights obtained from national/regional adjustments of leveling data. Finally, the orthometric height results obtained from the developed mathematical and adjustment models can be adequately and reliably used for the city of Baghdad.