An investigation of the criteria used to select the polynomial models employed in local GNSS/leveling geoid determination studies

Abstract

Ellipsoidal heights are determined with high accuracy using Global Navigation Satellite System (GNSS) techniques. In infrastructure projects undertaken for engineering purposes, orthometric heights are used. Geoid determination studies based on these two height systems are growing in importance. Although various methods are employed in geoid determination, one of the most commonly used in practice is local geoid determination. Points with known orthometric and ellipsoidal heights are used as reference points. These reference points are utilized to determine local geoid models for project area. The formation and selection of the most appropriate and true-to-reality model during modeling are a matter of extreme significance for practitioners who employ such models. In this study, we aim to establish a GNSS/leveling geoid in a test network that was formed in Konya for the purpose of local geoid determination. Validity tests are carried out for five different geoid models. These geoid models are determined using polynomial models of up to the third degree, and an exploration of the parameters that could be used in the decision-making process is performed. In accordance with the results of these calculations, the selection of an appropriate model among different potential polynomial models in local geoid modeling is explained in terms of theoretical references, an application is examined using the data from the study area, and the results are compared.