The orthometric height of points is needed in civil engineering projects (i.e., the height of
points above geoid). Geoid undulation (the difference between an ellipsoid and a geoid
surface)[1], [2] must be understood to use the Global Navigation Satellite System (GNSS) in
engineering surveying. The geometric approach was used to attempt to calculate the geoid
undulation. In this study. For local geoid determination, by using a data matrices method. The
geoid model was determined using geoid undulation of GPS/Levelling points considering the
Global Geopotential Model (GGM) and Residual Terrain Model (RTM) effects at these
stations. this technique has been compared by the value of mean and standard deviation and
known geoidal heights values from GPS leveling for testing points to determine the accuracy
of this method. The results demonstrate that the data matrices' accuracy is extremely low.