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Research Paper | Civil Engineering | Botswana | Volume 12 Issue 8, August 2023

Determination and Analysis of Height Differences between Orthometric and Ellipsoidal Heights for Engineering Applications

Selassie David Mayunga

Abstract: This study compares and analyses orthometric and ellipsoidal heights differences of points on the earth?s surface for engineering applications. Differential levelling was used to determine orthometric heights of 72 points and Global Positioning System (GPS) was used to determine three-dimension coordinates of the same points with a period of thirty (30) minutes at each GPS point. The reduced levels from differential levelling were computed using rise and fall method while the 3D coordinates determined using GPS was adjusted using Least Squares Solution software. The accuracy of the height differences was determined using standard deviations. The standard deviation of ellipsoidal height difference was 53.59cm while the standard deviation for orthometric height was 53.07cm respectively. A Root Mean Square Error value of 0.131m was obtained as the accuracy of the change between the two height differences while the correlation coefficients for the observations for differential levelling and GPS observations were 0.999 and 0.998 respectively. The result also indicated that there is a very small height difference between the two reference systems.

Keywords: Differential levelling, GPS, Ellipsoidal height, Orthometric height

Edition: Volume 12 Issue 8, August 2023,

Pages: 1653 - 1661