Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Rectangular 'Satlevel' Model for Quick Determination of Geoid: A Case Study of Lagos State of Nigeria
by Olaleye, J. B. Badejo, O. T. Olusina J. O1 and Aleem, K. F.

Abstract:
There are several approaches to geoid modelling such as the use of stokes's formula, astro-geodetic, astro-gravimetric, GPS/Levelling and 'Satlevel' collocation models. 'Satlevel' is a new method of geoid determination, in which the ellipsoidal height is used along with Orthometric Height to model the geoid. Geoid modelling is a process of developing mathematical algorithms to represent the geoid. New Rectangular 'Satlevel' adopts space rectangular coordinates in 'satlevel' method. This reduces the time, cost and energy in geoid determination - a key problems in geodesy. Geoid can be determined within a survey area when available ellipsoidal height can be compared with Orthometric Height. In this work, ellipsoidal and Orthometric Heights along with other data were extracted from comprehensive mapping of Lagos GIS enterprise. Polynomial model using least squares method was developed from the combination of Orthometric and ellipsoidal heights along with space rectangular coordinates to derive the Geoidal Coefficients. The Geoidal Coefficients were used to get the geoidal undulation of the study area. Statistical tests and goodness of fit analysis were carried out. The model was also validated using some of the acquired data that were not used for the development of the model. Furthermore, statistical analyses show that there is no significant difference between the values obtained with the derived model and observed values. The Rectangular 'Satlevel model provides a quick determination of geoid in Lagos State and can be adopted for other part of the country and elsewhere.

Keywords: Geoid, modelling, ellipsoidal height, orthometric height, 'satlevel'

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