Determination of Transformation Parameters for Montserrado County, Republic of Liberia
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Date
2013-07-13
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Abstract
Spatial reference and geographic data integration has always been a crucial issue in positioning. To accomplish this, different referencing systems have been adopted by various countries for mapping and positioning purposes. This is due to the fact that no single ellipsoid could perfectly fit and model the undulating nature of the earth’s surface, establishing reasons why countries adopt local ellipsoids and datum. On the other hand, GPS equipment which is the most popular and dominantly used equipment for positioning is based on the WGS 84 ellipsoid/spheroid. Henceforth, data integration between local systems and the global system remains an issue of concern. As a case study, the Liberian Geodetic System which is based on the Clarke 1880 spheroid was used in the scope of this project. Various transformation models, reference figures and map projection procedures were studied and reviewed giving an insight of the nature of work to be done. Data were collected for common points in Liberia and post-processed both in Liberia and Ghana using the Leica GeoOffice and the Spectrum Survey. For the corresponding coordinates of the common points in the Clarke 1880 system, the 1:50,000 map which was provided by the Ministry of Lands, Mines and Energy was used spatially to extract those coordinates with the aid of ArcMap 10.0. Matlab functions were written to compute the parameters using four transformation models (Abridged Molodensky - 5 parameters, Simple Three Parameters - 3 parameters, Bursa Wolf – 7 parameters and Molodensky-Badekas – 7 parameters). Statistics were also performed on the determined parameters. As part of the objectives, another application was written using the Visual Basic programming language which makes use of these parameters to transform coordinates between the two systems. From statistics on the determined parameters and considering its advantages, the Molodensky-Badekas (Seven Parameters) Transformation Model is the most suitable model to be used to transform coordinates between both systems in the study area.
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A Thesis Submitted to the Department of Geomatic Engineering Kwame Nkrumah University of Science and Technology in Partial fulfillment of the requirements for the Degree of Master of Science Faculty of Civil and Geomatic Engineering College of Engineering.2013