Modeling the deflection of the vertical components in certain area, have always vital role whenever precise geodetic computation is needed. Therefore the objective of the current thesis was to draw accurate and precise maps of the two components of the deflection of the vertical from the computed values of the same, by the least-squares collocation technique ( LSC ), at a grid of 5'x5' over the whole territory of Egypt, based on all the old and the recent available heterogeneous geodetic data related to the gravity field in the considered area.
Before appling the computational technique i.e, ( LSC ) to the available data, which are refered to different datums, these data where reduced to one and the same datum, the reduction was done by using several groupes of transformation parameters beetween the datum of a specific collection of data and the unifed datum (WGS84). The reduced rough data were filtered and then subjected to a process of smoothness before the predection step. The well-known remove-restore technique was used for achiving the maximum smoothness of the data, by the aid of an appropriate high degree global harmonic model, tailored to the local Egyptian terrestrial data. A digital terrain model of Egypt was also used for the same purpose. The final results have shown a rather accurate and precise maps of both predicted components of the deflection of the vertical over the intire territory of Egypt (22°N≤φ≤32°N; 25°E≤λ≤36°E). |
