Effect of Latitude As a Significant Element on the Results of Direct UTM Coordinates Transformation Method

The transformation of global navigation satellite systems coordi- nates between any two datums represents a vital procedure. Although the geocentric coordinates (X, Y, Z) of two datums can be trans- formed using the 7-parameters method, the conversion of Universal Transverse Mercator (UTM) projected coordinates (E, N) between two systems cannot be applied with the same procedure. However, see Jassim (2022), which discusses a method that allows the transformation between any two datums using the utm projected coordinates directly regarding the variation of the datum's semi-major axis and the eccentricity. The results of the evaluation of this method show that there is a significant shift in the transformed coordinates due to the imperfection of the used algorithm. While this research suggests a modification in the previous algorithm by adding the latitude's variation as a third significant factor besides the other two variations (∂a, ∂e2, and Δ), the suggested modification gives a high decline in the uncertainty of the position values. Furthermore, it takes a homogenous fixed limit for different places over Iraqi territory.