1. Lecturer Professor, Area of Cartographic Engineering, Geodesy and Photogrammetry, Univ. de Extremadura, Sta Teresa de Jornet, 38, Mérida 06800, Spain.
2. Lecturer Professor, Dept. of Mathematics, Univ. de Extremadura, Sta Teresa de Jornet, 38, Mérida 06800, Spain (corresponding author).
3. Ph.D. Student, Area of Cartographic Engineering Geodesy and Photogrammetry, Univ. de Extremadura, Sta Teresa de Jornet, 38, Mérida 06800, Spain.