1. Department of Physics, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon
2. Geodesy Research Laboratory, National Institute of Cartography, Yaoundé P.O. Box 157, Cameroon
3. Department of Civil-Engineer, University of Ngaoundéré, Ngaoundéré P.O. Box 455, Cameroon
4. Department of Mathematical Economics and Econometrics, Omar Bongo University, Libreville P.O. Box 13113, Gabon
5. Laboratory of Image Processing, National Institute of Cartography, Yaoundé P.O. Box 157, Cameroon