1. a Civil Engineering Department , Polytechnic Institute of Leiria, Edificio Sede, R. General Norton de Matos , Portugal
2. b Institute for Systems and Computers Engineering at Coimbra , Portugal
3. c Department of Mathematics , University of Coimbra , Rua Silvio Lima, 3030-790, Coimbra, Portugal
4. d ISISE, Civil Engineering Department , University of Coimbra , Coimbra, Portugal
5. e Portuguese Geographic Institute (IGP), Remote Sensing Unit (RSU) , Rua Artilharia Um, 107, 1099-052, Lisboa, Portugal
6. f CEGI, Instituto Superior de Estatística e Gestão de Informação, ISEGI, Universidade Nova de Lisboa , Lisboa, 1070-312, Portugal