Analogue (e.g. Finster-walder, 1954), analytical (e.g. Reinhardt and Rentsch, 1986;Etzelm¨ uller and others, 1993) and digital (e.g. Baltsavias and others, 2001; Keutterling and Thomas, 2006) photo-grammetry has provided valuable tools for mapping previ-ously inaccessible areas, and, despite considerable advances in satellite remote-sensing technologies, aerial photographs can still provide the highest spatial resolution datasets