Relief effects on aerial photos geometric correction

Aerial photos are the best support to detect changes in the landscape over the time, particularly when associated with GIS based analyses. Since all metrics calculated on a landscape (from area coverage by vegetation classes to patches shape and size) are sensible to geometric distortions, the geometric correction of aerial photos is due to allow a realistic multi-temporal study. In this paper the mostly used methods of rectification were applied to aerial photos of different terrain types, with respect to their roughness (a flat area, a hilly area and a volcanic area), aiming to test residuals in x and y axes, under different conditions of terrain roughness. Polynomial functions confirmed their power in rectification process only in case of flat areas, with an increase of the error with more rugged terrains; on the contrary, orthorectification assured great results for all terrain types. q 2005 Elsevier Ltd. All rights reserved.