“…However, the identification and quality of ground control in archival photography is often problematic. As a result, much research has been carried out in order to reduce the need for these costly and difficult to measure GCPs by means of surface matching (see, for example, Li et al, 2001;Mills et al, 2003Mills et al, , 2005Miller et al, 2008;Akca, 2010;Aguilar et al, 2012), or extracting GCPs from lidar-derived digital elevation models (DEMs) (James et al, 2006). Nowadays the results regarding the application of self-calibration to archival photography are extremely variable.…”