ABSTRACT
Major objectives of geomorphologic inquiries are the characterisation and explanation of earth surface processes as they vary over time and space. This chapter outlines methods of measuring heights and horizontal lengths or distances from photographs taken on the ground with hand-held cameras. Photographs of a particular geomorphic setting taken several decades ago show scenes and yield dimensions of landforms which differ from those of the present day. The variety and obscurity of sources for historical geomorphology photography brings about a convergence of the interests of the geomorphologist, the historian and the detective. As with most specialties, photogrammetry (the process of making quantitative measurements from photograph-like images) has a set of specialised terms. The chapter also presents a detailed discussion on the follwoing concepts: focal length, depression angle, principal point, x-axis, y-axis, true horizon, and vanishing-point.
