Software photogrammetry allows digital surface models to be generated from stereo pairs of photographs. In this case, 66 photographs at 1:20 000 were taken by the NERC Airborne Remote Sensing Facility (http://www.nerc.ac.uk/arsf/), and georeferenced using differential GPS. Photogrammetry produces a digital surface model, rather than a digital terrain model; careful choice of collection parameters can remove many of the unwanted features (trees and buildings, but not large areas of woodland etc.). The model can then be further edited if required. The photographs were then orthorectified (to remove lens distortion and relief displacement), and mosaicked together (Roughley and Shell 2001; 2002; forthcoming).
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Last updated: Thur Nov 11 2004