Specific geomorphometry is the measurement and analysis of specific surface features defined by one or more processes, and separated from adjacent parts of the land surface according to clear criteria of delimitation (Evans 1974, p. 386). This section is concerned not with description of individual landform features, but with landforms that are distributed regionally as a set of replicates. It is assumed that all individuals are geocoded by coordinate pairs and that the sample replicates required for statistical analysis are compatible in data quality. Most measurements used for analysis of shape and pattern in specific geomorphometry are ultimately drawn from a map source. The map may be compiled from an original field survey or from secondary sources such as air photographs, published topographic maps, or satellite imagery (Ford 1984). The optimal way to analyse map data is with an automatic digitiser, and numerous computer programs are now available to process digitised data (Marble et al. 1978). The range of phenomena to which specific geomorphometry has been applied is considerable, and now encompasses investigation of an interplanetary nature (Table 2.3).