|Lines on a map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of isolines allows map readers to infer relative slope and estimate surface elevation at specific places. Isolines might be either traced on a visible three-dimensional model of the surface, as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from estimated surface elevations, as when a computer program threads contours through a network of observation points or area centroids (Davis, 1986, pp. 353-77). In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slopes, pits and peaks.Â (MM)
Reference Davis, J.C. 1986: Statistics and data analysis in geology, 2nd edn. New York: John Wiley and Sons.