A Dot Matrix Method of Portraying Continuous Statistical Surfaces
Richard E. Groop, Paul Smith · The American Cartographer · 1982
Smooth statistical surfaces are conventionally represented by isoline maps or block diagrams. Perceptual studies have suggested that these illustrations are difficult for map readers to interpret and that overall surface configuration is particularly elusive on isoline maps. This paper presents an alternative method of illustrating continuous surfaces. The technique employs a digital plotter to create finely-spaced point symbols that vary in size according to interpolated z-values. Symbol sizes are scaled such that percent area inked is proportional to surface value. After photographic reduction, the map has the appearance of a continuous change in gray tone corresponditlg to the surface it represents.