Chapter 41 The Display of Digital Soil Data, 1976–2004

Abstract The aim of this chapter is to explore the relations between the perception and observation of soil in the field and the methods used for displaying the information gathered. The main hypothesis is that our insights into the spatial and temporal variation of soil over the landscape are to a large extent controlled by the conceptual models available to us. This range of conceptual models is, in turn, controlled by the methods of display at our disposal, which increasingly make use of digital graphics. The chapter adopts a historical approach, arguing that developments in the visualisation of soil and other geographical, statistical and cartographic data reflect our understanding of the formation and behaviour of soil in the field. The first digital soil data were merely electronic versions of paper maps and profile descriptions that adopted an exact object approach. Developments in interpolation, especially kriging, use an alternative conceptual model, namely that of the continuous smooth surface, which has been further modified to include notions of noise and short-range variation. Further developments in cokriging have enabled the integration of extra data to improve the interpolation, in particular using data on surface elevation and slope. The value of elevation data for enhancing understanding soil–landscape relations through improved visualisation was first demonstrated by 3D “draping” of both conventional and interpolated maps of soil data over digital elevation models (DEMs). Further developments in the visualisation of soil types have made direct use of derivatives of DEMs such as slope, elevation, rates of curvature, directly received solar radiation in order to both classify and map soil automatically. The current state-of-the art is the use of 3D in addition to time models of soil formation and distribution that reflect changes in soil patterns over time. The results of these models require computer graphics for adequate display and interaction.