2-D and 3-D Trend Analysis - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 268

Fig. 7.27 Part of two-dimensional power spectrum (a) and autocorrelation (b) functions for array
depicted in Fig. 7.26 . Note that largest values in a are concentrated in block around the origin,
suggesting a trend which may be described by harmonic trend surface of second degree. Autocor-
relation surface is elongated in the direction of the trend (Source: Agterberg 1974 , Fig. 76)
precise underground drill-holes that are more evenly spaced and sampled in more
detail as well, can be predicted from these 20 values. This problem is analogous to that
of constructing a topographical contour map of a mountain chain when only a few
elevations would be provided for interpolation. Polynomial trend surface analysis
applied to the 20 development values produces patterns that show no resemblance to