Michael D. Wilson, 1975. "Comparison of Fan-Pass Spatial Filtering and Polynomial Surface-Fitting Models for Numerical Map Analysis", Quantitative Studies in the Geological Sciences, E. H. Timothy Whitten
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A comparison is made of the conceptual and mathematical models of two numerical map analysis techniques, polynomial surface fitting and fan-pass spatial filtering. Fan-pass spatial filtering is designed to isolate trends with a specified orientation. In this respect it is complementary to polynomial surface fitting and band-pass spatial filtering, which delineate trends on the basis of size.
Spatial filtering techniques are superior to polynomial surface fitting because they more accurately preserve the position, orientation, length, width, and relative amplitude of local anomalies. However, two major disadvantages of most forms of spatial filtering are the requirement that the input data be gridded and the presence of edge effects in filter output. Gridding procedures may alter the input data in an undesirable manner by removing, reducing, or creating local anomalies or random noise. Edge effects, which are inherent products of the spatial filtering process, can be minimized in several ways. Development of spatial filtering techniques that utilize irregularly spaced data and establishment of accepted criteria for determining the quality of polynomial trend surfaces would improve the usefulness of both techniques.