National Center for Geographic Information and Analysis

This unit is the first of two that focuses on spatial interpolation—the procedure of estimating the value of properties at unsampled sites within the area covered by existing observations. It discusses several different methods for classifying spatial interpolation procedures, such as point vs. areal, global vs. local, and exact vs. approximate. Several point-based methods are described, both exact—proximal, B-splines, Kriging and manual (“eyeballing”)—and approximate—trend surface analysis, Fourier series and moving average/distance weighted average.