Abstract: A signal processing mechanism for interpolating elevation data values between successive data points of a terrain map from which a simulated radar return image may be produced employs a signal processing operator in accordance with which input data signals representative of the elevations at successive data points on the terrain map are processed, to derive a continuous interpolated (terrain map) functional characteristic. Interpolated elevation data values at one or more points between successive ones of the original data points are calculated by employing elevation values for successive data points adjacent to those data points between which the one or more additional points of interest are located.