Contouring of geophysical and geochemical data using piecewise polynomials: application to airborne radiometric data

Contouring of aeroradiometric data in terms of uranium, and their ratios help in evaluating the uranium potential of a region and is one of the major objectives in uranium exploration programme. Several interpolation techniques in one or two dimensions are required to generate such data at unsampled locations before drawing the contours. These include linear, Hermite, Bessel, Akima, and non-linear splines namely, cubic, rational, exponential, weighted, and bi cubic or biharmonc interpolations. The problem of two-dimensional interpolation by use of piecewise bi cubic functions has been studied by many workers and are briefly discussed in this paper. These techniques can be applied to different types of geophysical and geochemical data collected underground, on ground or air. These techniques have been tested first on a sequence of airborne data and then applied to contouring for gridded data. The gridding of the irregularly spaced data along a zig-zag flight line is done by the inverse distance weighing scheme for reducing observed airborne radiometric data to regular grid. (author). 38 refs., 14 figs