Abstract: Contouring Geologic Data from Arbitrary Points

D. R. McDonald, C. J. R. Braithwaite, A. Jawad Ali

The analysis of distribution of numerical values of properties of geologic and biologic samples commonly is made difficult by an arbitrary distribution of data points. Logistic problems such as the nature of the terrain may prevent the imposition of a predetermined sample grid, or statistical procedures may require a deliberate selection of random samples.

Values at points on a regular grid may be interpolated from original values at arbitrary points, using a distance-weighted least-squares-approximation technique. Contours then may be drawn using values on the regular grid. Contouring accuracy and smoothness are dependent on the coarseness of the grid, as only linear interpolation is used and straight-line segments are drawn between appropriate points on the grid for a given contour.