Wykorzystanie metod interpolacji do numerycznego kreślenia map powierzchni geologicznych na podstawie nieregularnie rozmieszczonych danych

Abstract

Applications of numeric interpolation methods to the geological surface mapping using irregularly spaced data.Summary. In this paper we report a test of usage of interpolation methods available in Surfer 7.0 for interpolating irregularly distributed data. The experiment involved data of the top surface of glacial tills in the center of Wrocław. This surface is represented by 136 not evenly distributed data. Some methods are not useful for working with data on geological structures, as they produce maps that are highly unclear or unrealistic. Two parameters were used for describing usefulness of selected gridding methods: a sum of residuals to a power (2) and an overall look of a map. Firstly, five methods were tested on specially limited testing area with relatively dense data. Analysis of above mentioned parameters the afore mentioned parameters led us to choose the three following methods as producing clear maps with small 2: minimum curvature, modified Shepard’s method and kriging. Those methods, together with their special, previously optimized, parameters were applied for mapping the whole investigated area. The results showed that both minimum curvature and kriging produce maps of similar appearance and comparable 2. According to Davis (1986) and the software user’s guide kriging is good for small data sets (like our 136 points) while minimum curvature is useful rather for bigger data sets with more than 1000 points.