There are many tasks in geosciences where geometry analysis is required to better understand a given phenomenon or process. Surface geometry analysis was originally developed in geoniorphology where geometrical properties of relief significantly influence geomorphological processes (e.g. water erosion, landslides, etc.). From the geometrical point of view, this analysis is 2-dimensional because 2 independent variables (x, y) are used. The phenomenon is modelled using a bivariate function z = f(x, y). However in geological applications, 3-dimensional cases are more obvious. Therefore, a trivariate function w = f(x, y, z) is used. The most important surface geometry analysis parameters expressed using partial derivatives of bivariate function z = f(x, y) are (Krcho 1990), (Mitasova & Hofierka 1992): slope, aspect, profile curvature, tangential curvature.