Abstract
Shiono et al. (2001) proposed an algorithm to determine an optimal geologic boundary surface based on exterior penalty function method, using the surface expressed in the form of DEM (Digital Elevation Model). This algorithm has an advantage that inequality data and strike-dip data are available. However, it has also disadvantages that the optimal surface must be saved as DEM, that an approximation error occurs in calculation and that it is hard to generate DEM with a large size of grids. To solve these problems, a new algorithm was developed based on Inoue (1985, 1986)'s ideas by applying a bi-cubic B-spline function to Shiono et al. (2001)'s algorithm, and was coded in a Fortran program BS-Horizon. This enables us to determine the optimal geologic boundary surface without approximate calculation, to save it as a mathematical function, and to generate DEM with a large size of grids such as high resolution DEM or wide-area DEM.
