Terramod-BS : Visual Basic Program for Determination and Visualization of Geologic Boundary Surface Including BS-Horizon Module

We have developed a series of Visual Basic Program Terramod for modeling and visualizing of geologic surfaces based on irregularly distributed field observation including equality-inequality elevation data and strike-dip data. The current version applies an algorithm of Horizon2000 (Shiono et al., 2001) to determine the optimal surfaces, in which the surface is approximated by a set of values at grid points. This version has the same disadvantages as Horizon2000; it is hard to generate quickly a large sized DEM. We revised the program by applying an algorithm of BS-Horizon (Nonogaki et al., 2008) instead of Horizon2000. As the surface is processed in a form of a bi-cubic B-spline function, we can generate easily a high resolution DEM over a wide area under Windows environment. This paper describes how to use the