Visualization for 3D Information in Earth Science using GOCAD
Résumé
Extensive work has been done in the area of 3D Visualization and modeling using CAD approach [1]. These methods can be selected it into two categories: namely, CAD objects and natural objects. CAD technology requires the topology of objects at the conception and collaboration stages. It mainly concerns manufactured or industrial objects. Triangles or tetrahedral elements are used to fit the surface or the volume of the final object using spline or Bezier interpolation methods. Several industrial CAD systems are based on such a concept and are widely used in the industry among the most popular ones Auto-CAD, Strim 100. As natural objects are usually investigated from irregular sampling points (bore hole, sections, points), the topology of the underlying real object is not known. This uncertainty as to real shape implies that the classical CAD approach might be irrelevant, as shown by several pioneer works [2]. In fields such as geology or environmental sciences, it frequently need to reconstruct the underlying structure from indirect information or from scarce, irregular, or partial data points. The situation can be further complicated by the presence of discontinuities such faults, fractures or folded layers, holes or non manifold surfaces where the B-spline approach is irrelevant. This is why the natural object approach has been developed specifically to handle complex natural 3D objects. It involves specific data structures and objects oriented program in which will be shortly presented.