Non-homogeneous solid modeling with octrees. A geological application

From an historical point of view, geometric modeling techniques usually represent the surface of solids. However, the increasing development of new fields in CAD applications like molecular systems, medicine, or geology, requires the codification of both surface and volume information in the model. Possible extensions of classical modeling methods for volume codification have been analyzed: Boundary Representations, Constructive Solid Geometry (CSG), and Octrees. Our solution focuses on octree representations, since its inherent spatial division supports handling and representation of volume properties. This paper describes different specifications of octree models, depending on the type of surface and volume data. A geological implementation is then presented, and its specific octree model is justified.