Geological 3D/4D Modelling

Modelling geological structures and history always starts with a careful geometric analysis of the present assembly of geological surfaces, bodies and property distributions, this being the key to reveal the nature and interaction of earlier processes.

A process of computer-aided development of a consistent geometric model is known in geology as interactive 3D/4D modelling. The model built in the process of interactive modelling is further checked by backward restoration and balancing. The final model is used for the specification of boundary conditions for 3D transport models, or for the production and consistent updates of geological maps.

Geological strata are sheet-like structures in earth with different mineral composition, texture and/or grain size. A stratum is modelled as a volume (or a set of volumes) usually specified by its bounding surfaces.

A fracture in earth materials along which the opposite sides have been displaced is known as a fault. A fault is used to be modeled as a surface.

A cross-section is a geological abstraction obtained as a result of an intersection of a vertical plane with geological strata and faults.

The starting point for the interactive geological 3D/4D-modelling is a digitalization of geological cross-sections.	The second step in the interactive 3D-modelling is the generation of triangulated surfaces from the point sets spread between two sections.	The final step is the transition from stratigraphical bounding surfaces to volumes .

Figures (C) GOCAD