# GeoModeller

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**GeoModeller** (old names include 3DWEG, Geomodeller3D) is a methodology and associated software tool for 3D [geologic modelling](/source/Geologic_modelling) developed by [Bureau de Recherches Géologiques et Minières](/source/Bureau_de_Recherches_G%C3%A9ologiques_et_Mini%C3%A8res) and [Intrepid Geophysics](/source/Intrepid_Geophysics) over the last 20 years. The software is written using [Open CASCADE](/source/Open_CASCADE) in [C++](/source/C%2B%2B) for the engine (geometry, topology, viewers, data management, ...), [Java](/source/Java_(programming_language)) for the [GUI](/source/GUI) and data are stored in extensible mark-up language [XML](/source/XML). GeoModeller has started to revolutionise the working practices, data standards and products of a [geological survey](/source/Geological_survey) as a whole. The software takes into account all [structural geology](/source/Structural_geology) data such as dip, dip directions, strike, hingelines and axialtrace to build the geometry of geological units.

## Methodology

GeoModeller utilizes a Digital Terrain Model, surface geological linework, cross-sections, geophysical interpretation and drillhole [borehole](/source/Borehole) data to enable the geologist to construct cross sections, or 3D models. 3D [Geostatistical](/source/Geostatistics) interpolation (co-kriging) using all the data (location of interface, dip, direction, ...) produces a 3D [implicit function](/source/Implicit_function) representing a solid model. The model build may take in account if necessary a network of [geologic faults](/source/Geologic_faults). The model could be represented by [triangulated](/source/Triangulated) objects each corresponding to one of the geological units present. Geologists can draw the model in their sections to obtain a fence diagram. The geologist can use their knowledge to add information in the 3D space until he obtain a 'right' model.

## Inversion of the 3D model

In geological and mining or oil exploration applications, [seismic](/source/Seismic_wave) profiles as well as [gravity](/source/Gravitation) and [magnetic](/source/Magnetism) data are often available. Interpreted seismic cross-sections directly provide data that can be processed directly as geometric constraints for 3D modelling. On the other hand, gravity and magnetic data provide indirect constraints. Presently, a 3D geological model is considered as the initial state of a constrained [inverse](/source/Inverse_problem) modelling of this data. That inversion is based on an iterative method, which is applied to a discrete version of the domain under study. This inversion formulation allows separate inversion of either gravity or magnetic data or simultaneous inversion of both datasets and [tensor](/source/Tensor) components of [gravity](/source/Gravity) and [magnetic field](/source/Magnetic_field) . The final result is a probabilistic 3D geological model.

## References

- Lajaunie Ch., Courrioux G., Manuel L. (1997). Foliation fields and 3d cartography in geology: principles of a method based on potential interpolation. Mathematical Geology, 29, 571–584.
- Halbwachs Y., Courrioux G., Renaud X., Repusseau P. (1996). Topological and geometric characterization of fault networks using 3-dimensional generalized maps. Mathematical Geology, 28, 625–656. (Best paper award in Mathematical Geology, by the International Association for Mathematical Geology.)
- Bosch M., Guillen A., Ledru P. (2001). Lithologic tomography: an application to geophysical data from the Cadomian belt of northern Brittany, France, Tectonophysics, 331, 197–227.
- [other articles or PhD thesis](http://www.geomodeller.com/geo/index.php?lang=EN&menu=GMLibrary-articles) [Archived](https://web.archive.org/web/20070830133005/http://www.geomodeller.com/geo/index.php?lang=EN&menu=GMLibrary-articles) 2007-08-30 at the Wayback Machine
- McInerney, P., Guillen, A., Courrioux, G., Calcagno, P. and Lees, T. Building 3D Geological Models Directly from the Data ? A new approach applied to Broken Hill, Australia. [https://web.archive.org/web/20080718213311/http://www.geomodeller.com/ig/knowledgebase/special_topics/3DGM_BuildModelFromData.pdf](https://web.archive.org/web/20080718213311/http://www.geomodeller.com/ig/knowledgebase/special_topics/3DGM_BuildModelFromData.pdf)

## External links

- [GeoModeller homepage](http://www.geomodeller.com)
- [old web site with models in France](https://web.archive.org/web/20070404164826/http://3dweg.brgm.fr/)

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Adapted from the Wikipedia article [GeoModeller](https://en.wikipedia.org/wiki/GeoModeller) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/GeoModeller?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.