An open-source toolbox for 3D geological modelling in QGIS

3D modeling is a major asset for the understanding and quantitative characterization of subsurface geology. Geological survey organizations have produced 3D models for decades and are nowadays facing new kinds of demands for increasingly complex accurate representations of the subsurface. New challenges include "usual" difficulties such as integrating large sources of heterogeneous data, handling a wide range of possible model scales (from urban to national), but also new requirements on model uses. As an example, models should be easily (if not automatically) updatable and computable on various environments (not only in desktop software, but also in web / platform environments), models should also serve for multiple purposes and applications (which requires generating various kinds of representations of a single model), etc. 

In this talk, we present the toolbox we have been developing at the French Geological Survey over the last years to progressively replace our two historical and homemade solutions for 3D geological modeling (GDM and GeoModeller software). The toolbox contains two parts. The first one is a set of python and C++ libraries that provide data structures and computational capabilities. These libraries can run on a wide range of software environments. The second one is a set of QGIS plugins. They provide access to 3D modelling capabilities to the geologists directly in the GIS environment without requiring them to have development skills.

Throughout the presentation, we illustrate how the different design choices we made helped us achieve our main objectives: extensibility of the toolbox capacities, reusability of the software components and performance. One of the key features to achieve these objectives is the design of modular and open software components. It enables models and workflows to be easily adapted to fit a wide range of production needs. The integration into the open-source ecosystem also provides numerous benefits, and we illustrate how we had to support the development of core QGIS functionalities to better manage 3D geological objects.