3D models

As part of its research activities and contracted projects, the Czech Geological Survey (CGS) is engaged in the construction of 3D geological models and in developing a uniform systematic approach to their design, archiving and presentation.

As the administrator of extensive geoscientific datasets from the entire territory of the Czech Republic, the CGS is involved in a number of applied research projects dealing with various ways of using the rock environment beneath the Earth's surface. Currently addressed issues of national importance, for which the 3D geological models are created, include high-speed railway tunnels, nuclear power plants, groundwater resources, mineral resources, geothermal energy potential assessment and, last but not least, the location of a deep high-level radioactive waste repository.

Map overview of 3D models

The CGS creates three types of models - medium- to large-scale structural geological models of the bedrock, photogrammetric models of relatively smaller-scale field localities, and photogrammetric models of collection samples. The interactive map below shows the areas of the Czech Republic for which structural geological or photogrammetric models of field localities have already been created. By clicking on relevant areas, users can view basic data about the models (metadata) and model previews (unless their public presentation is restricted). The map overview is continuously updated.

The 3DGM metadata profile, which is fully compatible with the requirements of the INSPIRE directive and with the international standard ISO 19115, was defined for a uniform metadata description of 3D geological models.

Structural geological models

The lack, heterogeneity and complexity of available archival and newly acquired geological data, as well as the complexity of the geological structure, often do not enable the use of (semi-)automatic geological modelling methods. Models must usually be constructed manually given the complex conditions of the Bohemian Massif. The 3D geological models (see examples below) created by the CGS cover a wide range of scales and lithotectonic environments. They range from metres as in the case of the outcrop quantification for fracture network models to regional scales covering areas of hundreds of square kilometres down to depths of around 1.5 km. They represent structurally complex highly metamorphosed units that have undergone several stages of ductile deformation, partial melting and intrusion of magmatic bodies, as well as relatively simpler overlying sedimentary formations. An integral part of the model construction also includes assessments of their credibility, which are mainly used for safety analysis.

Based on our 3D geological models, 3D hydraulic and transport numerical simulations are performed to estimate groundwater flow. The models are also used by design companies in CAD software as natural constraints for the technical design of underground buildings. A novelty is the export of the CGS geological models to the BIM SW environment, where they are integrated into the designs of future large-scale above-ground and underground constructions.

Sedimentary basins are modelled to explore for new energy sources and to find ways of reducing greenhouse gas emissions into the atmosphere. These topics require a new 3D view of geological structures, their geothermal, raw material and storage potential. Processing large-scale geophysical and geological datasets using new 3D modelling programmes provides the possibility of spatially depicting the architecture of sedimentary basin infill with lithological, sequence-stratigraphic details and faults. 3D models are used to evaluate geological units in terms of the extent and quality of aquifers / reservoirs, sealing layers (see image below), testing of planned technological procedures and associated environmental hazards.

Currently, the CGS uses MOVE software for constructing structural geological models and also Petrel software for modelling basin areas. Publicly available visualization of 3D models is presented in the form of a 3D web scene, which is stored in the ArcGIS Online environment. The scene can be viewed using the standard viewer integrated in this environment.

Photogrammetric models of field localities

In addition to 3D structural geological modelling, which deals with the subsurface rock environment, the CGS is also developing a methodology for creating surface 3D photogrammetric models. This activity closely involves the use of drones in CGS activities and the related need to process and visualize the data captured by them. Surface photogrammetric models can also be created based on manual photographs, taken during the documentation of a quarry or mine. In the future, these models will also be constructed for some protected geological localities.

Agisoft Metashape software is used to create the photogrammetric models from captured images by creating point clouds and three-dimensional objects with orthomosaics, located in a geographic coordinate system. The software also allows for working with multi-band spectral (multispectral) images, which are used for scientific study of monitored surfaces. A custom solution developed by the CGS, based on the open-source javascript library Three.js, is used to display these models online.

Photogrammetric models are used, for example, to monitor rockfalls at the Nechranice Water Reservoir, to monitor and study historical mining on the Jizerka Stream, or to reconstruct underground mine spaces.

Photogrammetric models of samples from the CGS collections

For scientific and popularization purposes, the CGS employs photogrammetry to gradually publish models of some noteworthy specimens from its paleontological and mineralogical collections. The models are created using a uniform methodology. In addition to popularization, they are also used for scientific collaboration with foreign colleagues.

Models of selected parts of the plesiosaurid skeleton

Web visualization of  photogrammetric 3D models of skeletal fragments of a marine reptile of the family Elasmosauridae; Vega Island - Antarctica; Upper Cretaceous; Snow Hill Island Formation.

The models shown on the website are very data-intensive (one model roughly 100-200 MB) and require sufficient graphics card performance on your device (but they should also work on modern mobile phones and tablets). Please send all comments and observations regarding the visualization of samples to webmaster@geology.cz.