Geographic data and information processing for geomodeling
GemGIS is a Python-based, open-source geographic information processing library. It is capable of preprocessing spatial data such as vector data (shape files, geojson files, geopackages), raster data, data obtained from WMS services or XML/KML files. Preprocessed data can be stored in a dedicated Data Class to be passed to the geomodeling package GemPy in order to accelerate to model building process. Postprocessing of model results will allow export from GemPy to geoinformation systems such as QGIS and ArcGIS or to Google Earth for further use.
GemGIS uses the full functionality of GeoPandas, rasterio, OWSLib, Pandas, Shapely, PyVista and NumPy.
All provided maps and examples were taken from the books 'Interpretation of Geological Structures Through Maps: An Introductory Practical Manual' by D. Powell and "An Introduction to Geological Structures and Maps" by G.M. Bennison referenced at the bottom. Many code examples were developed as part of the Master Thesis of Alexander Jüstel as referenced below and will now be provided and improved for the use in GemGIS.
Due to rasterio, GemGIS must be used with python==3.8.5. It is recommended to create a new environment for the use of GemGIS and to use conda-forge to install packages like geopandas and rasterio.
conda install -c conda-forge geopandasconda install -c conda-forge rasteriopip install gemgis
The core of GemGIS is made of the GemPyData class (gemgis.py). Its attributes can directly be utilized by GemPy making it easier for users to load data. Methods of the GemPyData class allow users to directly set these attributes. Multiple other files contain functions to manipulate vector data, raster data, etc.:
gemgis.py- core file containing theGemPyDataclassvector.py- file containing functions to manipulate vector dataraster.py- file containing functions to manipulate raster datautils.py- file containing utility functions frequently used for the manipulation of vector/raster datawms.py- file containing methods to load WMS services as arrays/rastersvisualization.py- file containing functions to simplify plotting of spatial datapostprocessing.py- file containing functions to postprocess GemPy geo_model datanotebooks- folder containing tutorial notebooks explaining the features ofGemGISand example notebooks applying these features
Data stored as points, lines or polygons as shape-files, geopackages or geojson files can easily be imported into GemGIS GeoPandas GeoDataFrames. X and Y coordinates can then be extracted for these objects for direct use in GemPy. Digital elevation models can be interpolated if contour lines with height values are provided. If the loaded exceeds the desired modeling/working area extent, the data can be cropped.
Rasters (stored as arrays in Python) such as digital elevation models store height information. The height of interface points can be extracted from these rasters. In addition, if a raster represents a layer in the subsurface, orientation values can be sampled for use in GemPy. Orientations are calculated via the slope and aspect of the provided raster. It is also possible to resize rasters, clip rasters or save rasters as referenced geotiffs again.
Online services provide a wide range of possibilities to work with spatial data. Currently, it is possible to load data from WMS services into GemGIS. The functionality will be extended to WCS and WFS services in the future.
Besides extracting interface points from already existing digital data, GemGIS makes it easy to use the data digitized from georeferenced maps. This includes the extraction of interface points but also the calculation of orientations for the modeling with GemPy based on the gradient of isolines. In addition, it is possible to extract the real world coordinates from georeferenced cross sections to use this data for geological modeling with GemPy.
XML/KML Data export will be available in the future.
PyVista is the main 3D visualization package of GemPy. In order for new users to get used to the package, it is possible to plot the input data as a PyVista plot. This includes plotting depth maps of surfaces extracted from GemPy, plotting georeferenced cross sections of geological maps at their true position in space, plot boreholes and their respective lithology in 3D, plot a topographic map with height information in 3D and many more features to come.
GemGIS offers a wide range of utility tools. These includes
- Conversion of vector data into custom sections directly usable in
GemPy - Conversion of GeoDataFrames into Pandas DataFrames for
GemPy - Setting the extent and resolution for a
GemPymodel based on vector data and lists - Load and save QGIS style files (QML) for use as a color_dict in
GemPy - Calculate orientations based on strike lines
- Interpolate missing strike lines to calculate orientations
- Read CSV files as GeoDataFrames
- and many more to come
GemGIS also offers postprocessing methods to use data from the GemPy model. These include:
- Export of the geological map as a shape file
- Extract boreholes from
GemPymodels - Create depth maps of surfaces
- and many more to come
- Jüstel, A.: 3D Probabilistic Modeling and Data Analysis of the Aachen-Weisweiler Area: Implications for Deep Geothermal Energy Exploration, unpublished Master Thesis at RWTH Aachen University, 2020
- de la Varga, M., Schaaf, A., and Wellmann, F.: GemPy 1.0: open-source stochastic geological modeling and inversion, Geosci. Model Dev., 12, 1-32, https://doi.org/10.5194/gmd-12-1-2019, 2019
- Powell, D.: Interpretation of Geological Structures Through Maps: An Introductory Practical Manual, Longman, pp. 192, 1992
- Bennison, G.M.: An Introduction to Geological Structures and Maps, Hodder Education Publication, pp. 78, 1990