Metadata standards
- ASEG-GDF2 (Pratt, 2003) is an ASCII data exchange and archive standard for geophysical point and line data. It defines the way in which data such as aeromagnetic, airborne EM, gravity and other point located data sets should be exchanged and archived. The primary objective of the standard is to provide a self-documenting and consistent method for exchanging and archiving of located geophysical data between organisations with different hardware and software systems.
Point and line data formats
- ASEG-GDF2 (Pratt, 2003) is an ASCII data exchange and archive standard for geophysical point and line data. The standard describes a self defining format that will allow located data to be automatically identified and loaded in a computer application. An ASEG-GDF2 data exchange has a minimum of four files. A decodable format description in the primary file separates the formatting details from the data. A second file contains a text description of the data and survey contents. The third file contains associated metadata with specification details for the map datum and projection for the geophysical data. The fourth file contains the geophysical data. The format description file defines information such as field names, units of measurement, format, comments and missing data substitution values (nulls). The data is contained in simple, multi-column ASCII files (tables).
- NetCDF-4/HDF5 (Ip et al., 2019) is a set of software libraries and self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data.
- GSPy (James et al., 2022) proposes a new Geophysical Standard (termed the GS convention) that leverages the well-established and widely used NetCDF file format and builds on the Climate and Forecasts (CF) metadata convention. The accompanying open-source Python package GSPy (Folks et al., 2022) provides methods and workflows for building the GS-standardized NetCDF files, importing and exporting between common data formats, preparing input files for geophysical inversion software, and visualizing data and inverted models. The current implementation supports both time and frequency domain electromagnetic data, raw and processed, 1-D inverted models along flight lines, and 2-D/3-D gridded layers.
Gridded data formats
- NetCDF-4/HDF5 (Ip et al., 2019) is a set of software libraries and self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data.
- Earth Resource (ER) Mapper: A vector image file format associated with the ER Mapper and ER Viewer products currently owned by Hexagon Geospatial. It consists of a text-based .erv file containing image attributes and metadata, and another file (usually with no extension) containing the image data.
- ESRI Shape Files with KML files of flight lines. An ESRI shapefile is a vector data storage format for storing the location, shape, and attributes of geographic features. It is stored as a set of related files and contains one feature class. Shapefiles often contain large features with a lot of associated data and historically have been used in GIS desktop applications such as ArcMap. The primary way to share shapefile data is via a .zip file that must contain at least the .shp, .shx, .dbf, and .prj files components of the shapefile. KML is a file format used to display geographic data in an Earth browser such as Google Earth.
References:
Foks, N.L., James, S. R., and Minsely, B. J. 2022. GSPy: Geophysical Data Standard in Python. U.S. Geological Survey software release. https://doi.org/10.5066/P9XNQVGQ
Ip, A., Turner, A., Poudjom-Djomani, Y., Brodie, R.C., Wynne, P., Druken, K., Symington, N. and Kemp, C., 2019. Discovering and using geophysical data in the 21st century. ASEG Extended Abstracts, 2019(1), pp.1-6. https://doi.org/10.1080/22020586.2019.12073191
James, S.R., Foks, N.L. and Minsley, B.J., 2022. GSPy: A new toolbox and data standard for Geophysical Datasets. Frontiers in Earth Science, 10, p.907614. https://doi.org/10.3389/feart.2022.907614
Pratt, D.A., 2003. The ASEG-GDF2 standard for point located data. ASEG Standards Committee, 33. Viewed 17 November 2022, https://www.aseg.org.au/sites/default/files/pdf/ASEG-GDF2-REV4.pdf