Geospatial data is data specific to objects or phenomena that are directly or indirectly associated with a location relative to the Earth.
Location information for geospatial data can be represented by numerical coordinates together with the relative coordinate reference system, datum and temporal information (to account for tectonic motion). Geospatial information is often collected inadvertently, such as by digital cameras or GPS trackers on equipment, and can be very useful for locational meta-analysis of data collected for different reasons and by different disciplines. The power of a geospatial ‘tag’ on any data lies in its ability to make connections to other research modes, types and even to seemingly unrelated things.
Why is metadata for geospatial data so useful?
Despite the growing volume of geospatial data available from a variety of sources and the ease of identifying this data, discovery and use of this data still remains a challenge for researchers because of limited metadata. Metadata describes the data: it may be within the data structure itself; or it may exist separately and be associated with the data.
Where data pertaining to an entity on Earth does not already contain geographic location information, metadata containing the geographic location information for that data can be constructed and either included within, or associated with, the data – consequently improving wider discovery and use.
Detailed metadata is required to provide information about the data’s location, provenance, custodianship, as well as a clear understanding about the copyright and reuse conditions, all of which engender confidence in the research outputs and evaluate the potential reusability of the data.
The inclusion of metadata to enable the transfer or sharing of data is now a standard practice in the spatial communities, satisfying the FAIR data principles: Findable, Accessible, Interoperable, and Reusable. Metadata can ensure that users of geospatial data are aware of its geographic information, limitations, restrictions and of its suitability for use in their research.
Geospatial data formats
Geospatial data can be stored and exchanged in various ways:
- tabular data – e.g. csv or xlsx
- database (geo-specific or general)
- raster image – data represented as a grid of pixels with associated geographic information (JPG, GIR, PNH, TIF, PMP, PSD)
- vector image (AI, CRD or SVG )
- shapefile – non-topological format containing location and geographic entity metadata
- coverage – a georelational data model that stores vector data consisting of location information and other geographic entity metadata (SHP SHX and DBF)
- OpenStreetMap OSM XML
- Digital Line Graph (DLG)
- OGC® GeoPackage Encoding Standard
Specialised software applications, such as GIS software, can be used to access, manipulate, visualise and analyse geospatial data of varying formats.
Geospatial metadata standards
The international metadata standard ISO19115 has been widely adopted for describing geographic information and services. It has been adopted for use within Australia and is the basis for the ANZLIC metadata profile.
ANZLIC – the Spatial Information Council is the peak intergovernmental organisation that provides leadership in the collection, management and use of spatial information in Australia and New Zealand.
The ANZLIC metadata profile was developed to facilitate interoperability within and between Australian and New Zealand agencies and jurisdictions and is a profile of the AS/NZS ISO 19115:2005 (an identical adoption of ISO 19115:2003).
“ISO 19115:2003 defines the schema required for describing geographic information and services. It provides information about the identification, the extent, the quality, the spatial and temporal schema, spatial reference, and distribution of digital geographic data.” https://www.iso.org/standard/26020.html
The ANZLIC metadata profile differs from AS/NZS ISO 19115:2005 only in that it has a mandatory metadata identifier.
The ISO 19115:2003 has since been revised by ISO 19115-1:2014 and adopted identically as AS/NZS ISO 19115.1:2015. A best practice guide for its use is currently being developed within the The Intergovernmental Committee on Surveying and Mapping (ICSM).
Where can I find out more about Geospatial data and metadata in action?
Development of knowledge and skills relevant for the publication and use of geospatial data, can be assisted by participation in relevant communities of practice, such as:
- Geospatial Capabilities Community of Practice
- Australian Vocabulary Special Interest Group (AVSIG)
We’ve put together a list of handy resources and tools to help you ensure you’re always up to date on best practices for geospatial data and metadata:
- The GDA Modernisation Implementation Working Group (GMIWG) oversee the implementation of Geocentric Datum of Australia 2020.
- The Open Geospatial Consortium
- The Intergovernmental Committee on Surveying and Mapping (ICSM)
- The ANZ Metadata Working Group (MDWG) is a sub-committee of ICSM
- Permanent Committee on Geodesy which is responsible for managing the Australian Geospatial Reference System
- ANSLIC Committee on Survey and Mapping - basics of Datums