Definition
Geospatial information 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).
Foundation Spatial Data Indexing (FSDI) framework
Spatially enabling business data means applying (preferably standard) location or spatial indexes with the core being parcel identifier, property identifier, address and spatial coordinates (x, y, z). These core spatial indexes underpin a range of authoritative administrative boundary indexes – localities, local government areas, electorates and the Australian Statistical Geographical Classification (ASGC).
The Australian Statistical Geography Standard (ASGS) is the common boundary set for analysis, display and reporting of socio-economic information within the Statistical Spatial Framework for Australia. The ASGS boundaries were developed by the ABS to reflect the location of people and communities, and used for the release and analysis of statistics and other data.
- The ASGS is updated every 5 years to account for growth and change in Australia's population, economy and infrastructure.
Statistical Geography allows users to understand, compare and analyse statistical data for informed decision making about all sorts of places from cities and suburbs to regional areas or Local Government Areas. The Statistical Spatial Framework is designed to help data custodians to add location to their datasets and enable users to integrate geospatial and statistical information.
NSW uses a standard for reporting a minimum set of metadata elements based on the Australian New Zealand Land Information Council (ANZLIC) and International Organisation for Standardisation (ISO) 19115 profiles.
The NSW Spatial Metadata Policy (2010) recommends all State Government agencies and Local Government authorities provide metadata for corporately significant spatial data produced, enhanced or exchanged between agencies and made publicly accessible via the NSW Spatial Data Catalogue (www.sdi.nsw.gov.au).
The NSW Spatial Data Catalogue uses an ISO 19139 compliant XML (Extensible Mark-up Language) Metadata Statement that is uploaded to the catalogue.
| Minimum elements for metadata in NSW | Description |
| Title | The name of the data layer. |
| Abstract | Similar to an executive summary. |
| Purpose | Why the data was created and what it was meant to achieve. |
| Metadata contact organisation | Organisation contact details for the metadata content. |
| Geographic location – coordinates | The spatial extent of the data: east / west longitude. North / south latitude. |
| Lineage | From what other data was this data constructed and the methods used to create the dataset? |
| Temporal extent | Over what period was the data captured? |
| Distribution format | The data file format, web map service, etc: • Name • Version |
| Keywords | Words that can be used in a search to find the metadata record |
| Maintenance frequency | How often is the data updated or maintained? |
| Use limitation | What are the constraints and limitations on how the data can be used? |
| Legal restrictions | Copyright and intellectual property permissions: access and/or use. |
Description
Point
XY: The XY refers to longitude (X) and latitude (Y) which may or may not include height information at a particular epoch and is associated with textual based information. Agencies collecting and/or assigning geocodes should ensure wherever possible that the correct datum and projection as described above are used. The use of a consistent datum and projection ensures interoperability of information in a variety of geographic information systems (GIS).
Note that users of latitude and longitude metadata may have different requirements. Therefore in addition to the latitude and longitude data elements using the decimal degrees representation, (based on the AS 4590 standard) two additional data elements have been created. These items use the traditional degrees, minutes and seconds representation, and are based on the AS 6709:2008 Standard representation of latitude, longitude and altitude for geographic point locations standard.
Address String An ‘address’ compromises the core components road number, street name, street type, suburb, etc. Together, these components are known as an ‘address string’. Most commonly government information may be associated with an address where the XY may be derived from the address string. The address information recorded by NSW Government agencies may include all or some of the address components listed above and those contained in Figure 2. NSW Government agencies collecting address string information should check the validity of the information against NSW Point. Note: Australia Post is an authoritative source for postal addresses but not for physical address strings.
Line
Road Segment: The road segment information recorded by agencies may include primary attributes such as road name (e.g. where the full address is unavailable). Recording of this information should be undertaken using the ‘road segment’ dataset available from the NSW Digital Topographic Database (DTDB), held and maintained by DFSI Spatial Services. This dataset is a foundation spatial dataset as defined by the NSW Foundation Spatial Data Framework (FSDF). The NSW FSDF represents the single source of truth and authoritative spatial datasets in NSW.
Polygon (Area)
Locality: The locality information recorded by agencies should conform to the ‘suburb’ dataset available from Spatial Services’ NSW Digital Cadastral Database (DCDB). The Suburb dataset is a foundation spatial dataset as defined by the NSW FSDF.
Postcode: Australian postcodes are managed by Australia Post for the exclusive purpose of assisting in delivery mail to its customers. To that end Australia Post only allows its postcodes to be used as a “non-commercial” reference. Postcodes also change continually, and bear little relationship to other official geographies such as State borders and Local Government Areas. For these reasons, their use as a determinant of location for NSW Government service delivery is inappropriate.
Local Government Area: The Local Government Area is an administrative boundary containing a number of localities or suburbs. In the course of recording information that involves the collection of local government areas, NSW Government agencies should use the ‘local government area’ dataset contained within the NSW DCDB for verification. The Local Government Area dataset is a dataset defined by the NSW FSDF. Local Government Area is the only administrative boundary specified in this standard. For some processes or transactions it may also be useful to record data about other types of administrative boundaries. In such cases, agencies should refer to the relevant industry standard or contact Spatial Services for further information.
ABS Structures
The ABS Structures include several different geographies that approximate urban areas, and these may differ from official or commonly accepted definitions.
- Mesh Block: Mesh Block data is sourced from the Australian Bureau of Statistics (ABS) and is part of their Australian Statistical Geography Standard (ASGS). Mesh Blocks are the smallest geographic areas defined by the ABS and form the building blocks for the larger regions of the ASGS. Most Mesh Blocks contain 30 to 60 dwellings.
- Statistical Areas Level 1 (SA1s) are designed to maximise the geographic detail available for Census of Population and Housing data while maintaining confidentiality. Most SA1s have a population of between 200 to 800 people.
- Statistical Areas Level 2 (SA2s) are medium-sized general purpose areas built to represent communities that interact together socially and economically. Most SA2s have a population range of 3,000 to 25,000 people.
- Statistical Areas Level 3 (SA3s) are designed for the output of regional data and most have populations between 30,000 and 130,000 people.
- Statistical Areas Level 4 (SA4s) are designed for the output of a variety of regional data, and represent labour markets and the functional area of Australian capital cities. Most SA4s have a population of over 100,000 people.
Comments
The addressing information interchange section of AS 4590 has been aligned with AS/NZS 4819, Geographic information—Rural and urban addressing. AS/NZS 4819 was compiled to direct authorities required to allocate physical addresses, whether they be to properties, features or facilities. This revision of AS 4590 has been extended to cater for new address provisions noted in AS/NZS 4819 and has been reviewed and amended to minimise ambiguity and maximise understanding in client data interchange.
Datum
From 1 January 2020, GDA2020 is the legal datum for NSW supported by amendments to the Surveying and Spatial Information Act 2002 (NSW) and Regulation 2017 (NSW) (S&SI Act and Regulation).
- GDA2020 is of higher accuracy than GDA94, aligns more closely with GPS and GNSS positioning services and supports nationally consistent datasets, free of the known distortions of GDA94. In NSW, GDA2020 coordinates are approximately 1.5 metres to the north-east of GDA94 coordinates, which represents the motion of the Australian tectonic plate between 1994 and 2020.
For ASGS Edition 3 (2021), digital boundaries are available in both the Geocentric Datum of Australia 2020 (GDA2020) and the Geocentric Datum of Australia 1994 (GDA94). GDA2020 was adopted as the new official national datum in 2017 and will be adopted gradually by organisations across Australia. The difference between GDA94 and GDA2020 on the ground is currently about 1.8 metres. Eventually, the ABS will phase out GDA94 boundaries.
- ASGS 2016 and 2011 digital boundaries are published using GDA94 only.
Geocode
A geocode describes the coordinates that define the position of an address point. Geocodes apply to a variety of address sites and features. It caters for the needs of a variety of users, with a particular focus on the needs of emergency and other essential service providers.
- Geocodes only need to be captured or assigned by the agency where they are appropriate to the agency’s purpose.
There are a number of elements needed to define a unique address geocode. Geocoded addresses fundamentally consist of coordinates associated with an address site feature. The geocode component of an address site shall contain:
(a) the datum and coordinate system being used (usually as metadata);
(b) the coordinates; and
(c) the address site feature being referenced (by individual record).
The geocode component should also contain geocode accuracy (by individual record).
The foundation of the Statistical Spatial Framework for Australia is the National Address Management Framework (NAMF). NAMF provides a common and consistent approach to establish a location (or geocode) from the address of each person, household or business in a dataset. This location should ideally be obtained from a physical address and not a mailing address.
Geocoded National Address File (G-NAF)
NAMF has been endorsed by all Australian government jurisdictions and utilises the Geocoded National Address File (G-NAF ®) as the source of address locations for service delivery. This dataset is also available under open data terms at www.data.gov.au.
G-NAF uses existing and recognised address sources (referred to as contributors) from the state and territory government land records and Commonwealth government organisations. A rigorous process is used that involves textual address comparison, matching and geospatial validation to provide both national consistency and national coverage. Maintenance activities are triggered through the receipt of updated address data from data contributors according to an agreed delivery schedule. At present, this schedule defines a quarterly update process. During the maintenance phase, contributed addresses are analysed and compared to existing records in G-NAF. This analysis and comparison gives rise to new records being inserted and existing records being updated or retired. The G-NAF maintenance pre-process takes the input files from reference datasets and contributor data and performs processing prior to data being processed by the G-NAF maintenance software.
- G-NAF Spatial Reference System: GDA94 and GDA2020
- Extents: North Bounding Latitude: -8 South Bounding Latitude: -45 West Bounding Longitude: +96 East Bounding Longitude: +168
Origin
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).
References
https://www.gnb.nsw.gov.au/__data/assets/pdf_file/0004/229216/NSW_Address_Policy_and_User_Manual_2021.pdf
https://www.spatial.nsw.gov.au/__data/assets/pdf_file/0005/219281/NSW_Standard_for_Spatially_Enabling_Information.pdf
https://www.spatial.nsw.gov.au/__data/assets/pdf_file/0005/229730/GDA2020_Information_Sheet.pdf
https://www.abs.gov.au/geography
https://www.abs.gov.au/statistics/standards/australian-statistical-geography-standard-asgs-edition-3/jul2021-jun2026
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| Value Domains Concepts implementing this Conceptual Domain | 29 |