Technical Description

Local Government Areas is created through processing LGA data sourced from Australia’s States and Territories. Source attributes are mapped and standardised to provide a coherent definition across the jurisdiction supplies, with associated geometry being cleaned and processed to output a topologically consistent layer of Australia’s LGA boundaries at a national scale. Additional attributes have been generated and integrated by Geoscape to support the jurisdictional information as well as to provide convenience in the use and representation of the dataset. Local Government Areas is updated and released regularly and has integrated relationships with other Geoscape Products. Further information regarding attributes, quality, coverage and product release details are outlined below.

Linkages

This product is integrated with the following Geoscape products:

• Localities

• Wards

• Addressing Service

The joins used to link to these products are shown below, with attributes used in the joins described.

Attributes

LGA Name

The LGA Name attribute provides the name of the Local Government Area in Title Case (e.g. ‘Warren Shire Council’, ‘Bega Valley Shire Council’, ‘Randwick City Council’). Geoscape has provided these names with reference to jurisdictional definitions.

LGA Abbreviated Name

The LGA abbreviated name attribute provides the abbreviated name of the Local Government Area in Title Case (e.g. ‘Warren’, ‘Bega Valley’, ‘Randwick’). Geoscape has provided these names with reference to jurisdictional definitions. Data Model

Data Model

Data Dictionary

lga

Attribute	Data Type	Description	Primary Key	Mandatory Field	10 Character Alias
lga_polygon_pid	Character String (15)	Unique persistent identifier for the LGA polygon.	Y	Y	LG_PLY_PID
lga_pid	Character String (15)	Persistent identifier for the LGA.	N	Y	LGA_PID
date_created	Date	The date the record is first introduced to the Geoscape product.	N	Y	DT_CREATE
lga_name	Character String (75)	The name of the LGA.	N	Y	LGA_NAME
lga_abb_name	Character String (50)	The abbreviated LGA name.	N	Y	ABB_NAME
state	Character String (3)	The abbreviated name of the State or Territory that the LGA spatially resides within.	N	Y	STATE
geometry	Polygon (2D)	The geometry of the polygon.	N	Y	GEOMETRY

lga_locality

Attribute	Data Type	Description	Primary Key	Mandatory Field	10 Character Alias
lga_locality_pid	Character String (15)	Persistent identifier for each LGA to Locality link.	Y	Y	LG_LOC_PID
date_created	Date	The date the relationship was first built between the LGA and Locality in PSMA’s data platform.	N	Y	DT_CREATE
lga_pid	Character String (15)	The Persistent Identifier for the LGA.	N	Y	LGA_PID
locality_pid	Character String (15)	The Persistent Identifier for the Locality.	N	Y	LOC_PID

Domain Values

state

Domain Value	Description
NSW	The data is located within the state of New South Wales.
NT	The data is located within the Northern Territory.
OT	The data is located within the Other Territories classification. Other Territories covers the external Australian territories of Cocos (Keeling) Islands and Christmas Island.
QLD	The data is located within the state of Queensland.
SA	The data is located within the state of South Australia.
TAS	The data is located within the state of Tasmania.
VIC	The data is located within the state of Victoria.
WA	The data is located within the state of Western Australia.

Update Frequency

This product is continuously updated and released with the most up to date data available on a quarterly schedule in the months of February, May, August and November.

Data Quality

Positional Accuracy

This product has been created by combining LGA boundary information from multiple jurisdictional sources. Each jurisdiction has a range of collection methodologies to capture the digital representation of the LGA boundary. The varying approaches to maintaining the boundaries will contribute to the dataset’s overall accuracy. As the jurisdiction capture programs improve or otherwise change LGA boundaries, we incorporate these changes as an update into the product and the positional accuracy is maintained. Geoscape makes minor changes only where they are required to create valid features described in Geometry Validity.

Coordinates Referencing the GDA2020 Datum

Spatial features referencing the GDA2020 datum are produced using a coordinate transformation from the GDA94 datum using the following parameters.

• shift_x = 0.06155,

• shift_y = -0.01087,

• shift_z = -0.04019,

• rotate_x = -0.0394924,

• rotate_y = -0.0327221,

• rotate_z = -0.0328979,

• scale_adjust = -0.009994

Geometry Validity

The geometry is validated to ensure polygons are a valid representation and free of self-intersection. Issues being detected and resolved include spikes, bow ties, duplicate vertices, null geometries, multipart geometries and self-contacts. Gaps and overlaps are resolved for polygons within each State or Territory. Gaps and overlaps between State or Territory boundaries are not resolved. Where valid holes are present in the jurisdictional data, such as lakes or rivers, these holes are retained.

Polygon orientation conforms to the following specifications:

• OGC Simple Feature Access Specification v1.2.1 [Section - 6.1.11.1]

• The GeoJSON Specification RFC7946 [Section 3.1.6 dot point 4]

This means the polygon outer boundary will be counter clockwise and the inner boundary will be clockwise for file formats that support the above standards.

Further Comments

Local Government Areas has been processed to assure all polygons are stored as single part features to improve compatibility with a range of software applications. As a result, there can be a duplication of the lga_pid for some local government areas that are represented by multiple, separate, polygons.

Extent/Geographic Description

The spatial coverage of this dataset includes Australia’s land mass and surrounding offshore islands.

The Bounding Box for this data is as follows:

• North bounding latitude: -8˚

• South bounding latitude: -45˚

• East bounding longitude: 168˚

• West bounding longitude: 96˚

A detailed description of the coverage for each State and Territory is provided in the table below.

Spatial Reference System

GDA94

Horizontal Datum: The Geocentric Datum of Australia 1994 (GDA94) is the target horizontal datum.

Coordinate System: Geographic Coordinate System Geocentric Datum of Australia 1994 (GDA94).

GDA2020

Horizontal Datum: The Geocentric Datum of Australia 2020 (GDA2020) is the target horizontal datum.

Coordinate System: Geographic Coordinate System Geocentric Datum of Australia 2020 (GDA2020).

Delivery Format

The data is provided at a National and a State/Territory level, depending on the file format selected. The data is made available in the File Geodatabase, GeoJSON, ESRI Shapefile and MapInfo TAB formats described below.

Format	National	State/Territory
File Geodatabase	Yes	Yes
GeoJSON	Yes	Yes
ESRI Shapefile		Yes
MapInfo TAB		Yes

File Geodatabase

Format name

File Geodatabase – ESRI™

Specification

This format includes files with the following extensions: *.gdb

ESRI File Geodatabase Technical Description. Follow this link: http://desktop.arcgis.com/en/desktop/latest/manage-data/administer-file-gdbs/file-geodatabases.htm

Language

English

GeoJSON

Format name

GeoJSON

Specification

This format includes files with the following extensions: *.geojson

GeoJSON specification: https://tools.ietf.org/html/rfc7946

Language

English

Note

The GeoJSON specification states that the coordinate reference system for all GeoJSON coordinates is:

“a geographic coordinate reference system, using the World Geodetic System 1984 (WGS 84) datum, with longitude and latitude units of decimal degrees”

Local Government Areas will be provided with coordinates using the datum selected for download (GDA94/GDA2020) with longitude and latitude units of decimal degrees.

JSON

Format name

JSON

Specification

This format includes files with the following extensions: *.json

JSON specification: https://www.json.org/json-en.html

Language

English

ESRI Shapefile

Format name

Shape – ESRI™

Specification

This format includes files with the following extensions: *.shp, *.shx, *.dbf

ESRI Shapefile Technical Description, an ESRI White Paper, July 1998. Follow this link: https://www.esri.com/library/whitepapers/pdfs/shapefile.pdf

Language

English

MapInfo TAB

Format name

TAB – MapInfo Professional™

Specification

This format includes files with the following extensions: *.tab, *.dat, *.id, *.map

The MapInfo TAB format is a popular geospatial vector data format for geographic information systems software. It is developed and regulated by MapInfo as a proprietary format. TAB files support geospatial standards such as Open GIS, the OGC, ISO, W3C and others.

Language

English

Product Versioning

The product versioning is managed through incrementing when there is a change to the product schema or a significant change in data population, these are described further below:

• A schema change can affect a major or minor increment to the versioning. Additive changes (changes that won’t break customers’ ability to work with the data) will be incremented with a minor version increment, an example is the addition of a new attribute. Removal of attributes or changing the structure of the schema will enact a major change to identify that this requires the attention of all customers and partners.

• Where a significant geography of Australia either has a new population of data for an attribute or is populated from a much higher quality source a minor increment will be applied to the product version.

Therefore, the product’s versioning will not increment with every data update. Published releases will have a name (e.g. ‘August 2021’) and will reference a version of the product (e.g. ‘1.0’).