Different users have different requirements of the data contained in the G-NAF(Geographic National Address File). NAVIGATE has engineered the G-NAF data sets and restructured the data for friendly and easy integration with clients GIS and Information Systems.
NAVIGATE uses the G-NAF (Geographic National Address File) product from PSMA Australia as the source for reference databases. The G-NAF is delivered to NAVIGATE as a highly normalised data model that includes a number of data tables and a series of associated look-up tables containing approximately 15 million addresses and geocodes. The structure used by PSMA is well suited to compiling and checking the G-NAF, but most GIS users require a simpler “flattened” structure that facilitates easy and simultaneous access to all relevant parts of an address record without writing multi-table queries. NAVIGATE has taken the 30 plus tables that ship with G-NAF and combined them into a single table that forms core of our G-NAF product suite.
The primary components of G-NAF Flat are the individual address components joined to their most precise location. This is usually an “Address-Site Geocode” (ie the actual address point) but may be the “Street-Locality Geocode” (a central location on the street centreline within the locality) or just the “Locality Geocode” (centre point of the locality) if that is the best available. The information about which geocode has been adopted is recorded in a status field so the user is able to appreciate the level of spatial accuracy of each G-NAF Flat location.
The geocodes are expressed in terms of longitude and latitude coordinates in decimal degrees. NAVIGATE has generated a point geometry for each geocode that can be spatially indexed, displayed and analysed.
G-NAF contains address information provided by several contributors. There are understandably some inconsistencies in the address nomenclature and conventions used around the country. For example localities containing MOUNT as part of their name may also use the abbreviation MT. To provide the best possible reference dataset for geocoding customer data these types of variations have been standardised in NAVIGATE’s G-NAF products. The address parser in our geocoding kit for ESRI uses these same conventions for input address standardisation to maximise match potential with customer suburbs and street names.
Essentially G-NAF Flat can be thought of as the whole of G-NAF combined into a single table plus extra columns added by NAVIGATE. The extra columns are used to enhance the address information and the capability for address matching when used as a geocoding reference set. The complete dataset contains over a billion cells so various subsets are available to meet the needs of our clients.