New Zealand's Geodetic System

The New Zealand geodetic system enables the accurate measurement and location of features in the physical world and ensures that different spatial datasets can be accurately correlated and compared within a consistent framework. It includes the national survey control system of ground reference points (e.g., trig stations) and their associated coordinates, official geodetic and vertical datums, and transformations between them. The geodetic system underpins the information represented on topographic maps and hydrographic charts and is essential to the coordinated allocation of property rights in the cadastre.

This page provides an index to information available online from LINZ about the geodetic system. Answers to frequently asked questions about geodesy are also available.

Datums and projections ensure that spatial data can be referenced in terms of a consistent system. The official geodetic datum in New Zealand is NZGD2000 and there are several official projections (NZTM2000 is used for new topographic mapping). Alternative and superseded datums and projections used in New Zealand are also described along with algorithms to transform coordinates between them.

The geodetic database can be searched to find information about geodetic marks used by surveyors in New Zealand. It is also available in a KML format for mark searching in Google Earth. The database provides information about the type of mark, its coordinates, location diagrams, beacons and site photographs. The geodetic mark data can also be freely downloaded.

Conversion of coordinates between the different coordinate and height systems used in New Zealand is available as an online service. Software is also available for download on an as is basis.

PositioNZ is the LINZ 30 station GNSS active control network. Through this site you can download 30 second GPS files (RINEX format) from the active control stations. These can be used with remote GPS station data to determine precise positions in terms of NZGD2000.

Publications, including standards, specifications, technical reports, fact sheets and other useful documents are available in PDF format.

The Surveyor-General has statutory functions to maintain a national geodetic system and a national survey control system. The national survey control system is realised as the networks of geodetic marks that are used to support the cadastral, topographic and hydrographic systems. The national geodetic system includes these marks as well as the various datums and projections that are used to uniquely reference them.

The requirements for the national geodetic and survey control systems are specified in Standards produced by the Surveyor-General. The systems are implemented in terms of the standards by the Customer Services group within LINZ.

Useful Links

This section covers some of those miscellaneous type geodetic questions. The sites here are not maintained or approved by LINZ but may be useful

• What is Geodesy? Geodesy for the Layman, a NGS publication last revised in 1984, may help.
• Magnetic declination can be computed anywhere in the world using this NOAA site
• The Star Almanac for Land Surveyors is a useful source of declination and right ascension information for stars, the coefficients can be downloaded if a copy of the book is purchased
• Geodesy acronyms - If you need some help with Geodesy related acronyms
• Great Circle distances and other calculations are available from Geoscience Australia