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Read and download specifications, standards, guidelines, and published documents. These resources are useful for students, researchers, geodetic service contractors and professionals who use New Zealand's geodetic network.

A lot of technical terms are used in New Zealand’s geodetic system. Find out about geodetic and vertical datums, geoids, projections, and coordinate transformations for accurate position and height measurements.

Determination of MHWS

There is no definitive method for establishing mean high-water springs (MHWS) boundaries – it requires a tailored approach that considers factors like hydraulic gradient, land type and the survey accuracy that is required.

Vertical datum relationship grids are reference surfaces that can be used to transform heights between the 13 official local vertical datums and New Zealand Vertical Datum 2016 (NZVD2016).

New Zealand Geodetic Datum 2000 (NZGD2000) coordinates include an ellipsoidal height measured using GNSS (global navigation satellite system) observations. Ellipsoidal heights often need to be converted to a vertical datum.

The Darwin Glacier Lambert Conformal 2000 projection (DGLC2000) was replaced by the McMurdo Sound Lambert Conformal 2000 projection (MSLC2000) on 21 March 2011.

New Zealand Geodetic Datum 1949 (NZGD1949) was a horizontal datum. Its coordinates were classified into orders according to observation type and survey network.

Before May 2010, normal-orthometric heights were categorised using orders based on observation method and survey significance. This order framework was replaced by the Standard for the Geospatial Accuracy Framework (LINZS25005) and Standard for Tiers, Classes and Orders of LINZ Data (LINZS25006), and has been adopted for New Zealand Vertical Datum 2016. The old framework continues to be used for the existing local vertical datum.

The New Zealand Geodetic Datum 2000 (NZGD2000) deformation model is used to adjust coordinates for ongoing crustal deformation. It takes into account tectonic motion and some major earthquakes to ensure that coordinates of survey marks and other features track the movement of those marks over time.

An important feature of a geodetic datum is the reference surface. The reference surface approximates the shape of the Earth, so that geodetic coordinates can be located on a curved surface. The most common reference surface for geodetic datums is an ellipsoid.

The mathematical parameters and equations used to convert New Zealand Map Grid coordinates to other datums and projections.

Coordinates can be transformed between projections within the same datum, or between projections using different datums.

How to transform heights between vertical datums.

Coordinates can be transformed between geodetic datums by using either a transformation grid or a similarity transformation. This section includes examples of transforming to and from New Zealand Geodetic Datum 2000 (NZGD2000).