SouthPAN coordinates

SouthPAN uses international, dynamic datums for its coordinates. New Zealand’s official coordinates are published in NZGD2000, which models and removes the effects of tectonic movement and earthquakes so that positions remain stable for users.

SouthPAN coordinates and NZGD2000

If you compare SouthPAN‑enabled coordinates with LINZ‑published coordinates, you may see a difference. This is normally because they are in different reference frames. 

SouthPAN-enabled receivers output coordinates in WGS84 for L1/L5 signals (or ITRF2014 for PPP). These are global, time‑dependent datums. LINZ publishes official coordinates in NZGD2000, which is aligned to ITRF96 at epoch 2000.0 and uses a deformation model to account for plate motion and earthquakes.

Because these systems change differently over time, SouthPAN coordinates will not match NZGD2000 unless they are transformed using the NZGD2000 deformation model. To achieve agreement better than about 2 metres, convert SouthPAN coordinates to NZGD2000 using the LINZ Online Coordinate Converter.

Online Coordinate Converter

Transformations in software

Many GIS and positioning applications do not apply the NZGD2000 deformation model when converting to or from WGS84 or ITRF. This can result in coordinates being incorrect by several metres.

Examples:

  • QGIS currently transforms between WGS84 and NZGD2000 but does not apply the deformation model.
  • Trimble Business Center does apply the deformation model and produces correct NZGD2000 coordinates.
  • If you need to send NZGD2000 coordinates to a SouthPAN-enabled device, you will need to convert them back to WGS84.

If your software does not apply the deformation model, convert your coordinates using the LINZ Online Coordinate Converter before loading them into your GIS. The converter applies both the correct datum transformation and the NZGD2000 deformation model.

To use the Online Coordinate Converter to transform SouthPAN coordinates to NZGD2000

  1. Enter your SouthPAN coordinates and select input datum (WGS84 for L1/L5 signals).
  2. Choose NZGD2000 as the output datum.
  3. Download or copy the converted result.

To use the Online Coordinate Converter to transform NZGD2000 to a SouthPAN datum

  1. Enter your NZGD2000 coordinates and select NZGD2000 as the input datum
  2. Choose the required output datum (WGS84).
  3. Download or copy the converted result.

Building your own transformations

For users developing workflows or processing bulk datasets, the standard procedures are:

To transform WGS84 to NZGD2000

  1. Convert the coordinate at date (t) to ITRF96.
  2. Apply the NZGD2000 deformation model at date t

To transform NZGD2000 to WGS84

  1. Add the NZGD2000 deformation model at date (t) to obtain an ITRF96 coordinate.
  2. Convert that coordinate to WGS84

More information 

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