LINZ - Improving Urban Cadastral Coordinates
In 2017 Land Information New Zealand (LINZ) began a three-year programme of work to improve the accuracy of its cadastral coordinates in urban areas, to better support high-precision cadastral applications.
Cadastral co-ordinates in urban areas have been largely based on measurements initially calculated by surveyors in the early 2000s.
Over time discrepancies of up to 10 cm have arisen in this data.
This is for a range of reasons including earthquakes, the installation of new and improved survey control marks, and slight inconsistencies between the original survey data and new data submitted by surveyors over the intervening years.
While these discrepancies in the data are small, they are large enough to have an impact on applications such as automated testing of new survey data, precise navigation to buried survey marks, and precise visualisation of property boundaries. To resolve these discrepancies, LINZ has set up a system to combine all the cadastral measurements in an area into a single computation, generating a more accurate and consistent set of coordinates.
Benefits of this work include:
- Reduced failures of automated business rules when new cadastral data is submitted to LINZ (this is because the new cadastral data is now far more consistent with existing data
- Improved consistency of digital property boundary mapping with other high precision spatial data, such as aerial imagery
- Additional cadastral control marks are available for use by surveyors
- Improved resilience of the cadastre to earthquakes, as land movements are easier to analyse when cadastral coordinates are accurate.
The improved data is recorded in the Landonline database and is also available via the LINZ Data Service, through updates to datasets such as NZ Primary Parcels.
Improvements to the urban cadastral coordinates are ongoing and expected to be completed by 2020.
For further information or you would like to provide feedback, please contact CRM_Geodetic@linz.govt.nz(link sends e-mail).