Improving the accuracy of the cadastre

Author: Jan Pierce
Date: 22 June 2010

LINZ is taking a leadership role in the emerging geospatial information sector, while also working to improve its own data.

A specific area we're focussing on is improving the accuracy of digital cadastral survey data so that boundaries in rural areas more accurately match the legal position.

A team of five LINZ staff will spend the next two years capturing survey data to improve the accuracy of identified high-priority areas.

The Spatial Data Improvement Project will initially focus on improving the quality of data in urban and intensive rural areas, where accuracy currently ranges from 1m to 100m. The aim is to have 95% of coordinates in the upgraded areas accurate to better than 2m.

The survey-accurate digital cadastre (SDC), which covers 70% of the parcels and 50% of the boundary points in New Zealand's cadastre, is accurate to at least 20cm. Most of these are in urban areas.

Because it's not possible to upgrade the entire cadastre in this time, we're focussing on extending the survey-accurate digital cadastre into areas where the benefit of high-accuracy data will be greatest.

This has involved extensive analysis of the current accuracy of our rural data, as well as consideration of feedback from a range of users of cadastral data, including surveyors, local authorities, GIS companies and the general public.

Immediate benefits

Improving data quality for the rural cadastre will enable wider and more confident application of this information.

Our work will increase the availability of high-accuracy digital cadastral data, and enable organisations using the data to concentrate on innovative spatial processing products and services like three dimensional or time-lapse modelling.

Users can expect to benefit from the upgrades almost immediately. As areas identified for upgrade are completed, the corrected data is loaded into LINZ databases that are made available to external users on a monthly basis.