Kōrero: Modern mapping and surveying

Whārangi 6. Later developments

Ngā whakaahua me ngā rauemi katoa o tēnei kōrero

Administrative changes

In 1987 the government’s surveying, mapping and land information services became a separate department, the Department of Survey and Land Information (DOSLI). Like other government agencies, DOSLI was expected to try and cover the costs of items it produced, so prices for maps and survey plans increased. It also established two digital databases, one of cadastral (land-parcel boundaries) and one of topographical information. However, changes in policy in the late 1990s, which made access to such databases easier and cheaper, opened up the market for map production to more smaller, non-government organisations.

In 1996 DOSLI was further restructured into two separate organisations, Land Information New Zealand (LINZ) and Terralink NZ Limited. LINZ became responsible for the policy and statutory parts of the land information system, whereas Terralink was set up as a state-owned enterprise to provide, on a commercial basis, the surveying and mapping functions previously done by DOSLI.

Terralink was sold in 2001. In 2008 it operated as a private company, Terralink International, supplying maps, aerial and satellite imagery and property information.

LINZ retained responsibility for providing an authoritative record of the natural and built environments, primarily for defence, emergency services, civil defence and local authorities. Its digital topographic database held all the current topographical data for New Zealand at a 1:50,000 scale, and in 2008 was available online through NZTopoOnline.

In June 2011 LINZ made their topographic, hydrographic and geodetic data and a selection of property-related data freely available via the LINZ Data Service. The data was available under a Creative Commons Attribution licence, so anyone could access and use it to create maps as long as they acknowledged the source.

Digital technology

Computerisation has had a major impact on mapping. From the 1960s digital equipment gradually increased the speed and accuracy of map production. The first fully digital map to be produced in New Zealand was one of Masterton, put out by the Department of Scientific and Industrial Research in 1986.

Computers can store large amounts of geographical data, which can then be used in a number of ways, including in maps and to create three-dimensional models of the land. Changes to printing technology have also made the production of maps easier. Maps can be provided online and customised to suit the user’s purposes. In 2008, a number of small New Zealand companies offered various mapping services. The opening up of the LINZ data sets in the 2000s had the potential to expand this further.

Satellite imagery

In 1972 the United States began the Landsat programme, recording information about the earth from an orbiting satellite, Landsat 1. The programme continued in the 2000s with Landsat 5 and 7. The first satellite images of New Zealand were taken in 1974, and by the 2000s a number of satellite imaging programmes could be accessed.

Satellite images are not photographs, but digital records of the different wavelengths of radiation emanating from the earth. To create a visual image, the data needs to be decoded. By assigning a wavelength to a particular colour, cartographers can highlight different features. These images are extremely useful for mapping things such as forestry or agriculture and for recording changes in the environment over time.

Global positioning system (GPS)

GPS, developed by the United States Department of Defense, enables any point on the globe to be accurately located by reference to at least four of 30 orbiting satellites. New Zealand’s first survey using GPS was done in Fiordland in 1986. During the 2000s a network of 32 GPS receivers was established across the country, providing points of the highest accuracy within the New Zealand Geodetic Datum 2000.

NZGD2000 and NZTM2000

In 1998 work began on a new geodetic datum (a mathematical model of the earth’s surface), NZGD2000, which replaced the New Zealand Geodetic Datum 1949. As survey equipment improved, the 1949 datum’s accuracy had come into question. It was also a local datum – it reasonably approximated the New Zealand region but was less useful with satellite technology based on global models. In 2001 a new map projection was also adopted, the New Zealand Transverse Mercator 2000 (NZTM2000), based on the new datum.

Me pēnei te tohu i te whārangi:

Melanie Lovell-Smith, 'Modern mapping and surveying - Later developments', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/modern-mapping-and-surveying/page-6 (accessed 26 May 2024)

He kōrero nā Melanie Lovell-Smith, i tāngia i te 24 Nov 2008, updated 1 Aug 2018