Satellite images map New Zealand

Snapshots from space form the basis of a new database that reports on the state of the New Zealand environment.

Snapshots from space form the basis of a new database that reports on the state of the New Zealand environment.

The Land Cover Database, which classifies Kiwi land use into 17 types, including exotic forest, urban areas, pasture and wetlands, will be used by government departments and regional councils for monitoring land use and environmental planning.

Terralink, a state-owned enterprise that is part of the former Department Of Survey and Land Information, developed the database with the Ministries of Agriculture and Forestry for about $1 million.

Some 146 satellite images of New Zealand were taken for the database by the French SPOT satellite over the summer of 1996-97 to provide coverage of cloud-free conditions. The images have a pixel size of 20m x 20m ground resolution, with a mimimum mapping size of one hectare.

Terralink "corrected" the large images with software called Eardas Imagine and Ground Control to account for the curvature of the earth and make them fit with well-known landmarks. The database was built using GIS software ArcInfo.

Terralink sales manager Lindsay Mason says the work took three to four years as the project needed to seek funding from regional councils and other government departments.

However, the next set of images that will be sought in 2001-2 should be cost much less as satellite technology becomes cheaper. The work will then be done every 5 to 10 years, depending on how quickly the environment changes.

"It's a point in New Zealand history that's fixed. Everything is able to be measured from now on," says Mason.

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