General
The New Zealand Land Cover Database (LCDB) is a digital map of the surface of New Zealand created using satellite imagery. It contains detailed information on categories of land cover and their boundaries and is a record of land cover changes over time. Two editions of the New Zealand Land Cover database have been completed (LCDB-1 and LCDB-2). These show the state of New Zealand’s land cover in 1996-1997 and in 2000-2001 respectively. LCDB-1 used SPOT 2 and SPOT 3 satellite imagery to resolve 16 land cover classes (Table 1). LCDB-2 was released in 2004 and used LANDSAT 7 ETM+ satellite imagery and the thematic classification was increased to 43 classes (Table 2). The increased thematic depth of LCDB-2 reflected the superior spectral resolution of the LANDSAT 7 sensor but many users observed a decline in classification accuracy. While both LCDB-1 and LCDB-2 included automation in their image preparation and early classification stages, both were primarily reliant, in their later stages of compilation, on visual inspection of imagery and manual digitizing. A further two editions of the LCDB will be produced under the current LCDB programme contract, and it is envisaged that future funding will be found for development beyond this.
Thematic detail LCDB-2 classes were designed to provide backward comparability with the earlier LCDB-1. Some of these classes proved to be unreliable to distinguish or less important for end use applications. The LCDB-3 classes resulted from a sequence of user forums conducted in 2010 and aims to address some of the issues with the LCDB-2 set while still maintaining comparability.
Land Cover classifications
of LCDB1 and LCDB2 and that of the proposed LCDB3
The rationalised classification means that, for example, mines will not be distinguished from dumps as they are in LCDB-2 and the age-class breakdown of exotic forests (of interest largely to the forestry industry) will not be maintained. More details on the exact translation of classes between LCDB-2 & 3 can be found in here. A map-to-image automated change detection process is being used to highlight areas for operator investigation.. This detection method often highlights errors present in LCDB-1 & 2 and correction of these errors is part of the LCDB-3 mapping process. A stakeholder check and revision process will be developed in consultation with the Steering Group and contributing stakeholders. This will allow stakeholders to contribute to a schedule of field checking and revision of a draft version of each new LCDB edition. Key stakeholder groups with knowledgeable field staff who have indicated support for this process include Regional Councils, Rural Fire Authorities and Dept of Conservation. By LCDB-5, field devices and the rural reach of mobile data networks are expected to be able to support an entirely on-line process for requesting field checking and revision. Through LCDB-3 and LCDB-4 online processes will be progressively developed and deployed to support this mode of operation, but it is recognised that support for off-line field processes will also be needed. The core products of this work, subject to changes agreed with the Steering group will be :
Accuracy An initial accuracy assessment of the LCDB v3.0 is now available. |
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