Slope data layer used in the creation of Land Environments of New Zealand (LENZ) classification. The classification layers have been made publicly available by the Ministry for the Environment (see https://data.mfe.govt.nz/layers/?q=LENZ for to access these layers).

This slope data layer is measured in degrees and was created from a 25-metre digital elevation model (DEM) fitted to 20-m digital contour data derived from New Zealand's NZMS 260 map series using in-house software developed at Landcare Research.

All contours were originally derived photogrammetrically from stereo photographs for final map reproduction at a scale of 1: 50 000. Additional intermediate contours and spot heights were used in generating the DEM where available, while coastlines and shorelines (for lakes greater than 10 ha in extent) were used to constrain the DEM surface around water bodies. The linear interpolation method used to create the DEM threads contours through the cells before interpolation so that any cell intersected by a contour will be given the elevation value of that contour, leading to a high percentage of cells with elevations that are multiples of 20 or 10 in steep areas.

Additional details are defined in the attached LENZ Technical Guide.