In addition to contour lines, relief shading helps visualise the terrain. Hills and valleys are shaded as if they were illuminated from the north-west.
Relief layers were generated for each sheet, and specifically for use in the Topo50 map series. There may be subtle differences in the relief shading of adjacent map sheets. Where no contour information exists, relief shading has not been produced.
The Topo50 map series provides topographic mapping for the New Zealand mainland, the Chatham Islands, and offshore islands at 1:50,000 scale (some of the islands at 1:25,000).
Further information on Topo50: http://www.linz.govt.nz/topography/topo-maps/topo50
LINZ and our predecessors have been responsible for national topographic mapping in New Zealand for more than a hundred years.
The first digital data was created in the late 80's and early 90's by scanning the 1:50,000 maps that existed at the time (known as the NZMS 260 series, which replaced the imperial NZMS 1 series at 1inch to 1 mile)
The raw data was created by photogrammetrists who from 1974 to 1997 mapped the country from overlapping pairs of aerial photographs. Cartographers then took the data and added symbols and text, and created the colour separations needed to produce the printed maps.
From 1994 to 2006 LINZ used orthophotos to update the map data. Today the map data is updated primarily from aerial and satellite imagery, and data supplied from Department of Conservation, Transit NZ and others.
LINZ releases regular updates of the Topo50 maps and data; for details refer http://www.linz.govt.nz/topography/topo-maps/topo50/update-history