This provides a polygon coastline and islands layer which is based on the Topo50 products. It is a combination of the following layers:
- [NZ Coastlines (Topo 1:50k)](http://data.linz.govt.nz/layer/50258-nz-coastlines-topo-150k/) - [NZ Island Polygons (Topo 1:50k)](http://data.linz.govt.nz/layer/50288-nz-island-polygons-topo-150k/) - [NZ Auckland Is Island Polygons (Topo, 1:50k)](http://data.linz.govt.nz/layer/50959-nz-auckland-is-island-polygons-topo-150k/) - [NZ Campbell Is / Motu Ihupuku Island Polygons (Topo, 1:50k)](http://data.linz.govt.nz/layer/50932-nz-campbell-is-motu-ihupuku-island-polygons-topo-150k/) - [NZ Antipodes Is Island Polygons (Topo, 1:25k)](http://data.linz.govt.nz/layer/50978-nz-antipodes-is-island-polygons-topo-125k/) - [NZ Kermadec Is Island Polygons (Topo, 1:25k)](http://data.linz.govt.nz/layer/50908-nz-kermadec-is-island-polygons-topo-125k/) - [NZ Bounty Is Island Polygons (Topo, 1:25k)](http://data.linz.govt.nz/layer/50992-nz-bounty-is-island-polygons-topo-125k/) - [NZ Snares Is / Tini Heke Island Polygons (Topo, 1:25k)](http://data.linz.govt.nz/layer/50893-nz-snares-is-tini-heke-island-polygons-topo-125k/) - [NZ Chatham Is island polygons (Topo, 1:50k)](http://data.linz.govt.nz/layer/50086-nz-chatham-is-island-polygons-topo-150k/)
This topographic coastline is the line forming the boundary between the land and sea, defined by mean high water.
Islands from the NZ Island Polygons layer that lie within the NZ Coastline and Chatham Islands areas (i.e. islands in lakes, rivers and estuaries) have been removed.
The GIS workflow to create the layer is:
1. NZ Coastlines were converted from a polyline to a polygon using a polyline to polygon tool. 2. The resulting coastal polygon was then used as an input into an erase tool and run against the NZ Island Polygon layer to remove all islands lying within the NZ Mainland and Stewart Island. 3. This was then merged with the NZ Chatham Is island polygons (Topo, 1:50k) that have had the islands within the main island polygon removed, NZ Auckland Is Island Polygons (Topo, 1:50k), NZ Campbell Is / Motu Ihupuku Island, NZ Antipodes Is Island Polygons (Topo, 1:25k), NZ Kermadec Is Island Polygons (Topo, 1:25k), NZ Bounty Is Island Polygons (Topo, 1:25k) and NZ Snares Is / Tini Heke Island Polygons (Topo, 1:25k) layers using a merge tool. 4. Lake Onoke from the NZ Lake Polygons (Topo 1:50k) layer and Te Whanga Lagoon from the NZ Chatham Is lagoon polygons (Topo, 1:50k) layer were then erased from the resultant polygon layer to include these two water bodies in the coastline definition.
For more detailed description of each layer refer to the layer urls above.
--- **APIs and web services** This dataset is available via ArcGIS Online and ArcGIS REST services, as well as our standard APIs. [LDS APIs and OGC web services](https://data.linz.govt.nz/layer/51153/webservices/) [ArcGIS Online map services](https://basedatanz.maps.arcgis.com/home/item.html?id=3b4ed8eadb8241989056bdb909d1a9c6) [ArcGIS REST API](https://services7.arcgis.com/jI87xPT7G1AGV8Uo/arcgis/rest/services/)
LINZ and our predecessors have been responsible for national topographic mapping in New Zealand for more than a hundred years.
The first digital data at 1:50,000 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
Some features are subject to change more than others. For example in any given map revision, it is likely that road data will undergo more change than, for example, fumeroles. However, all data is examined during a full data revision.