LDS web map tile service specifications

All you need to know about the parameters of the LINZ Data Service web map tile services to get you started using these services in web, mobile and GIS applications.

The LDS web map tile services makes access to data for basemaps and visualisations that much easier. This service allows you to directly incorporate LINZ data into your web, mobile or GIS application via pre-rendered map tiles.

LDS map tile services are available as a Web Map Tile Service (WMTS) for use in GIS applications and as a XYZ service for web and mobile mapping.

See below for links to step-by-step guides for using LINZ basemaps and map services in Javascript and GIS applications.

Map services overview

LDS web map tile services deliver:

  • fast access to pre-rendered, cached map tiles
  • authoritative and up-to-date tiled map data
  • data released under a Creative Commons Attribution 4.0 International licence
  • an open API for easy web, mobile and GIS integration
  • uses existing LDS API key system

Specifications

The LINZ Data Service tile service has been implemented to the following specifications:

  • OGC-compliant WMTS version 1.0 implemented
  • Support for OGC WMTS tile requests and XYZ style tile requests
  • WGS 84 / Web Mercator projection for use in web development
  • NZTM2000 projection for use in localised projects or GIS applications
  • Support for RESTful requests (KVP and SOAP request interfaces are not supported)
  • Supports PNG image format for tiles
  • PNG tile returns to support transparency for data overlays
  • Uses Content Distribution Network (CDN) for fast serving of map tile images

Tile matrix sets

Most LDS map tile services are available in two projections - Web Mercator (EPSG:3857) and NZTM2000 (ESPG:2193). Each has its own tile matrix set that describes the zoom levels, scale and resolution for the pre-rendered, cached images that are returned.

See the LDS tile services tile set schema documents below for more information on the specifications of these tile sets.

WGS84 Web Mercator (EPSG:3857)

This tile set is most suitable for web mapping applications, and is compatible with the Google Map, OSM and Bing Maps tiles without need for re-projection or scaling. 

NZTM2000 (EPSG:2193)

This tile set is most useful for New Zealand geospatial professionals and can be used for desktop GIS mapping. It is also recommended for New Zealand mainland web applications when area and distances need to be well represented on the map. 

Responses

Tile image requests are returned from the tile cache as compressed PNGs. See the Tile services tile set definition document for information on image resolution (pixel size).

PNG format was chosen as it allows the quality of images to be maintained with relatively small file sizes, and supports making the tile background transparent which is important for overlaying datasets or combining multiple layers together.

PNG is the only format supplied. The LDS WMTS service does not support on-the-fly conversion of image formats.

When tiles outside the map coverage area are requested, any tile returned will be transparent. 

On demand cache

A tile is cached on the server only that tile has been requested by a user.

Tiles are also cached on a rolling basis. This means there may be some fluctuation in tile responses as tiles are cached during an initial request, drop off the cache store and are re-cached.

Data that comprise LDS map tile services is frequently updated. You may experience a temporary dip in performance as the cache is flushed and tiles are re-cached by users following a data update.

Rate limiting

To guarantee reasonable performance levels and to guard against overuse or abuse of LINZ’s free tile services, these services are rate limited. It is highly unlikely that rate limiting will impact the use of tile services in GIS applications.

Accessing LDS web map tile services

Tile services are available for our aerial photos, topographic maps, hydrographic chart images and property boundary datasets published on the LINZ Data Service.

To access these services you need to create a LDS API key. You can create multiple keys to use across this and other LDS APIs, such as our Web Feature Service.

Once you have created your key, you can use it within any LDS web service or API URL endpoint request. If you are logged into LDS and select a web service URL, your web service key is automatically populated in the URL.

Client-side authentication is not required, as LDS recognises you as a registered user of LDS tile services through the API key.

Selecting a map tile service

Simply select the ‘Services’ tab of any raaster dataset to view the available tile services and the request URLs, then copy and paste the relevant URL into your application.

WMTS specifications - service tab

If you are logged in to LDS and have already created an API key, your API key and the layer ID will be pre-populated in the URL for you.

Reference Category: Basemaps
Reference Tags: WMTS, Authentication, Cache, Specifications
Last Updated: 
11 October 2018