Web Map Tile Service
Overview:
The Web Map Tile Service (WMTS) is used to quickly return imagery tiles for a specified geographical extent. The WMTS specification relies upon the concept of the fact that the surface area of the earth can be broken down into predefined set of tiles, which together are referred to as a "tile matrix set". Each tile within the set is uniquely identifiable by a numeric row and column value.
There are several standard tile matrix set specifications, and they are closely related to an underlying Spatial References System (SRS). For example, tile matrix sets exist for EPSG:3395. WGS 84 / World Mercator. Therefore, is necessary to specify the reference tile matrix set for each WMTS request.
The tile matrix set, tile row, and tile column needs more information in order for the service to return an appropriate tile. This is because the service needs to know at what zoom level the specified row and column identifiers apply. A zoom level integer value translates to a corresponding Ground Sample Distance (GSD) on the earth so that the resolution of the imagery can be adjusted according to the apparent distance the tile is from the surface of the earth. Zoom levels start at the furthest distance from the earth’s surface and increase as the apparent distance to the earth’s surface decreases. Therefore, tiles at different zoom levels cover more surface area, and there are fewer and fewer tiles at higher zoom levels. The term "higher zoom level" refers to zoom levels that represent an increase in the distance from the earth.
In summary, a valid WMTS request will include a valid Connect ID, a format, a desired tile matrix set, a zoom level in the tile matrix set, the tile row identifier, and the tile column identifier.
This document is a profile of OGC 07-057r7, v.1.0.0, dated 2010-04-06. It defines specific Defence requirements, recommendations and guidelines for implementations of a Web Map Tile Service.
This profile:
- is for Web Map Tile Service implementations
- defines DGIWG-specific requirements, recommendations and guidelines
- enables independent and compliant software to ‘plug and play’ with each other
- offers three Operations:
- GetCapabilities (mandatory) - obtains Service Metadata
- GetMap (mandatory) - returns a map tile
- GetFeatureInfo (optional) - provides more information about map features from previous GetTile requests
Downloads:
| DGIWG # | Document Title (Click to Download) | Edition | Edition Date |
|---|---|---|---|
| 124 | Defence Profile of OGC Web Map Tile Service 1.0 | 1.0.0 | 2017-10-17 |