Quickstart Guide to OGC API - Tiles

About

This guide is intended to communicate the key pieces of the Tiles API standard so that implementors can get started without having to dig through the longer specification.

Introduction

OGC API - Tiles provides a standard way to describe web map tile sets for clients to consume. It is the successor to WMTS, updated to use JSON, in line with the spatial data on the web best practices. It also is designed to be a 'building block', that can plug into the OGC API suite, but can also be used as a standalone piece. It's also similar to TileJSON, adding the ability to handle alternate projections and fitting into the OGC API suite of standards.

Tiles Description Link

Any resource that is represented in JSON can provide a link to a ‘Tiles Description’ JSON object that provides the necessary metadata to enable a client application to formulate a tile request. This could be an OGC Collection, OGC Item (from OGC API - Features), or a custom resource (even an ‘ephemeral’ resource like a search response). But the resource must have a links array that includes an object with a rel of ‘tiles’ and a type of ‘application/json’, and the href must return the Tiles Description object specified below.

  "links": [
    ...
    {
      "href": "http://data.example.com/collections/buildings/tiles",
      "rel": "tiles",
      "type": "application/json",
    }
  ]
}

This communicates to any client that the link is the tiles representation of this particular resource. The core specification shows a link in a buildings Collection, which will be the starting point for many. (TODO: possibly add more examples, perhaps at the bottom or in an /examples/ directory)

Tile Description Response

The response of this link type is the JSON object that contains the information to enable a client application to formulate a tile request that represents the resources that created the link. The current minimum response in the specification is:

{
  "tileMatrixSetLinks": [
    {
      "tileMatrixSet": "WorldMercatorWGS84Quad",
      "tileMatrixSetURI": "http://schemas.opengis.net/tms/1.0/json/examples/WorldMercatorWGS84Quad.json"
    }
  ],
  ...
  "links": [
    ...
    {
     "href": "http://data.example.com/collections/buildings/tiles/{tileMatrixSetId}/{tileMatrix}/{tileRow}/{tileCol}.png",
     "templated": true,
     "rel": "item",
     "type": "image/png",
   }
   ...
  ]
}

The specification provides advanced options in the tileMatrixSetLinks to specify your own projections and matrices. For now just use the exact example above if your data is in WebMercator XYZ (as most web tiles are).

TODO: Add info on how to make the template match your server. And clarify if people have to include the tileMatrixSetID if they just have one