1.Tiled Web Map

Also called as "slippy map" or "raster tile map".
is a map displayed in a browser by seamlessly joining dozens of individually requested image files over the Internet.

1.1 properties

Most tiled web maps follow certain Google Maps conventions:

• Tiles are 256x256 pixels
• At the outer most zoom level, 0, the entire world can be rendered in a single map tile.
• Each zoom level doubles in both dimensions, so a single tile is replaced by 4 tiles when zooming in. This means that about 22 zoom levels are sufficient for most practical purposes.
• The Web Mercator projection is used, with latitude limits of around 85 degrees.

The de facto OpenStreetMap standard, known as Slippy Map Tilenames^[2]

or XYZ follows these and adds more:

• An X and Y numbering scheme

• PNG images for tiles

• Images are served through a Web server, with a URL like

  http://.../Z/X/Y.png, where Z is the zoom level, and X and Y identify the tile.

1.2 Categories

1.2.1 Tile Map Service (TMS)

An early standard of tiled web map service. simpler than WMTS, and not backed by any official entity.

• Supported by :
  • OpenLayers
  • osgEarth
• Examples:
  • readymap(NASA BlueMarble+Landsat+Ocean Masking Layer)
    http://readymap.org/readymap/tiles/1.0.0.7/
    One difference is the y axis is positive southwards in TMS, and northwards in OpenStreetMap.

1.2.2 Web Map Tile Service(WMTS)

* a more recent OGC standard.
* a standard protocol for serving pre-rendered georeferenced map tiles over the internet.

1.2.3 The de facto XYZ standard referred to above.

1.2.4 TileJSON

a lightweight JSON description of all the parameters associated with a web map, created by MapBox

1.2.5 Bing Maps Tile System

using Quadkeys for addressing.

2. Web Map Service (WMS)

• Typically display a single large image.
• Low-effiency.