Introduction to Web Map Service

What Web Map Service Servers Provide

Web Map Service (WMS) servers follow a standard developed by the Open Geospatial Consortium, Inc.® (OGC) and provide access to a wealth of geospatial information. With maps from WMS servers, you can:

  • Use any publicly available WMS data

  • Easily adjust colors and styles to more clearly display information

  • Update your map to reflect the most recent data

  • Share your map with others

Mapping Toolbox™ software simplifies the process of WMS map creation by using a stored database of WMS servers. You can search the database for layers and servers that are of interest to you.

As an example, the WMS Global Mosaic map displays data from Landsat7 satellite scenes.

The Ozone Effect on Global Warming map displays data from the NASA Goddard Institute for Space Studies (GISS) computer model study.

Limitations of WMS Servers

A WMS server typically renders a layer as an RGB image. In some rare cases, you can request the actual data, rather than a pictorial representation, from a WMS server. Most often, you need to create either a Web Coverage Service (WCS) request, for raster data, or a Web Feature Service (WFS) request, for vector data. The Mapping Toolbox does not support WCS and WFS requests.

Basic WMS Terminology

  • Open Geospatial Consortium, Inc. (OGC)— An organization comprising companies, government agencies, and universities that defines specifications for providers of geospatial data and developers of software designed to access that data. The specifications ensure that providers and clients can talk to each other and thus promote the sharing of geospatial data worldwide. You can access the Web Map Server Implementation Specification at the OGC Web site.

  • Web Map Service — The OGC® defines a Web Map Service (WMS) as an entity that "produces maps of spatially referenced data dynamically from geographic information."

  • WMS server— A server that follows the guidelines of the OGC to render maps and return them to clients.

  • georeferenced — Tied to a specific location on the Earth.

  • raster data — Data represented as a matrix in which each element corresponds to a specific rectangular or quadrangular geographic area.

  • map — The OGC defines a map as "a portrayal of geographic information as a digital image file suitable for display on a computer screen."

  • raster map — Geographically referenced information stored as a regular array of cells.

  • layer — A data set containing a specific type of geographic information. Information can include temperature, elevation, weather, orthoimagery, boundaries, demographics, topography, transportation, environmental measurements, or various data from satellites.

  • capabilities document — An XML document containing metadata describing the geographic content offered by a server.

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