Open Geospatial Consortium (OGC) Web Mapping Services (WMS)
The Open Geospatial Consortium (OGC) has defined Web Mapping Service (WMS) specification protocols for the transfer of geospatial data from servers to client applications. A Web Map Service (WMS) produces an image (e.g. GIF, JPG) of geospatial data.
WMS gives clients access to an image of data without storing a local copy of the dataset. Using a specially structured http request, you can call a dataset (eg. orthoimagery, highways) into your GIS software application.
Receiving an image of the data works well for imagery and other raster data, but means that standard GIS analysis is not feasible using WMS. Web Feature Services (WFS) protocols, on the other hand, do support actual data feature transfer, but very few services currently exist.
NC Dept. of Agriculture WMS of NC's topo maps (DRGs) within ArcMap. WMS links are below.
- ESRI Interoperability and Standards website - links to the add-on download and support docs
- Open Geospatial Consortium, Inc. (OGC) - developed the WMS standards
- There are a number of other websites with WMS information that can be found by searching Google.
To connect to a WMS, select and copy a WMS link and paste the link where your software asks to specify a WMS URL.
If using ArcGIS:
- Click "Add Data" and in the "Look In" window, scroll down near the bottom to "GIS Servers"
- Choose "Add WMS Server" or one of the other options if you know the host server is running one of those platforms.
- In the window that opens (pictured at right), copy/paste the WMS URL link and click "Get Layers" to initiate a connection. Once the Server Layers window is populated, click OK.
NC WMS Data
- NC OneMap hosts or links to numerous web mapping services provided within North Carolina, including statewide orthoimagery and post-hurricane imagery:
- Search NC OneMap for WMS services
- NC OneMap Web Services homepage - The "Questions" link contains very valuable instructions and tips, while the "Web Services" link lists the available data services options.
- The North Carolina Department of Agriculture and Consumer Services hosts WMS services that provide data coverage for NC. Services available include:
WMS Indexes and Servers
- geopole.org - Global Catalog
"Find and Monitor Public Map Services" Services appear to be added by crawlers that add to the site index.
- ArcGIS.com - Global Catalog
ESRI's clearinghouse for map services. Services get added to this index from user contributions.
- geo.data.gov - US Catalog
Data originates primarily from government and academic sources. Click Advanced Search Options, and then check the box for "Live Data and Maps" specify "WMS" as the keyword. In the search results, go into the details of any WMS service entry and find the WMS URL under "Service Availability"
- Skylab Mobilesystems - Global List
Very large lists of links - use Search tools.
- USGS Data - US List
Click the "Service Access List" links under each data category. The resulting pages will contain WMS links for connecting to WMS Servers. Data Categories are: Orthoimagery (High Resolution, NAIP), Elevation (NED), Land Cover