Web Services Help

Web map services: Web Map Service is one of the OGC (Open Geospatial Consortium, Inc) standards. WMS is a web-based tool that produces and serves digital maps. In the past, analyzing and creating maps was a slow and labor-intensive process. Now with Global Positioning Systems and other digital methods of gathering geographical data, digital mapping has become an important component in several fields. The WMS specification is a web-based protocol that allows communication of map-style data between a server and a client.

WMS Implementation Specification provides three operations (GetCapabilities, GetMap, and GetFeatureInfo) in support of the creation and display of registered and superimposed map-like views of information that come simultaneously from multiple remote and heterogeneous sources.

Users of ESRI products such as ArcExplorer or ArcMap or ArcCatalog can view base layers via the Internet without having to download the mapping files. The general routine to use ArcGIS ArcCatalog to set up a WMS (and WFS) serve. The steps are the followings (using www.mapwv.gov as example).

In ArcMap, the service can be added using the menu sequence “Add Data>GIS Servers”, double click on www.mapwv.gov.  A list of services will be available under www.mapwv.gov tree. Select one service to view the data. In general, WMS services are with icon .

For example, selecting the Map Service name “WV_SAMB_Orthophotos_2003_UTM83” from the www.mapwv.gov Map Server will add the statewide, 2-foot color aerial photos flown in spring 2003 into ArcMap. The following is the screen shot of WV_Elevation_30m_UTM83 in ArcMap.

The WMS image service can be viewed in ArcCatalog as well. After you add a WMS server, you can view the service image by using preview tab in Arccatalog. See the right image for reference. The image service is from WV DEP.

For developers to access WMS services with Internet application, the LAYER ID will be used. The syntax of calling a WMS service is like this: