In the ArcGIS Map Web Part, a cached map service is always used as the map's background - commonly referred to as the web part's base map. Cached map services are web services for which map images have been pre-generated across the range of areas and scales within which the service is expected to be used. Since the map images, also known as map tiles, have been pre-calculated, cached map services provide superior performance without compromising cartographic quality.

Choose a Base Map

You can select the map service(s) that will be used for the Map Web Part's base map when you modify the web part. In the configuration dialog, three options are provided: ArcGIS Online, Bing Maps, or ArcGIS Server:

The base map options correspond to map services as follows:

• ArcGIS Online - A configurable set of three ArcGIS Online base map services. When the Map Web Part is configured with this option, users will be able to choose between these three services with the radio buttons in the upper right corner of the web part.
• Bing Maps - The three Bing Maps map services - roads, aerial, and aerial with labels - from either the staging or production server. As with the ArcGIS Online option, users will be able to choose between the three base maps if this option is selected.
• ArcGIS Server - An ArcGIS Server map service that is specified by the ESRI Base Maps list, or that you specify when configuring the Map Web Part. This can be any ArcGIS Server cached map service that can be connected to from the SharePoint host server.

Set the default base map

If you select the ArcGIS Online or Bing Maps base map option, users will be able to toggle between a set of three base maps. When you modify the web part, you can select which of these three base maps will be shown by default when the web part loads. Simply select the radio button next to the base map layer of your choice and apply the changes to the web part by clicking OK or Apply. When a user loads the page that contains the web part, the base map you have specified will be selected.

Set the default map extent

The default extent of the map can be set at any point during configuration. Simply navigate the map to so that it is set to an area of your choice and apply the change to the part by clicking OK or Apply. Then, whenever a user loads the web part, the map extent you defined will display by default.