Choosing a basemap

A basemap provides a background of geographical context for the content that you want to display in a map. When you create a new map, you can choose which basemap you want to use. You can change the basemap of the current map at any time by using the basemap gallery or using your own layer as the basemap.

Selecting a basemap from the gallery

The basemap gallery includes a variety of choices including topography, imagery, and streets.

To choose a basemap from the gallery, follow the steps below.

Steps:

1. Open the ArcGIS.com map viewer, for example, by clicking the Map button.
2. Click the Basemap button.
3. Click the thumbnail of the basemap you want to use in your map.
4. View information about a basemap in the gallery by first adding it to your map.
   1. Click the Details button.
   2. Click the Show Content button.
   3. Click the arrow to the right of the basemap name.
   4. Click Description.

Using your own basemap

In addition to the basemap gallery, you can also use your own basemap from ArcGIS Server services and OGC layers. When you use your own basemap, your map uses the projection of that basemap instead of Web Mercator, the projection of the ArcGIS.com map viewer.

To use your own basemap, follow the steps below.

Steps:

1. Click the Add button. You can add a basemap by searching for an existing layer or adding a layer from the web.
2. To search for an existing layer, choose Search for Layers.
   1. Enter keywords within the Find field.
   2. Choose where you want to search for layers.
   3. Click the Go button. A list of layers appears that relate to the keywords you entered.
   4. Click the title of the layer you want as your basemap.
   5. Choose Use as Basemap in the pop-up summary window that appears.
   6. Click Done Adding Layers to close the Search for layers to add window.
3. To add a layer from the web, choose Add Layer from Web.
   1. Choose the type of data the layer references.
   2. Enter the layer's web address in the URL field.
   3. Click the Go button. When the ArcGIS.com map viewer finds the layer, its name appears in the results.
   4. Check the box next to Use as Basemap.

Basemap considerations

• The ArcGIS.com map viewer can't display layers in a map without a working basemap because the basemap establishes the coordinate system of the map. Once you save a web map with a basemap, the map viewer only uses that basemap; it doesn't revert to a default basemap if yours is unavailable. You can repair your web map by using a different basemap as long as the spatial reference of the bad and new basemap are the same. Repair your map by selecting a different basemap or using the URL parameter basemapURL. For more information about using the basemapURL, see Using URL parameters.
• When you use your own basemap, some of the zoom levels may be missing. This happens because the map displays the zoom levels of the current basemap, for example, the World Topographic basemap. To see the additional zoom levels in the basemap you've added, save your map, close the ArcGIS.com map viewer page (for example, go to the Gallery), then reopen the map. The additional zoom levels appear.
• If your OGC WMS layer uses a projection other than Web Mercator, the projection of the default World Topographic basemap, the ArcGIS.com map viewer attempts to use a compatible basemap. If your layer is in GCS WGS84, the ArcGIS.com map viewer uses the GCS WGS84 World Imagery basemap. If your OGC layer is in a coordinate system other than Web Mercator or GCS WGS84, your layer is used as the basemap. You can use a different basemap as long as it is compatible with your layer's projection. If a basemap in the gallery is not compatible, the ArcGIS.com map viewer will not add it to your map; instead, you will see an error message letting you know your layer is not compatible with the basemap's coordinate system.
• When you add an OGC WMS layer to your map, you may get an error that the layer's coordinate system doesn't align with that of the basemap. This error message usually appears if you have added layers to your map, then add an OGC (WMS) layer that isn't in Web Mercator, the projection of the basemaps in the ArcGIS.com map viewer gallery. Create a new map and add your OGC (WMS) layer first. If your layer is in GCS WGS84, the ArcGIS.com map viewer uses the GCS WGS84 World Imagery basemap. If your OGC layer is in a coordinate system other than Web Mercator or GCS WGS84, your layer is used as the basemap. Now you can add additional layers.