ESRI has migrated its hosted ArcGIS Online maps to the Google Maps/Bing Maps tiling scheme. This change is in response to feedback from many ArcGIS users who have requested that ESRI use a common map tiling scheme matching other popular online map providers. The new maps will particularly enable ArcGIS web developers to more easily combine popular web map services with ArcGIS Online maps including those from Bing Maps, Google Maps, and other providers that use the same web map tiling scheme.
The existing maps in the ArcGIS Online tiling scheme will remain available for at least six months and, depending on demand, may remain available longer. Although the services will remain available, the content in these maps will no longer be updated.
For information on the common attributes for the Bing Maps/Google Maps tiling scheme, see Common attributes for maps using the Google Maps/Bing Maps tiling scheme.
Here are some details about the migration, including things you need to know, limitations, information on using the new services, and frequently asked questions.
ArcGIS Online maps are now hosted in Web Mercator Auxiliary Sphere with a well known ID (WKID) of 102100. Web Mercator Auxiliary Sphere (WKID 102100) handles datum transformations better than the original Web Mercator projection (WKID 102113), which is what some ArcGIS Online maps were previously in.
If you are caching data, you may want to consider using Web Mercator Auxiliary Sphere (WKID 102100). This will ensure that your caches overlay Bing Maps, Google Maps, and ArcGIS Online maps correctly. More information on how to set up a cache in Web Mercator Auxiliary Sphere (WKID 102100) is available in KB37329.
If you have already cached data in Web Mercator (WKID 102113), your cache may overlay ArcGIS Online maps correctly with no additional changes. If your cache does not overlay correctly, you will need to cache again using Web Mercator Auxiliary Sphere (WKID 102100). The likely reason that your cache does not overlay correctly is that the datum of your underlying data is not WGS 1984.
Like any projection, Web Mercator Auxiliary Sphere (WKID 102100) has inherent limitations. First, you will notice that no data is cached at the North or South Pole. This is a limitation of all Mercator projections. Also, area and distance measurements in Mercator will not be correct since the further north you take the measurement, the more distortion there is. When using ArcGIS Desktop, you can re-project the map to another projection that better handles area or length calculations. When using the Web APIs or ArcGIS Server, you can use the geometry service to re-project features before making area and length calculations. Re-projecting features should not be a problem since positional accuracy is preserved when projecting between Web Mercator Auxiliary Sphere and other coordinate systems.
If you are using ArcGIS Desktop 9.3 Service Pack 1 or ArcGIS Desktop 9.3.1 or higher, you will be able to view the new ArcGIS Online maps in Web Mercator Auxiliary Sphere (WKID102100) with no issues.
Web Mercator Auxiliary Sphere (WKID102100) is not supported in ArcGIS Desktop 9.2 or 9.3 without Service Pack 1 installed. If you are using ArcGIS Desktop 9.2 or 9.3 without Service Pack 1, you can continue to use the existing ArcGIS Online maps cached in WGS 1984. Note that these services are no longer being updated but in many cases will still provide a useful basemap reference.
If you are using the latest release of ArcGIS Explorer, you will be able to view the new ArcGIS Online maps with no issues.
With the ArcGIS Web APIs, you can to overlay maps in either Web Mercator Auxiliary Sphere (WKID 102100) or Web Mercator (WKID 102113) in the same application. In addition, these maps can be overlaid on a Bing Maps layer. The exception is when using the ArcGIS JavaScript Extension for the Google Maps API. Maps that are in WKID 102100 will not work. This issue will be fixed in the next release of the ArcGIS JavaScript Extension for the Google Maps API.
If you are using the ArcGIS Server .NET or Java ADF, there are some limitations. Within an application, all maps must be either in Web Mercator (WKID 102113) or Web Mercator Auxiliary Sphere (WKID102100), but they cannot be mixed. When using the ArcGIS Server .NET ADF, only maps in Web Mercator (WKID 102113) can be overlaid on Bing Maps; thus, you cannot overlay ArcGIS Online maps on top of Bing Maps. Bing Maps cannot be used with the Java ADF. These limitations will go away when ArcGIS Server 10 is released. At that time, you will be able to overlay services in the same way as the ArcGIS Web APIs.
