Designing a map to overlay ArcGIS Online services

If you'll be using the ArcGIS JavaScript API or the Web ADF to overlay your map on ArcGIS Online services, follow this workflow when you create your map:

Author the map

You'll originally create the map in ArcMap by adding data and symbolizing it appropriately. When designing the map, you need to use the same coordinate system and scales used by ArcGIS Online services.

Change the coordinate system to WGS 1984

The first thing you should do when designing the map is change the coordinate system to the same one used by ArcGIS Online services, which is WGS 1984. To change the coordinate system, follow these steps:

1. Right-click the data frame name in the ArcMap table of contents (Layers by default) and click Properties.
2. Click the Coordinate System tab.
3. Click Predefined > Geographic Coordinate Systems > World > WGS 1984, then click OK.

Design at the ArcGIS Online scales

Users of your map will see it at the scales used by ArcGIS Online services, so you should only design your map at those scales. But how do you know what those scales are?

You can load the ArcGIS Online scales into the ArcMap scale drop-down list by doing the following:

1. Copy this text file arcgis_online_scales.txt to a location that you can easily remember. (The link here is provided for simplicity. The file is originally installed in the Help directory of your ArcGIS Server instance. Example: C:\Inetpub\wwwroot\ArcGIS\Manager\Help\arcgis_online_scales.txt)
2. Open ArcMap and add some data.
3. Click the dropdown list of scales and click Customize This List.
4. Click Load.
5. Browse to the arcgis_online_scales.txt file mentioned in Step 1 and click Open.
6. Click OK to apply your changes and dismiss the dialog. You should now be able to see all of the ArcGIS Online scales and easily jump between them using the dropdown.

You only need to design your map to look good at the scales at which it will be cached. If you do not plan on caching your map at the larger scales, you do not need to do any design work at those scales.

Set scale ranges on your layers so that just the right amount of data and labels are visible at each scale, symbolized appropriately. When setting your scale ranges, avoid toggling layers on and off at or near the scales at which you are designing.

You may need to make copies of your layers so that you can symbolize them differently at various scales. The ArcMap table of contents can contain multiple copies of a layer, each with its own symbology and scale ranges. To copy a layer, right-click it in the ArcMap table of contents and click Copy. Then right-click the data frame name and click Paste Layer(s).

Publish the map as a service

After you've finished authoring your map document (.mxd), you need to publish it as an ArcGIS Server map service before you can use it in your application. One of the easiest ways to do this is to right-click the map document in ArcCatalog and click Publish to ArcGIS Server.

Learn more about publishing a GIS resource to the server.

Create a map cache

One of the reasons ArcGIS Online services are so fast is that they use server-side map caching, meaning that predrawn images of the map are stored on the server so that you can quickly request them through a URL. With ArcGIS Server, you can create a similar cache for your map. Creating a map cache is recommended for optimum performance.

The Map caches section contains much detail about planning, creating, and updating map caches. There are several ways to create a cache, but the following steps are essential:

1. Right-click the service in ArcCatalog and click Service Properties.
2. Click the Caching tab and choose to draw the map "Using tiles from a cache that you will define below".
3. Click "Load tiling scheme from" and choose ArcGIS Online from the drop-down list.
4. If necessary, change the Cache directory.
5. Click Create Tiles. The caching tool appears with many values already filled in.
6. Uncheck any scales for which you do not want to create the cache. If your map covers a big area and will not be viewed at large (zoomed-in) scales, you should uncheck the large scales.
7. Set the update mode to Recreate All Tiles and click OK. The tool then creates the tiles.

Depending on how big your map is and the scales you've selected, it could take a long time to create all of the tiles. See Planning a map cache to learn about factors that influence cache creation time.

Once you've finished creating the cache, you're ready to use your map with ArcGIS Online services. See Developing with ArcGIS Server: An Overview to learn how you can develop JavaScript and Web ADF applications that overlay your maps with ArcGIS Online services.