Changing the map projection in ArcGIS Online

[JenniferWrightsell-Hughes]

As a map author, you may have noticed that web maps you create in ArcGIS Online Map Viewer are displayed by default in the Web Mercator map projection. This is because all basemaps in the default basemap gallery in ArcGIS Online are in Web Mercator.

But what if you want to use a map projection other than Web Mercator for your map?

Why change the projection?

All map projections distort the earth in some way, and your map may require a different projection, depending on its focus. For example, the Web Mercator projection greatly distorts area, which is particularly problematic when displaying Canada’s northern regions. This is apparent when you compare the following maps:

While both maps are displayed at similar scales, each one uses a different map projection: Web Mercator (shown on the left) and Lambert Conformal Conic (shown on the right). You can see that Lambert Conformal Conic is a more appropriate projection for a map of Canada because area is not distorted the way it is with Web Mercator.

How to change the projection

In Map Viewer, the projection of the basemap defines the projection of the map. Therefore, the way you change the projection of the map is by adding a layer in the desired projection as a basemap layer. The key to this workflow is a simple, yet powerful option called Use as basemap, which tells Map Viewer to use the map projection of the current layer to display the map.

To learn how to change the projection, watch the following short video or follow the steps outlined below.

1. Start a new map in Map Viewer.

2. On the Contents (dark) toolbar, click Add.

3. Do one of the following to find a layer in the desired projection to add to the map:

• Click Browse layers and search for the layer you want.
• Click Add layer from URL and enter the URL of a layer from the web, such as an ArcGIS Server web service.

4. Do one of the following to add the layer as a basemap:

• If you browsed to the layer, click its name and click Use as basemap.
• If you entered a URL, turn on the Use as basemap toggle button and click Use as basemap.

The layer is added as a new basemap for the map and the map is now displayed in the projection of the new basemap.

As you continue to build your map, any layers you add will automatically be displayed in the same projection as the basemap. This means that any layers in projections other than that of the new basemap will be reprojected on the fly in Map Viewer. If you’re concerned about browser load or speed, you might want to ensure that additional layers are in the same projection before you add them.

Learn more

To learn more about map projections and how to work with them, see the following resources:

• Documentation
• Tutorial
• Blog article

[MarkGambordella]

I do not see this function in our MapViewer or MapViewer Classic.  Is this a new release that shows the function to use as basemap?  I need to record the Lat,Long in USFeet for our editable feature.  Is there another way to add the projection to teh map or a script to enter as an expression to code for the change from the default projection.  thank you

[JenniferWrightsell-Hughes]

Hi - It's possible that you are trying to add a layer type that's not supported as a basemap. Supported layer types are imagery, map image, tile, vector tile, WMS OGC, WMTS OGC, Bing, and OpenStreetMap.

[MarkGambordella]

I was trying the a feature service from our REST server.

I would like to create a layer or some how write a to calucate x y in NAD 1983 StatePlane Louisiana South FIPS 1702 (US Feet) , Lambert Conformal Conic.  

This would be helpful when we are adding new data points to an older layer that already has x y data in a table recorded as the projection above.  What is teh best way to go about this.

We are doing the editing of the layer now in AGo rather than ArcPro so field workers can enter new data points.  thanks

[JenniferWrightsell-Hughes]

Hi @MarkGambordella - I may not be understanding your use case correctly, but I think you would have to use ArcGIS Pro to create and publish your feature service in the coordinate system you want. Then you could bring it into ArcGIS Online with a basemap in the same coordinate system or just enable it for offline use and let field workers download it in Field Maps and sync their edits back to the layer. Hope this helps!

[MarkGambordella]

When I am in Pro.  I have only one layer in the map.  that layer is set to NAD 1983 StatePlane Louisiana South FIPS 1702 (US Feet). but the basemap that it is on is web Mercator.  when i publish the map service, feature service to AGO it stays as Web Mercator and returns x,y based off of that coord sys.  Our data field in the attribute table for this layer needs to the new data points match the old points which have x,y coord stored in NAD 1983 StatePlane Louisiana South.  I tried writing a script within the form for the editable feature for x, y but the coordinated will not match up with what we have been populating when the feature was in ArcPro.  WE are sitting up an Address issuance tool.  the original add on tool was created in ArcMap.  But our organization is no longer using Map and has switched to PRO.  I thought it might be easier to setup an editable layer in AGO for adding new addresses.  but i need for the x,y to stay the same as previously issued. thanks

Do i need to publish the web service as a WMS in addition to a Feature Service.

10001: Layer's data source has a different projection <value> than the map's projection

[JenniferWrightsell-Hughes]

Hi @MarkGambordella - 

It sounds like you may be trying to share data in a specific coordinate system but ArcGIS is reprojecting the data into Web Mercator as it shares it.

If I've understood the problem correctly, I would say no, you shouldn't have to publish a WMS. It should be possible to share a feature service in whatever coordinate system you want. I suggest that you ensure that your map (not just the layer) is set to NAD 1983 StatePlane Louisiana South FIPS 1702 (US Feet) before trying to publish. That might solve the problem. If it doesn't work, you can try publishing via the Share as Web Layer tool instead (on the ribbon, click the Share tab. In the Share As group, click Web Layer).

If you are still having problems, I would recommend that you contact Esri Support for assistance.