Creating a map with multiple background layers

You can use multiple background layers in a map chart. This enables you to create layered base maps for your map chart data.

Some WMS sources include layers with transparency. With these sources, you can overlay the WMS background layer on top of a base map or other layers. Images can also be placed over other background layers. This enables you to create more complex base maps for your data.

In this map example, a custom TMS is used in a background layer. A WMS background layer is placed on top, using a WMS endpoint from the National Ocean and Atmospheric Administration. The WMS layer shows weather radar data.

Dataset

This example uses a single table for data, Cities, with an external TMS and WMS data from external sources.

Cities

Cities

Cities
Albany, New York
Annapolis, Maryland
Atlanta, Georgia
Augusta, Maine
Austin, Texas
Baton Rouge, Louisiana
Bismarck, North Dakota
Boise, Idaho
Boston, Massachusetts
Carson City, Nevada
Charleston, West Virginia
Cheyenne, Wyoming
Columbia, South Carolina
Columbus, Ohio
Concord, New Hampshire
Denver, Colorado
Des Moines, Iowa
Dover, Delaware
Frankfort, Kentucky
Harrisburg, Pennsylvania
Hartford, Connecticut
Helena, Montana
Honolulu, Hawaii
Indianapolis, Indiana
Jackson, Mississippi
Jefferson City, Missouri
Juneau, Alaska
Lansing, Michigan
Lincoln, Nebraska
Little Rock, Arkansas
Madison, Wisconsin
Montgomery, Alabama
Montpelier, Vermont
Nashville, Tennessee
Oklahoma City, Oklahoma
Olympia, Washington
Phoenix, Arizona
Pierre, South Dakota
Providence, Rhode Island
Raleigh, North Carolina
Richmond, Virginia
Sacramento, California
Saint Paul, Minnesota
Salem, Oregon
Salt Lake City, Utah
Santa Fe, New Mexico
Springfield, Illinois
Tallahassee, Florida
Topeka, Kansas
Trenton, New Jersey

How I built this

Before you start

Before you start, the following origins must be added to the allowlist for the Content Security Policy. This is done in the Administration activity center by a tenant administrator.

For more information about adding Content Security Policy entries, see Creating a CSP entry.

Building the map

Do the following:

1. Add the table Cities to your app. You can copy and paste the table using manual entry.
2. In a sheet, add a map chart.
3. In Map settings, set Base map to None.

4. Add a background layer and do the following:

   • In Data, do the following:

     • For Format, select TMS.
     • For URL, enter https://a.tile.openstreetmap.org/${z}/${x}/${y}.png.
     • For Attribution, enter © OpenStreetMap contributors.

   • In Options > General, do the following: 

     • Set Show legend to None.

   • In Options > Presentation, do the following:

     • Set Opacity to 0.5.

5. Add a background layer and do the following:

   • For Label, enter Weather Radar Base Reflectivity Mosaics.

   • For Format, select WMS and click WMS setup. Do the following:
     • For WMS server URL, enter https://nowcoast.noaa.gov/geoserver/observations/weather_radar/ows.
     • For Version, select 1.3.0.
     • Click Load WMS.
     • In Step 2 (Settings), set the following settings:
       • Set CRS to EPSG:3857.
       • Turn on the Transparent setting.
       • Select all options under Weather Radar Base Reflectivity Mosaics.
     • Click Save.
   • For Attribution, enter NWS, DOD, NOAA, and nowCOAST.

6. Add a point layer and do the following:

   • In Data, add Cities as the dimension.
   • In Location, do the following:
     • Set Scope for locations to Custom.
     • Set Country to 'USA'.
   • In Colors, set Colors to Custom and set Color to f93f17.
   • In Size & Shape, set Bubble size to 9.