KNOWLEDGE BASE

Map Tiles from WMS Server Appear Stretched


Published: 21 Aug 2013
Last Modified Date: 27 Aug 2015

Issue

When using a Web Map Service (WMS) map in Tableau Desktop, the map tiles appear distorted or stretched.

Environment

  • Tableau Desktop
  • Web Map Service (WMS)

Resolution

Tableau Desktop maps use the EPSG 3857 (Web Mercator) projection while WMS servers use the EPSG 4326 or EPSG 4269 projections. The EPSG 4326 projections may look distorted, particularly at northern latitudes.

To determine if distortion is an expected:
  1. Connect to another WMS server such as http://www2.demis.nl/WMS/wms.asp?WMS=WorldMap and compare the distortion between the two maps.
  2. Connect to the WMS server in a program such as QGIS and compare the distortion there to the distortion in Tableau Desktop.
Depending on the features of the WMS server, it may be possible to use a .tms file to use a Web Mercator projection instead. For more information, see Connecting to the Tableau Map Service.

Cause

Tableau Desktop supports WMS server maps that adhere to:
  • WMS 1.1.1 standards
  • EPSG:4326 and EPSG:4269

Additional Information

QGIS
  • Tableau Desktop will not alter map tiles received from a WMS Server.
  • Fiddler trace can reveal the WMS standard and EPSG the WMS server is using. Verify the following information is in the XML found in the Fiddler trace:
    • SRS = EPSG:4326 or EPSG:4269
    • WMT_MS_Capabilities [ version  1.1.1 ]
  • You can use Fiddler to ensure the map tiles retrieved from the WMS Server appear without distortion:
    1. Open HTTP trace that recorded traffic from WMS server
    2. Right-click on any image retrieved
    3. Select Save
    4. Select ...and Open as Local File
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