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Problem: WMS legend items do not draw or do not draw as expected

Description

Most layers in ArcMap contain legend items displaying the layers symbology. These legend items are visible in the Table of Contents and can also be included in the legend of a map layout.

1. In some cases legend items for WMS layers do not draw in the Table of Contents and the WMS layers are not listed among the Map Layers in the Legend Wizard.

2. In other cases, the WMS layer legend items in the Table of Contents do not draw as expected. For example, the legend item graphic appears 'cut off'.

** The feature addressed in this article is only available in ArcGIS 9.0 Service Pack 2, which can be downloaded through the link in Related Information, below. **

Cause

1. Not all WMS services support legends. You will not be able to view legend items in the Table Of Contents or create legends within a page layout unless the WMS service supports legends.

For WMS services that support legends you will not see the legend items in the Table Of Contents by default. These are hidden. This is because requesting a legend for each specific sublayer in a WMS services requires sending a specific request to the WMS service. Doing this for all the layers in a service may result in poor performance.

2. In some cases, the legend returned by the WMS server are of such size that they do not fit well into the Table of Contents' Patch Size specified by ArcMap.

In addition, WMS legends may be such that ArcMap cannot display the legend at all. For example, a WMS layer legend may contain multiple symbols or is of a large enough size that ArcMap can not draw it in the Table of Contents. In these cases, the Legend Wizard will exclude these WMS layers from the Map Layer list.

Solution or Workaround

The causes listed above have corresponding solutions given below:

  1. There is no workaround when the WMS server does not support legends. Information concerning legend support is found in the capabilities file of the WMS service.
    <a href='http://support.esri.com/en/knowledgebase/techarticles/detail/27948' target='_blank'>How To: View the WMS service capabilities</a>

    For WMS services that support legends, ArcMap makes displaying the legend items an "on demand" option. That is, the user explicitly requests a legend item by clicking the expansion control next to a layer in the service.
    [O-Image] legend_collapse


    The legend item is now available.
    [O-Image] legend_expand
  2. Adjusting the Patch Size for the Table of Contents may help. To adjust the Patch Size:

    A. Select Tools from the Main Menu and click Options
    B. Choose the Table of Contents Tab
    C. Adjust the Patch Size Width and Height accordingly. Try increasing the size.

    The legend size specified by the WMS server may be too large for ArcMap to accomodate. In this case ArcMap cannot draw the legend. This is a known limitation.

Related Information