With ArcGIS AllSource, you can use Open Geospatial Consortium (OGC) services that are available on the web, such as WMS and WMTS services.
For more information regarding OGC WMS specifications, see the OGC website at www.opengeospatial.org/standards.
The OGC Web Map Service (WMS) is a map portrayal service used to publish a collection of map layers to embed in your interactive web maps. The WMS specification expresses the map contents as map layers using XML. The primary use of the WMS is to openly serve interactive map images on the internet.
WMS client support in ArcGIS allows you to access these services over the internet and add a WMS layer to your maps.
View WMS services in the Contents pane
After connecting to a WMS server, a WMS service connection is shown in the Server folder in the Catalog pane. You can add the entire service to your map. The first 20 layers are turned on automatically since a WMS service doesn't define which of its layers are visible. This allows you to view several layers at once without having to turn on or off a large number of individual layers. When you initially zoom in on WMS services, you won't necessarily see more detail unless the layers providing more detailed data are in those first 20 layers.
When added to ArcGIS AllSource, the WMS service layer's entry in the Contents pane is collapsed to save space, but you can expand it and its groups to see the individual layers it contains.
A WMS service layer is made up of three entries arranged hierarchically in the Contents pane. At the top is the name of the WMS service, which contains all the WMS map layers. The next level is WMS group layers, whose only function is to organize WMS sublayers into related groups. There is at least one WMS group layer, but there can be any number of WMS group layers (and even nested groups within groups). WMS group layers do not contain any map layers; it is the third group, WMS sublayers, that actually contains the map layers.
WMS group layers and sublayers are always part of a WMS service. When you add individual WMS sublayers, one WMS service entry in the Contents pane is created for each sublayer added. The more WMS service sublayers there are in the map or scene, the more requests to the server are sent, which can affect performance. You can use the Layer Properties dialog box to add or remove WMS sublayers of an existing WMS map layer in ArcGIS AllSource. When adding a small list of WMS sublayers, a flat list of layers with no group layers is added to the Contents pane.
WMS service sublayer legends
When a WMS service includes legend information, you can view the WMS sublayer's symbology in the Contents pane by expanding a layer in the service. The legends for the layers in WMS services are hidden by default in the Contents pane, since accessing a legend for one layer in a WMS service requires sending a request to the server. For each additional layer, an additional request is sent to the server. This can affect how quickly the map and legend are displayed.
Some WMS services do not include legend information about the symbols used by the layers in the service. When legend information is not available, no symbology is shown for the layers in the Contents pane. These layers are listed in the Contents pane, but they cannot be expanded.
The size of WMS legends can vary. With WMS services, the legends for layers are transmitted over the internet as one image with all the symbols. If the layer contains multiple legend styles, you can choose which style to use as well as the size of the requested style.
Change the style of a WMS service sublayer
The rendering of a WMS sublayer is determined by a style. The WMS specification allows a WMS layer to contain a list of styles in which the layer can be rendered. The WMS server may make the style symbology available to the user as a legend. If the WMS service supports legends, you can use the styles to preview a WMS service sublayer's legend. If the sublayer has multiple styles listed in the service capabilities, you can use the Styles tab to choose the style you want.
- Choose a WMS sublayer in the Contents pane.
- On the WMS Sublayer tab, in the Drawing group, click the Symbology drop-down menu
. In the Symbology gallery, click the style you want
to show.The Symbology pane appears, displaying the current style information.
- Optionally, change the legend height, legend width, and the URL defining the style.
Change the display of a WMS service layer
On the WMS layer properties dialog box, the Layers tab displays all the members of the WMS service. When the Select the sublayers to include option is selected, you can move the sublayers you want to display from the List of all layers list to the Ordered sublayers to include list. Information provided by the WMS server for each WMS layer is displayed when you hover over a WMS layer in one of the lists. You can change the layer drawing order by moving sublayers up or down in the list.
The Display tab allows you to change the properties of the WMS service. For example, you can change the background color or make the background color transparent. You can also define the image format type that you want to request from the WMS service. If a WMS service layer has transparency that you want to blend with other layers in the map, the image format of the layer requested from the WMS service must be PNG32.
Some WMS servers support additional map parameters that are specific to the WMS server itself. You can add and remove these parameters in the Custom request parameters list. ArcGIS AllSource cannot validate the settings to ensure that the service honors these map parameters.
Note:
The following requirements apply to any custom request parameter name specified on the layer:
- It must not conflict with another parameter specified when the service connection was made.
- It must not conflict with reserved keywords. These include: service, version, request, crs, bbox, width, height, layers, styles, exceptions, format, bgcolor, transparent, query_layers, info_format, feature_count, i, j, x, y, srs, layer and wmtver.
For other layer types, you can change common properties of the layer such as transparency and visibility range, or swipe the layer using the ribbon contextual tab.
- Choose a WMS layer in the Contents pane.
- On the WMS Layer tab, use the tools to adjust the appearance of the layer as needed.
Get information about a WMS service layer
On the WMS layer properties dialog box, the Source tab displays information such as the map extent, data (service) type, URL, service name, and default coordinate system of the service.
Note:
The layer name shown may not be the same as what is in the Contents pane and on the General tab. This is because the text used for the layer name on the Source tab is taken from the <Name> tag in the WMS service capabilities file, which is the file used to describe the service. However, ArcGIS AllSource uses the more descriptive <Title> tag from the capabilities file to populate the layer name for the Contents pane and the General tab.
The Metadata tab displays information about the layer, derived from the service. The following table outlines how these service properties appear in the dialog box.
| WMS property | Corresponding metadata field | Description |
|---|---|---|
Title | Title | The title of the WMS service |
Keywords | Tags | A list of keywords or keyword phrases describing the WMS service that aid in catalog searching |
Abstract | Description | A narrative description that provides additional information about the WMS service |
Access Constraints | Use Limitations | Text describing the restrictions and legal prerequisites for accessing and using the WMS service |
Caution:
The metadata on a WMS sublayer is read-only regardless of the setting of this menu. Information entered using the Layer has its own metadata will not be persisted.
You can get information about each WMS sublayer from the service layer properties Layers tab. Choose Select the sublayers to include and hover in the List of all layers section or the Ordered sublayer to include list of the WMS service sublayers. You can view the capabilities of the sublayer: whether the layer supports Identify, whether a legend is available for the sublayer, the default coordinate system, and a list of server-supported coordinate systems for this particular sublayer.
Identify features from a WMS layer
According to the OGC WMS specification, WMS services are not required to support <GetFeatureInfo>, which is the request ArcGIS AllSource sends to the server when you query features in a WMS service. If the service supports identifying, its sublayers are listed in the pop-up window. If they aren't listed, you won't be able to identify features from that WMS service.
Identify tolerance levels are determined by the WMS server, not ArcGIS AllSource. When identifying WMS point features, you may have to click multiple times to get close enough to the feature to register a positive result.
Identifying features is the only querying task you can perform on WMS data, although the format of information you receive can vary depending on the server. ArcGIS AllSource displays what is returned by the server inside a Microsoft Edge control embedded in the Identify window. The result of an Identify query may be provided as field-value pairs, HTML, or images.
However, not all WMS services support identifying. In addition, no WMS services support the following querying operations:
- Show popup
- Selecting features
- Performing geoprocessing
WMS service layers and coordinate systems
In this version of ArcGIS AllSource, only the default coordinate system is used, and you cannot change it. However, if you change the coordinate system of the map or scene, the map's coordinate system is requested.