Unique value rendering

Unique value rendering can be used to symbolize layers that allow configuration of symbology. For more information on the different layer types and their capabilities, see Layer types.

About unique values

"Unique values" refers to a set of values, each of which is unique for a particular field or attribute within a given set of data. For example, if a set of data has a field called STATE_NAME that has values { Washington, Washington, Washington, Montana, Connecticut, Connecticut, Connecticut, Florida, Oklahoma, Oklahoma }, the set { Washington, Montana, Florida, Oklahoma } would be a valid set of unique values. Notice that, within the set of unique values, no values are repeated. A unique value renderer maps a set of unique values to a set of symbols.

As an example, suppose you have a buildings layer with an attribute that specifies how each building is zoned. To symbolize the buildings differently based on the zoning of each, you could define a unique value renderer that specifies a yellow symbol for residential, purple for industrial, blue for commercial, and so on, for every zoning classification.

Configuring a unique values renderer

The ArcGIS Viewer for Silverlight makes it simple to apply unique value rendering to a layer. To do so, complete the following steps:

  1. Choose the desired layer on the Configure Layers panel.
  2. Right-click the layer and click Configure. Alternatively, click the Configure button at the bottom of the panel:
    Configure layer
  3. On the Configuring panel that appears, click Symbology to view the configuration options:
    Symbology menu
  4. You can configure the unique values renderer as follows:
    • Changing the attribute—To change the field on which the symbols are based, expand the Attribute drop-down menu and choose the desired field:
      Attribute drop-down menu expanded
    • Changing the color scheme—You can apply a predefined color scheme to the renderer by choosing the desired gradient from the Color Scheme menu:
      Color Scheme menu

      The color scheme is applied differently depending on the geometry type of the selected layer as follows:

      • For a polygon layer, the colors are applied to the fill colors of the polygons.
      • For a line layer, the colors are applied to the colors of the lines.
      • For a point layer, the color is applied to the selected point symbol. Colors are not applied to picture symbols.
    • Selecting a value's symbol—To specify the symbol for one value, click the symbol to the left, or the down arrow to the right, of the value, then choose the desired symbol from the symbol picker:
      Symbol picker dialog box
    • Modifying a value's symbol—To modify the symbol used by a value, select the value from the right side of the dialog box, then use the controls in the Current Symbol section of the dialog box to adjust the symbol's size, color, and transparency.

      The size and color controls that are enabled vary depending on the geometry type of the selected layer. For further information about specifying a symbol's size and color, see Single symbol rendering. The number of transparency sliders enabled also varies depending on the geometry type of the selected layer. For line and point layers, only one slider is enabled. When this is the case, the enabled slider determines the transparency of the entire symbol. For polygon layers, both sliders are enabled. The top slider determines the transparency of the symbol's fill, while the bottom slider determines the transparency of the symbol's border.

    • Adding or removing values—While the Viewer automatically determines the unique values that are present in a layer, you also can manually add or remove values. You might want to add values that are not present in the data, for instance, if you are monitoring a set of data that you know will increase. Alternatively, you might want to remove values to prevent features with certain values from being displayed on the map. To add a value, type the desired value into the Edit Values text box and click the Add button. To remove a value, choose the value from the right side of the dialog box and click the Remove button.