About Basing Native Feature Layer Properties on Layer Attribute Fields
After loading a feature layer with attribute fields, you can apply different properties such as line color or cylinder height, based on the attribute field values of the objects.
Let's take as an example a polygon’s layer that covers the terrain with country boundaries. With the help of this feature, it is possible for TerraExplorer to color in red only the boundaries of countries with a population of more than 10 million people.
Note that you can base properties on field attributes, only if the feature layers are loaded with attribute fields, such as "Country Population". If the layer does not contain attribute fields, or in the loading phase, you did not select any attribute field to load, you cannot take advantage of this feature.
See “Loading Layer Attribute Fields” in this chapter to learn how to add the attribute field information in the loading phase.
When basing a property field on an attribute field, you have to establish the property you want to set, and the attribute field on which to base your setting. In our example, the property is the country boundary's Line Color, and the attribute field is "Country Population".
Attribute Fields
Properties can be based on three types of attribute fields:
|
Description |
Type of Storage /Example |
|
Textual attribute field types |
e.g., Country Name. |
|
Integer attribute field types |
Stores whole numbers without any decimals. e.g., State Population. |
|
Double attribute field types |
Stores real numbers having a double precision floating point. e.g., Average Income. |
The field attribute type determines how the property is based on the value of the field attribute.
§ When the attribute field is numeric - integer of double - it is possible to group attribute field values in ranges. For example, you can set the boundary line color to red for countries with a population between 1,000,000 and 2,000,000 and to green for countries with a population between 2,000,001 and 3,000,000.
§ When a property is based on a numeric field attribute, it is also possible to use the >< =><= operators. For example, you can set the boundary line color to orange for all countries with a population larger (>) than 1,000,000.
Properties
There are four types of properties that can be set based on attribute fields:
§ Color properties such as line color and fill color.
See “Basing Color Properties on Attribute Fields” in this chapter for further information.
§ Numeric properties such as cylinder height or text label altitude.
See “Basing Numeric Style Properties on Attribute Fields” in this chapter for further information.
§ The text content of text labels, tooltips and other text elements.
See “Basing Text Content on Attribute Fields” in this chapter for further information.
§ Dropdown lists properties such as font size or text underline.
See “Basing Dropdown List Properties on Attribute Fields” in this chapter for further information.