Creating and applying a condition

In the Object Analyst Condition Builder window, you can define a condition for rule-based classification. The condition can be based on up to two attributes. That is, you can construct a maximum of two conditions per rule. Both conditions can be based on a single attribute, or on two different attributes linked by a logical AND or OR operator.

For example, to specify a two-part condition where i) classification occurs on an area attribute with a value of greater than 100,800 and ii) less than 109,800 for the same area attribute, specify the condition as follows.

To set up the first part of the condition for the preceding example:

Under Attribute, click Area, under Attribute values, click 100800, under Condition, click Greater Than, and then click Add.

And then to set up the second part of the condition:

Under Attribute, click Area, under Attribute values, click 109800, and then under Condition, click Less Than, click AND, and then click Add.

The preceding is only an example. If you need only a single-part condition, you can set it up as such.

A condition can be a maximum of two parts, however.

To create and apply a condition

In the Object Analyst window, set up the rule-based classification, and then under Parameters, select the Specify condition check box, and then click Build Condition.
The Object Analyst Condition Builder window appears.
Under Attribute, click the attribute of the vector layer for which you want to create a condition.
The Attribute values list is updated with the available values.
Under Attribute values, click the value you want.
To view all the available values, click Entire List.

Note: Because the entire list of attributes can sometimes be extensive, loading it may degrade system performance during processing.
Under Condition, click the operator you want to use, and then click Add.
The condition appears under Conditions table.
Repeat steps 2 to 5, as applicable, for each attribute for which you want to create a condition, and then click Close to return to setting up Rule-based Classification.