Operating Node Reduction By Flow rules

Prerequisite:

Before configuring a Node Reduction By Flow rule, you must check that the node schematic feature class required for the rule execution already exists in the schematic dataset and is associated with the schematic diagram template on which the rule is going to be specified.

Before learning more about the Node Reduction By Flow rule configuration, there are also some terms specific to this rule you have to know:

• The reduced nodes are nodes that will not be graphically contained anymore in the final resulting diagram.
• A source node is a node from which all connected links start.
• A sink node is a node at which all connected links end.
• The links that are created to preserve the logical flow are super spans.

The Node Reduction By Flow rule allows you to generate schematic diagrams after all or some nodes implemented by a given schematic feature class have been removed and after the links that connected these removed nodes are reconnected so the logical flow of the network is preserved.

Note:

Even if there is no flow on your network, the Node Reduction By Flow rule can be applied. In this case, the rule works with the links' orientation—that is, with the From and To nodes that defined each link.

The reduced nodes are nodes implemented by a given schematic feature class that will not be contained in the final resulting diagram. You can choose to reduce either all the nodes implemented by that specified node schematic feature class or only some of them that have been filtered out according to the following:

• A SQL filter that works on the real feature class/object table associated with that node schematic feature class
• Any particular attribute on the links incident to the node candidate for reduction, or any particular field expected on the real feature classes associated with the link schematic feature classes that implement the links incident to the node candidate for reduction

For the specific source and sink nodes, you can also configure the rule so such nodes are also reduced or not reduced.

The steps below focus on the configuration of the Node Reduction By Flow rule properties page that displays when clicking the Rule Properties button on the Rules tab toolbar while such a Node Reduction By Flow rule has already been added to that tab. To learn about how to add any new rule item on the Rules tab and display the Rule Properties page, read the Specifying a schematic rule on a schematic diagram template topic.

For a Node Reduction By Flow rule that has just been added on the Rules tab, clicking the Rule Properties button on the Rules tab toolbar opens the Rule Properties dialog box as follows:

1. Type a description for the rule in the Description field.

   This description string will display on the Rules tab for the related rule item and will also display during schematic diagram generations and updates to inform users that the rule is being executed.

2. Select the name of the node schematic feature class to be reduced from the Select the node schematic feature class to reduce drop-down list.

   Only the node schematic feature classes that are associated with the schematic diagram template are available from this drop-down list.

   At this step of the rule configuration, all the schematic nodes implemented by that selected node schematic feature class are configured to be reduced.

3. Check the Keep vertices check box if you want the vertices displayed along the links incident to the reduced node to be kept after nodes reduction.

   When this check box is checked, a vertex is also displayed at the reduced node location.

   Note:

   This option is interesting for diagrams that aren't laid out, that schematic features display at their geographic coordinates, and for which the schematic links display with initial vertices. For diagrams that are laid out and updated after a route node reduction rule has been configured, no vertex is added at the reduced node location to preserve the saved layout.

4. If you want to specify a SQL filter on the specified node schematic feature class so only certain ones are reduced, do the following:
   1. Click the Edit button at the right of the SQL Filter on associated feature/object class area.

      The SQL Query dialog box opens.

   2. Build the SQL expression you want.

      The filtering operates on the fields stored on the feature class or object class associated with the specified node schematic feature class.

   3. Click OK.

      The SQL Query dialog box closes, and the SQL filter you have just specified automatically displays in the SQL Filter on associated feature/object class area.

   The specified SQL filter will then be used to determine the subset of schematic nodes reduction candidate. Those that don't verify the SQL filter will not be reduced during the rule execution.

5. To determine the nodes to reduce, you can also specify a constraint based on a schematic attribute configured on the schematic links incident to the nodes reduction candidate or on a field stored on the real features/objects that are associated with the schematic links incident to the nodes reduction candidate. This constraint must be specified on the Connected link attribute section:
   1. Check the Use attribute name check box.
   2. Type the name of the schematic attribute or field that will be used.

      For each schematic link that connects to a node reduction candidate, the rule first searches for a schematic attribute with this name on the schematic link. If no schematic attribute with this name is detected, the rule searches for a field with the same name on the GIS feature associated with the schematic link. The node will then be reduced only if the detected attributes or fields exist with the same value for all its connected links.

6. From the Reduction options area, specify whether the particular source and sink nodes will also be reduced during the rule execution or not.
   1. Check the Reduce if the node schematic feature is a source check box if you want to reduce nodes that are implemented by the specified node schematic feature class even when they are source nodes.

      When this box is unchecked, the source nodes implemented by that specified node schematic feature class are not reduced.

   2. Check the Reduce if the node schematic feature is a sink check box if you want to reduce nodes that are implemented by the specified node schematic feature class even when they are sink nodes.

      When this box is unchecked, the sink nodes implemented by that specified node schematic feature class are not reduced.

7. On the Reduced link schematic feature class section, specify whether all or only some of the schematic nodes reduction candidates will be reduced, depending on the number of their connected links. For each reduced node, one of its connected links is reduced, and other links are created to preserve the logical flow. The reduced options allow you to specify the link schematic feature class that will be used to implement these new links:
   • Choose the From link schematic feature class option if you want the links created to keep the logical flow to be implemented by the same schematic feature class as the link schematic feature classes implementing the links, which start from the reduced node.
   • Choose the To link schematic feature class option if you want the links created to keep the logical flow to be implemented by the same schematic feature class as the link schematic feature classes implementing the incident links, which end at the reduced node.
   • Choose the Other option if you want all new links created to keep the logical flow to be implemented by a given link schematic feature class independently to the schematic feature classes that implement the incident links related to the reduced node. In this case, select the name of the desired link schematic feature class from the drop-down list that displays on the right of the Other option. All the link schematic feature classes that are associated with the diagram template are available on the list.
8. Click OK to close the Rule Properties dialog box.

• Node Reduction By Flow rule sample results