Geo - Linear Dispatch layout algorithm properties

When the Geo - Linear Dispatch schematic layout algorithm is chosen in the Layouts Task drop-down list, clicking the Layout Algorithm Properties button on the Schematic Editor toolbar opens its associated properties dialog box as follows:

The parameter values are either those specified by default by ArcGIS Schematics or those specifically set as the default for the schematic diagram template related to the active diagram using the Schematic Dataset Editor Layout Task tab for this schematic diagram template.

Three types of schematic nodes can be moved during Geo - Linear Dispatch schematic layout algorithm execution:

• Those that have two connected schematic links. They are represented by a red circle in figure 1.1.
• The leaf schematic nodes (nodes with one connected link) that are moved when the Expand leaves and/or Move leaves check boxes are checked. They are displayed with a green circle in figure 1.1.
• The schematic nodes with three connections connecting at least one leaf node, the schematic nodes with four or more connections for which two connected links connect nonleaf nodes, and all the other connected links that connect leaf nodes. These schematic nodes are moved when the Move leaves check box is checked. This type of node is represented by a pink circle in figure 1.1.

All the other schematic nodes (such as those represented by a black square in figure 1.1) are not moved by the algorithm.

Nodes placement options

The Nodes placement options determine the way the nodes are moved.

• Choose the Equal distance option when moving all the nodes with two connected links so the distances between them and their two connected nodes are equal. This is the default option unless another option is specified for the diagram template related to the active diagram.

  The figures below show the Equal distance option. The schematic nodes with three or more connected links (pink symbols) and those with one connected link (leaf nodes represented by green symbols) are not moved. Only the schematic nodes with two connections (red symbols) are moved. The d1, d2, and d3 distances between each moved node and its connected link's extremity are equal. Figures 2.2 and 2.4 show the results obtained with the Equal distance option when the Preserve path box is unchecked (figure 2.2) or checked (figure 2.4).

• Choosing the User defined distance option and typing a value for the Minimum shift parameter determines the minimum distance that will separate the schematic nodes with two connected links from the link extremity after algorithm execution. The distance unit depends on the Absolute units check box. By default, the Minimum shift parameter value is 2 unless another value is specified for the diagram template related to the active diagram. Note that when the Minimum shift parameter value is too large, the nodes with two connections are moved so the distances between each moved node and its link extremities are equal along the path defined by its two connected links.

  The figures below show the User defined distance option with the Absolute units check box unchecked. Figure 3.2 shows the result obtained when Minimum shift = 3. Only one of the nodes with two connections, highlighted in the red circle, has been moved. The other nodes with two connections have not been moved, because the distances between them and their link extremities are already three (or more).

• If you choose the Iterative distance option, the Linear Dispatch algorithm slightly moves all nodes with two connections according to the Number of iterations and Maximum shift parameter values.

  The Maximum shift parameter specifies the maximum distance those nodes can be spaced from the nodes to which they connect. The distance units depends on the Absolute units check box. When this distance is reached, nodes are no longer moved. By default, the Maximum shift parameter value is 2 unless another value is specified for the diagram template related to the active diagram. The Number of iterations parameter determines the number of Linear Dispatch iterations that are executed before the final result is shown. By default, the Number of iterations parameter value is 5.

  The figures below show the results obtained with the Iterative distance option, with Maximum shift = 5, Number of iterations = 100, and the Absolute units check box unchecked. Figure 4.1 represents the initial schematic diagram. Figure 4.2 shows the result after the first execution of the Linear Dispatch algorithm. The black crosses on the links show the initial position for the moved nodes. As shown in this figure, Node 2's displacement is greater than that of Nodes 1 and 3. Figure 4.3 shows the result when the Linear Dispatch algorithm is executed a second time. As the black cross near Node 3 shows, the maximum shift distance for this node is nearly reached. Figure 4.4 shows the diagram obtained after a third execution of the Linear Dispatch algorithm.

Advanced parameters

The Advanced parameters allow you to refine the Linear Dispatch result.

• Check the Preserve path check box if you want the path for the connected links related to the moved nodes to be preserved during algorithm execution. In this case, the initial intermediate points displayed on these links are preserved, and new intermediate points are displayed at the moved node's initial position.

  The figures below show the results obtained with the Equal distance option when the Preserve path box is unchecked (figure 5.2) or checked (figure 5.3) for the connected links related to the nodes with two connections (represented by a red symbol).

• Check the Compute degree on selection check box if you want the connections of each selected node to depend on the number of its currently selected connected links. By default, this box is unchecked, causing the count to be determined by the number of connected links, whether these links are selected or not. When this box is checked, a node with three or more connections can be moved by the Linear Dispatch algorithm if it is selected and only two of its connected links are selected.

  The figures below show the results obtained with the Equal distance option when the Compute degree on selection check box is checked (figure 6.2) or unchecked (figure 6.3) for the schematic selected set defined in figure 5.1. The degree for Node 1 is 2 in all cases. For Node 2, even though its real degree is 3, this degree becomes 2 when the Compute degree on selection check box is checked. This is why Node 2 is moved by the Linear Dispatch algorithm when the Compute degree on selection check box is checked, and it is not moved when this check box is unchecked.

• Check the Move leaves check box if you want the nodes with three connections connecting at least one leaf node (pink/white circle symbol), the nodes with four or more connections for which two connected links connect nonleaf nodes, and all other links connecting leaf nodes (pink symbol) to also be moved during Linear Dispatch algorithm execution.
• Check the Expand leaves check box if you want the leaf nodes (that is, the nodes with one connection) to also be moved during Linear Dispatch algorithm execution. In this case, the Maximum shift parameter value specifies the maximum distance those nodes must be from the nodes to which they connect. When this distance is reached, leaf nodes are no longer moved. By default, the Maximum shift parameter value is 2 unless another value is specified for the diagram template related to the active diagram.

  The figures below show the results obtained with the Equal distance option when the Move leaves check box is checked and either Maximum shift = 2 (figure 8.2), or Maximum shift = 3 (figure 8.3).

  Figures 9.1 and 9.2 show the results obtained on the same diagram with the Equal distance option when both the Move leaves and Expand leaves check boxes are checked, using a maximum shift of 2 for the expanding distance.

Absolute units check box

By default, the minimum and maximum shift distance are interpreted as absolute units determined by the coordinate system specified on the XY Coordinate System tab of the Schematic Diagram Properties dialog box (Absolute units checked). Uncheck the Absolute units check box if you want these parameter values to be interpreted as relative units to the average of the current symbol sizes used to represent the schematic nodes in the diagram. In this case, when the Maximum shift parameter value related to the Expand leaves check box is 2, the distance that will separate leaf nodes from the nodes to which they connect will be, at most, the average size of two symbols placed side by side.

Note:

Specifying parameters in relative units is easier than in absolute units but has real meaning only when there is a reference scale for the diagram.

Restore Defaults button

Click the Restore Defaults button to reset all the Linear Dispatch parameters to their default values. The restored values are either those specified by default by Schematics or those specifically set as the default for the schematic diagram template related to the active diagram using the Schematic Dataset Editor Layout Task tab for this schematic diagram template.