# Laying out schematic diagrams

Schematic layout algorithms can apply to either the entire content or part of the active schematic diagram.

Three types of layout algorithms can be applied:

• Geoschematic
• Schematic
• Hierarchical

In addition, a particular schematic layout algorithm, Composite layout algorithm, can be specified to chain several schematic layout algorithms to one another.

Note:

The commands and tools related to schematic layout algorithm parameters and execution are all available from the Schematic Editor toolbar and are enabled after an editing session is started on the active schematic diagram.

## Applying schematic layout algorithms

Schematic layout algorithms apply to the active schematic diagram—that is, the schematic diagram selected from the Active Diagram list. An editing session must be started on this active diagram before any schematic layout algorithm can be executed on its content. If there is a selection on the active schematic diagram, the algorithm only operates on the selected schematic features. If no schematic features are selected in the active schematic diagram, the algorithm applies to the entire diagram.

Schematic layout algorithms generally execute according to predefined parameters. The parameter values can be edited on the Schematic Layout Algorithm dialog box.

Several schematic layouts can be executed on the same schematic diagram or on different parts of the schematic diagram.

The Composite layout algorithm allows you to specify a succession of schematic layout algorithms to be chained to one another as a single operation on the active schematic diagram.

The following steps detail how to apply a schematic layout algorithm to the active schematic diagram:

1. Click the desired diagram from the Active Diagram list.
2. Click Start Editing Diagram on the Schematic Editor drop-down menu.
3. Activate the data frame that contains the active diagram and click the Edit/Move Schematic Features button if you want to define a selected set of schematic features to which the schematic layout will be applied.
4. Click the desired layout algorithm from the Layout Task list.
5. For a hierarchical layout algorithm, use the Set Schematic Root and Set Schematic End tools if you want to specify root and end schematic nodes, respectively, so the hierarchical layout starts with the specified root schematic node and ends with the specified end schematic node.
Note:

The Set Schematic Root and Set Schematic End tools are only available for the hierarchical layouts that can take into account such specific root and end schematic nodes.

6. If the selected schematic layout works with parameters, click the Layout Algorithm Properties button to open the Schematic Layout Algorithm dialog box, and check or modify the desired parameter values.
7. Click OK to close the Schematic Layout Algorithm dialog box.

If you have specified new parameter values, these new parameters are taken into account by the selected schematic layout algorithm when it is applied to any schematic diagram of the same diagram template until you restore its default parameters or specify other parameters during the current ArcMap session.

8. Click the Apply Layout Task button to apply the selected schematic layout task to the active schematic diagram.

## Specifying schematic layout availability and layout default parameters

The availability of schematic layout algorithms and their default parameter values are managed and specified by the schematic diagram template. This management must be done using Schematic Dataset Editor and stored through the Layouts tab available for any schematic diagram template. This Layouts tab lists all schematic layout algorithms registered on the machine, each one represented by a specific item. Each algorithm item allows you to specify the following:

• Whether the schematic layout algorithm will be available from the Layout Task drop-down list in ArcMap
• The parameter values you want to be set by default on their associated properties tab
• Whether the Schematic Layout Algorithm Properties tab can be edited

These configurations apply to all diagrams of the schematic diagram template. When an algorithm's properties are editable for a particular diagram template, even if default parameter values are specified, you can specify other parameter values if needed. These parameters are used for the selected schematic layout algorithm until you restore its default parameters or specify other parameters during the current ArcMap session.

## Geoschematic layout algorithms

Geoschematic layout algorithms are used to separate schematic features that are visually close in your schematic diagrams while preserving the position of the schematic features as much as possible. The relative spatial positions of features are maintained, although the reference system is dropped. Detailed information can be displayed in the viewer or plot without zooming in and out. The desired effect of a geoschematic layout algorithm is to normalize the spacing of the node features while maintaining some of the original spatial relationship between the features.

Because they take the current position of the schematic features during their execution, geoschematic layout algorithms usually apply to schematic diagrams where schematic features are geographically positioned, but they can also apply to schematic diagrams that contain schematic features that are not geographically positioned.

Eight geoschematic layout algorithms can be applied to your schematic diagram:

### Geo - Angle Directed schematic layout algorithm

The Geo-Angle Directed layout algorithm progressively moves the diagram's schematic links in specified alignment directions. For each schematic link, the algorithm considers its current direction, searches for the nearest desired direction among those specified, and moves the link in that direction.

### Geo - Compression schematic layout algorithm

The Geo - Compression layout algorithm compresses the schematic features contained in a schematic diagram toward the middle of the diagram while trying to maintain relative positioning. It is useful for networks that span thousands of miles and are otherwise difficult to view and understand in their true geographic positions, for example, in the transmission utilities industry.

### Geo - Force Directed schematic layout algorithm

The Geo - Force Directed layout algorithm uses a physical analogy to draw graphs by considering a graph a force system in which it tries to locally minimize the energy. It searches for an equilibrium state of the force system—a position for each schematic node where the total force on each node is zero. Because this algorithm has a tendency to emphasize loops contained in a schematic diagram, it is often used by operators that manage highly meshed networks, such as water/wastewater or gas.

### Geo - Linear Dispatch schematic layout algorithm

The Geo - Linear Dispatch layout algorithm separates schematic nodes that are visually close to overlapping in the active schematic diagram. It moves these schematic nodes linearly along their connected schematic links. The movement depends on current node positions and on the parameters currently set on the Linear Dispatch tab. The Geo-Linear Dispatch layout algorithm works with the schematic links connected to the target nodes. It takes the number of connected links for these nodes into account, and the schematic link paths can be preserved.

This layout algorithm is especially useful for water/wastewater and gas, but it can be used in other industries as well.

### Geo - Spatial Dispatch schematic layout algorithm

The Geo - Spatial Dispatch layout algorithm separates schematic nodes that are visibly close to overlapping in the active schematic diagram based on their current positions and according to the parameters currently set on the Geo-Spatial Dispatch tab.

### Geo - Rotate Nodes Along Links schematic layout algorithm

The Geo - Rotate Nodes Along Links layout algorithm changes the rotation of symbols used to represent the schematic nodes according to the directions of their connected links. The nodes are rotated based on a given angle. The flow direction defined for the schematic links can be taken into account but isn't necessary. An option can be set so that the Geo - Rotate Nodes Along Links layout algorithm automatically executes each time schematic features are manually moved in the diagram or after another schematic layout algorithm is executed.

Note:

The rotation angle computed during algorithm execution is stored in the ROTATION field of each schematic feature class that implements the nodes in the schematic diagram. This ROTATION field must be turned on to symbolize the schematic nodes so they automatically rotate according to the computed angle values. In ArcMap, on the Layer Properties dialog box related to the desired node feature layer, you must click the Advanced button and click Rotation, then from the Rotate dialog box that opens, choose Rotation as the value for Rotate Points by Angle in this field. You also need to check the Arithmetic option so the assigned symbol is rotated as expected—that is, from the east in a counterclockwise direction.

Caution:

The Apply Layout Task button is enabled only when the ROTATION field is turned on for at least one of the feature layers inside the schematic diagram layer.

### Geo - Partial Overlapping Links schematic layout algorithm

The Geo - Partial Overlapping Links layout algorithm detects the collinear schematic links or the collinear portions of schematic links (the link segments) that overlap or nearly overlap in the active schematic diagram and separates them according to the parameters set on the Partial Overlapping Links tab.

The algorithm detects and groups together the parts of link segments that are close to each other, more or less parallel, and have more or less the same length. Segments in each set in the schematic diagram are spread equally on the left and right sides of the middle of the set of segments. The distance between each segment is then equal to the Offset parameter specified on the Partial Overlapping Links tab. The process preserves the original orientation of the segments so that a segment lying on the left side of another will still end up on the left side.

Note:

The Separate Overlapping Links schematic layout algorithm only operates on schematic links that connect the same origin and extremity nodes, but the Geo - Partial Overlapping Links algorithm operates on any schematic link and link portion.

### Geo - Initial Positions schematic layout algorithm

The Geo - Initial Positions layout algorithm restores the initial geometry for all the schematic features contained in the active schematic diagram. The schematic nodes are placed at the geographic positions, and the vertices initially placed along the schematic links are restored.

Note:

This schematic layout algorithm works without parameters.

## Schematic layout algorithms

When applying schematic layout algorithms to schematic diagrams, network connectivity is maintained, but the schematic nodes are positioned according to a set of rules that dictates their relative positions to create a patterned layout where the distances between nodes are normalized. This also includes managing and minimizing the amount of white space around adjacent nodes. The relative position of the nodes is not maintained, and the reference system is dropped. Spatial coordinate values are replaced by those generated from the layout algorithms.

Five schematic layout algorithms can be applied to your schematic diagram:

### Grid schematic layout algorithm

The Grid layout algorithm lays out the schematic nodes in the active schematic diagram relative to a magnetic grid. The nodes are moved based on their current positions and according to the parameters set on the Grid tab so that only one node holds a grid cell. The schematic nodes are placed along the grid from left to right and top to bottom in the order in which they are read from the database. This algorithm is used to construct a layout using grid points to move the schematic nodes.

### Main Ring schematic layout algorithm

The Main Ring layout algorithm arranges the schematic nodes and links in the active schematic diagram around the main ring and hierarchically lays out the schematic nodes and links that connect to the detected main ring nodes according to the parameters set on the Main Ring tab. The main ring is the loop formed by the largest number of links in the schematic diagram. If the schematic diagram contains no loops, the Main Ring layout algorithm execution has no effect. This algorithm is usually used by the telecommunications industry.

### Orthogonal schematic layout algorithm

The Orthogonal layout algorithm arranges the schematic nodes and links in the active schematic diagram orthogonally according to the parameters set on the Orthogonal tab. If a root schematic node is set for the active diagram, the Orthogonal algorithm computes the layout according to this root node. The root node is placed on the bottom, and the other schematic nodes and links are placed orthogonally starting from this node.

### Relative Main Line schematic layout algorithm

The Relative Main Line algorithm arranges the schematic nodes and links in the active schematic along parallel straight lines for which all the connected links have the same attribute value and places the branches coming from those lines, preserving both their directions regarding the straight lines and distances proportional to the initial distances and relative to each other. It operates according to the parameters currently set on the Relative Main Line tab. The algorithm can work from a root schematic node from which one of the straight lines—that is, the main line—starts. This root node can be specified using the Set Schematic Root tool . If no root node is specified, the algorithm automatically considers one of the schematic nodes the root node.

This algorithm can be applied to any kind of data but is particularly interesting to use on diagrams containing lines that are parallel, like those representing rail tracks.

### Separate Overlapping Links schematic layout algorithm

The Separate Overlapping Links layout algorithm operates on schematic links that connect to the same origin and extremity schematic nodes. It runs in two different ways:

• On schematic links that have the same origin and extremity nodes and the exact same path, as well as the same number of vertices, and all those vertices overlap so the links completely overlap
• On schematic links that have the same origin and extremity nodes but have different link paths

In both cases, the algorithm separates the detected links according to the parameters set on the Separate Overlapping Links tab. The Use origin links check box available on that tab allows you to switch from one way to the other.

### Reduce Vertices schematic layout algorithm

The Reduce Vertices layout algorithm removes vertices displayed along schematic links according to the angle that separates the segments incident to the vertices and the length of the segments that compose the links relative to the longest segment. If the conditions based on either the segment length or the angle formed by the incident segments are unverified, vertices are kept.

## Hierarchical layout algorithms

Hierarchical layout algorithms are schematic layouts that hierarchically arrange the schematic features contained in a schematic diagram. Four hierarchical layout algorithms can be applied to your schematic diagram:

### Hierarchical - Compact Tree schematic layout algorithm

The Hierarchical - Compact Tree layout algorithm arranges the schematic nodes and links in the active schematic diagram hierarchically and places them as a compact tree according to the parameters currently set on the Hierarchical - Compact Tree tab. It is used to optimize the placement of the schematic features along a corridor. The algorithm works from a root schematic node from which the resulting compact tree starts. This root node can be specified using the Set Schematic Root tool . If no root node is specified, the algorithm automatically considers one of the schematic nodes the root node.

### Hierarchical - Main Line Tree schematic layout algorithm

The Hierarchical - Main Line Tree layout algorithm arranges the schematic nodes and links in the active schematic diagram hierarchically along a main branch and places the schematic features according to the parameters set on the Hierarchical - Main Line Tree tab.

Using the Set Schematic Root and Set Schematic End tools, you can specify root and end schematic nodes in the diagram so that if there is a path between them, the algorithm works from a main line starting at the specified root node and ending at the specified end node. By default, when no root and end nodes are set, the detected main line is the branch with the largest number of links in the diagram.

In any case, the main line is centrally placed, with its related branches on either both sides or the left or right side, according to the Branch Placement option.

### Hierarchical - Radial Tree schematic layout algorithm

The Hierarchical - Radial Tree layout algorithm arranges the schematic features in the active schematic diagram hierarchically and places them in a radial tree according to the parameters set on the Hierarchical - Radial Tree tab. It detects the schematic node of the diagram that it uses as the circle center to arrange the subtrees starting from this root in concentric circles, each circle corresponding to one hierarchical level. If a schematic node is set as a specific root node, the radial tree considers this root schematic node the center of the concentric circles. The root schematic node can be specified using the Set Schematic Root tool .

This schematic layout algorithm provides a compact view of a hierarchical network. All industries can use this layout, but it is not recommended for use on a meshed network.

### Hierarchical - Smart Tree schematic layout algorithm

The Hierarchical - Smart Tree layout algorithm arranges the schematic features in the active schematic diagram hierarchically and places them in a smart tree according to the parameters set on the Hierarchical - Smart Tree tab. It works from a root schematic node from which the resulting smart tree originates. This root schematic node can be specified using the Set Schematic Root tool . If no root schematic node is specified, the algorithm automatically considers one of the schematic nodes the root node.

## Composite layout algorithm

The Composite layout algorithm allows you to configure a set of schematic layout algorithms that will be chained to one another in the order you specify when setting the Composite parameters.

Caution:

The Composite algorithm is not available by default in the Layout task in ArcMap. It must be enabled on the desired schematic diagram template's Layouts tab using Schematic Dataset Editor.

3/5/2014