Creating a geometric network
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Feature classes stored in the same feature dataset can participate in a geometric network. Geometric networks model network systems such as water networks. You will see how to build a geometric network from the feature classes in the Water feature dataset in the Montgomery geodatabase. You will then see how to create connectivity rules to define which features can connect to each other in the network.
The Build Geometric Network Wizard will be opened. You can use this wizard to either build a geometric network from existing feature classes or to create an empty geometric network.
The second panel is used to specify whether to build a network from existing feature classes or to create an empty one. You want the default—Build a geometric network from existing features.
The next step is to select which feature classes in the feature dataset will participate in the geometric network and what the name of the network will be.
The next setp is to choose whether to enable all features or exclude features with particular values in the 'Enabled' field. The option to exclude features with certain attributes makes it easier to manage the state of parts of the network if you need to drop the network and rebuild it after you’ve been working with it for a while. In this example you click No, so that all features will participate in the geometric network.
The next step is to specify which line feature classes will become complex edge feature classes in the geometric network. Complex edge features are not split into two features by the connection of another feature along their length; thus, they are useful for modeling water mains which may have multiple laterals connected to them. By default, all line feature classes become simple edge feature classes.
In this example, two of the line feature classes, Distribmains and Transmains, will become complex edges.
The next step is to choose whether to use snapping when the network is assembled. Features in a geometric network must be precisely connected to one another. The input feature classes can be adjusted to ensure connectivity by snapping. You can specify whether these features need to be adjusted to snap to one another in the network-building process.
In this example some of the features need to be adjusted. When you have snapping, you need to set a snapping tolerance. In this example, the snapping tolerance is 1.0. This means that parts of features within one of the coordinate system units of another feature will be snapped together. In this example all of the features stored in each feature class can be adjusted.
The next step is to specify which, if any, of the junction feature classes can act as sources and sinks in the network. Sources and sinks are used to determine the flow direction in the network. In this example the features in the Tanks feature class can be sources or sinks in the network.
The next step is to choose whether ot not to assign network weights. A network weight describes the cost of traversing an element in the logical network, such as the drop in pressure as water flows through a pipe. This geometric network does not require weights, which is the default.
The final panel of the wizard summarizes the choices for this geometric network.