Essential trace network terms are listed along with their descriptions.
Analytics is the process of analyzing the trace network data to perform inspections of the network (trace network traces) and schematically represent the whole or parts of the trace network (network diagrams).
A complex edge allows resources to enter one end of the edge and exit the other end of the edge just like a simple edge; however, it also allows resources to flow in or out along the edge feature without the need to physically split the edge. For example, a Class 5 trail in a trail network that represents a fully developed pathway may exist as a single complex edge in a network with multiple trails connected along its length through midspan junctions representing trailhead locations. These junctions are connected and would not split the edge.
This behavior is supported with complex edges because they allow midspan connectivity.
Network features in a trace network can be connected to each other with a shared endpoint, vertex, or point (common x-, y-, and z-values). This is called connectivity.
A pump placed at the end of a water pipe will have connectivity established because of the shared location.
The diagram view shows a schematic view of your network. A diagram is a symbolic representation of features in a trace network with an applied visualization technique. Diagrams can also show the results of a tracing analysis.
Dirty areas mark modified features in a map that are out of date in the network topology. They are used as visual cues to show the areas that must be validated to maintain the network topology. Dirty areas are cleared when the network topology is validated.
A new line representing a canal is constructed on the map, and a new dirty area is created that is visible around this feature.
The trace network is comprised of a logical network of junction and edge elements. Edge elements comprise the logical component of edge (or line) features in a trace network. A complex edge feature is associated with a set of junction and edge elements in the logical network.
A stream segment represented by a single line feature may be composed of multiple edge elements
When two or more features exist in the same x-, y-, and z-location, they are geometrically coincident.
Sometimes features occupy the same x- and y-locations. Assigning z-values to features at the same x- and y-locations will help ensure features are not geometrically coincident.
The map view shows a cartographic display of your trace network. When edits are performed, dirty areas appear on the map showing where the network topology is not current.
When connecting network features to a line that acts as a complex edge feature, you can make connections at either the endpoints or the midspan vertices of a line. This establishes midspan connectivity on the edge feature. As with simple edges, complex edges are always connected to at least two junctions at their endpoints, but they also support connectivity to additional junctions along their length. If a new junction is snapped midspan on a complex edge, the complex edge remains a single feature. Snapping the junction causes the complex edge to be split logically; for example, if the feature corresponded to a single edge element in the logical network before the junction was connected, it is now represented by two edge elements.
Network attributes are associated with attributes on features in your network. They are derived from feature attributes and cached inside the network topology to aid in performance while feature attributes are evaluated during a trace. The values stored as attributes for features on a map are reflected or updated in the associated network attribute each time you validate the network topology.
Surface type for paths can be defined as a network attribute to constrain traversability over unpaved paths.
Network diagrams provide a simplified view of a network, which is useful for various types of engineering analysis. These are also called schematic representations and apply user-specified algorithms to collapse nonessential features and highlight essential features for an engineer's view of the network.
The network topology enables tracing analysis and rapid retrieval of network features. When edits occur on a trace network, affected parts of the network topology are displayed as dirty areas to indicate that the network topology does not match the edited features. A validate network topology operation will update the associations in the area where edits took place and produce accurate tracing results.
To learn more, see Network topology.
A preset template allows you to quickly place a complex collection of features. Preset templates create all types of associations as well as place network features. Preset templates are part of the core ArcGIS Pro editing framework.
A simple edge allows resources to enter one end of the edge and exit the other end of the edge. The resource cannot be siphoned off or exit along the simple edge; it can only leave the edge at its endpoint. An example of a simple edge is a first-order stream in a hydrological network. First-order streams can feed other streams but can have no tributaries themselves. Simple edges are always connected to two junctions, one at each end, and do not support midspan connectivity.
A system junction is a read-only, system-provided network feature that is placed at the endpoint of a network edge element when there is no user-defined junction. System junctions are generated during the initial enabling of the network topology or through validation of the network topology.
There are a few situations in which system junctions are created:
- A single edge element with no user-defined junctions at the endpoints
- Two edge elements that share an endpoint and do not have a user-defined junction connecting them
Common types of analysis done with a network involve traces. With a trace analysis, you can identify every network feature that is connected to a source or find all features upstream or downstream from a selected point.
Examples of trace analysis are shortest path traces, upstream traces, downstream traces, and connected traces.
The trace network uses a set of connected edges, junctions, or both in conjunction with network attributes, also known as network weights, to model the flow of resources through the network. Feature classes in a feature dataset provide the source junctions and edges used to create a trace network. Connectivity in the trace network is based on the geometric coincidence (x,y,z) of the features used as data sources and is established when the network topology is enabled.
Two related concepts in the trace network are connectivity and traversability. Connectivity describes the potential range of the resource flow (water, gas, or other). Traversability describes the actual range of resource flow according to the current state of feature or filter barriers that can impede flow.
A water system can have many connected pipes, but closed valves disconnect zones of water delivery from one another and act as a barrier. Alternatively, a network attribute can be used to constrain traversability in the network, limiting the flow of a resource.