Implementing
Geometric Networks in
PODS ESRI Spatial 5.0
J. Tracy Thorleifson
Eagle Information Mapping, Inc.
Contents
1
Linear Referencing in
Geometric Networks & Arc Schematics
2
Overlapping edges in
Geometric Networks
3
Options for Network implementation in
PODS ESRI Spatial
4
Example implementations
Linear Referencing in Geometric Networks
 Do edge features in a Geometric Network
support measures?
 Yes!
 Edge features support both measure and Z values
 Can edge features in a Geometric Network be
used as route features for route event layers?
 Yes!
 Any Polyline M edge feature class in a Geometric
Network can be used to support route event layers
Linear Referencing in Arc Schematics
 Do links in an Arc Schematics feature class support
linear referencing?
 Yes and no…
• M values from the data source feature class are not preserved
• Link features in a Schematics feature class store M values, but these
values are set by Arc Schematics
• Identify M’s tool does not work with a Schematics feature class
 Can Arc Schematics link features be used as route
features for route event layers?
 No, but…
• Arc Schematics supports “Node on Link” and “Sub Link” feature
types
• Custom XML Builder and/or geoprocessing code is currently
required
Topology in a Geometric Network
 Network topology is determined solely by spatial coincidence of
junctions and edge-ends
 Overlapping edges do not result in connectivity or geometry errors as
long as junction / edge-end topology is maintained
 Editing considerations
 Any editing tool that maintains junction / edge-end topology is necessary
and sufficient
• Generic ArcMap Edit tools – make sure to properly manage the ‘snapping’
environment
 Junction edits in a geometric network also move connected edges;
edges are ‘anchored’ at the next junction
• Can be problematic in PODS ESRI Spatial where all online features may not
participate in the network – non-network online features will not move
• Centerline edits should be ‘anchored’ by control points – the net junction
adjacent to the one being edited may not be a control point, causing the
introduction of a centerline deflection without a corresponding control point
Overlapping Edges in Geometric Networks
 Overlapping edges of different types for a single entity
(e.g. a single pipeline) are not a problem
 There is only a single path through the overlapping edges
• Find connected, find path and trace all work
• Find loops is useless, since all overlapping edges are ‘looped’ by
defintion
 Overlapping edges for two or more entities (i.e. multiple
pipelines) are a problem
 The network analysis tools can’t tell that the overlapping edges
belong to different entities
• Find connected, find path, find loops and trace return spurious
results
Considerations for implementation
 Primary intended use
 Support for hydraulic modeling?
 Outage modeling?
 Creation of schematic diagrams?
 Geometric networks require feature classes as
input
 Route event-based layers cannot be used in a
geometric network
 In implementations with overlapping edges, use
the complex edge type for edge features
Geometric Network Option 1 – “Classic”
 Only include features in the network through
which product actually flows
 Pipe segments, valves, tees, meters, taps, etc.
 Model sources and sinks
 Model connectivity rules
 Best for:
 Supporting export to hydraulic modeling applications
 Application of network analysis tools in ArcMap
• Outage modeling, flow tracing, etc.
Geometric Network Option 2 – “Schematic”
 Include all features in the network that you might
want to see in a schematic diagram
 StationSeries + whatever!
 Don’t worry about sources and sinks, or connectivity
rules
 Best for:
 Arc Schematics diagram creation
• The standard builder is optimized for geometric networks and
deals nicely with all feature classes participating in the
network
Geometric Network Option 3 – “Event-Based”
 Include only StationSeries in the network
 Use schematic diagram rules to add non-network
features to a schematic
• Spatial query rule
• Relationship rule
 Use a custom XML builder to include route events in a
schematic
 Best for:
 Really only useful for schematics generation, as nonnetwork features appear only in the schematic
diagram
Sample Steam Injection Network
Steam Injection Legend
Option 1 – Schematic for “Classic” Network
 All productcarrying features
participate in the
network
 PipeSegment is
the only edge
class
 StationSeries is
not included
Option 2 – Schematic for “Schematic” Network
 All productcarrying features
participate in the
network
 PipeSegment
and
StationSeries are
both present as
complex edge
features
Option 3 – Schematic for “Event-Based” Network
 StationSeries is
the only feature
class in the
network
 Cogen, Well,
Well Tester,
Steam Manifold
and Closure are
all “offline”
features
 Placed in the
diagram with a
spatial query rule
Conclusion
 Geometric networks are wholly compatible with linear
referencing as implemented in PODS ESRI Spatial
 Overlapping edges resulting from StationSeries features and
online polyline event features are generally a non-issue
 A variety of options are possible when implementing a
geometric network with PODS ESRI Spatial
 The option selected is dependent on intended use of the network
 Arc Schematics paired with a geometric network-enabled
PODS ESRI Spatial Geodatabase is a useful display and
visualization tool