1. Physical Structure of GDB
Geodatabase
Feature datasets
Spatial Reference
Object classes, subtypes
Features classes, subtypes
Raster datasets
Rasters
Relationship classes
Geometric networks
TIN datasets
nodes, edges, faces
Planar topologies
Locators
Domains
Addresses, X.Y location
ZIP Codes, Place names
Validation rules
GIS Project

2. Modeling with Networks
Geography, KHU,
Jinmu Choi
Overview on Network Model (3)
Network Models (4)
Connectivity in Networks (3)
Types of Feature Classes in Network (4)
Elements for Network Analysis (7)
Building Networks (6)
Summary and Next…
GIS Project

3. What is a Network?
Networks describe a connected graph of GIS objects that can be traversed
Important for modeling pathways and navigation
Transportation, pipelines, utilities, hydrology, and many other network-based applications
Street features represent edges that connect at their endpoints (called junctions)
Turns model the movement
for traveling from one edge
to another
GIS Project

4. Why Network? Editing networks is easy
Network features can represent complex parts of a network, such as switches
A suite of simple and advanced network analysis solvers is built into ArcGIS, ready to use
Networks can be versioned
GIS Project

5. Solving Problems To define and analyze the flow of resources to answer
Which streams will be affected by a proposed dam? (allocation problems)
Which areas will be affected by a water main repair? (allocation problems)
What is the quickest route between two points in the network? (routing problems)
Tracing, spatial Interaction using gravity model
GIS Project

6. Network Models Network types:
Geometric network: edge and junction features with coordinate values
Logical network: edge and junction tables without coordinate values
A geometric network is the representation of geographic features that comprise a network
A logical network is a pure graph of junction and edge elements
GIS Project

7. Geometric Network Model
Lateral
Service
Main
Feed
Valve
Geometric Network
A collection of features comprise a connected system of edges and junctions
Nonplanarity: A bridge over
a road
Network feature classes
Simple or complex junction feature
Simple or complex edge feature
Characteristics
To establish relationships
Behaviors: preserve connectivity and update network elements
GIS Project

8. Logical Network Model A collection of edges and junctions
To store the connectivity information
Not a feature, just element
Network features are associated with logical network elements
Logical network elements are automatically updated when the network features are edited
GIS Project

9. Example: Network models
Geometric Network
Logical Network
Junction element table
Feature Class
Feature id
Element ID
Cities
Major rails 1 j1 id
geometry id
geometry j1 r1 1 j2 1 j2 r2 1 j3 2 j3 1 j4 3
Truck routes j4 id
geometry
Edge element table t1
Feature Class
Feature id
Element ID 2 r1 10 2 r2 11 r2 j1 j2 j3 j4 r1 t1 3 t1 12
Connectivity table
Junction
Adjacent junction and edge
2, 10 1
2, 12 2
0, 10
1, 12
3, 11 3
2, 11
GIS Project

10. Geometry and Connectivity
Geometric network contains features and geometry
Logical network
contains elements
and connectivity
Connectivity is
established
via geometric
coincidence
GIS Project

11. Connectivity Rules
Network connectivity rules constrain the type of network features
Not all edges can connect to all junctions
: edge – junction rule
Not all edges can connect to other edges through a specified junction: edge – edge rule
To maintain the integrity of the network features in a geometric network
Using validation, you can check the errors based on the connectivity rules
GIS Project

12. Basic Rule Type Edge-junction rule Edge-junction cardinality
Meter cannot be connected
to High voltage
Switch only accept
between two and four lines
Service tap
Yes
meter
switch
Yes No
transmission main
meter
switch No
Edge-edge rule
Default junction type
Only reducer can connect edges
Transformer can be
automatically inserted
Yes
28 kV
14 kV No
transformer
GIS Project

13. Simple Feature Classes
A simple edge feature is associated with a single line in a logical network: line or curve
A simple junction feature is a feature associated with a single node in a logical network: Point
1:1
1:1
Simple edge
Simple junction
GIS Project

14. Complex Feature Classes
A complex edge feature is associated with any number of edges in a logical network: Chain
A complex junction feature is associated with a collection of junctions and edges in a logical network: a set of points and lines
1:M
PMH- 7
1:M
Complex edge
Complex junction
GIS Project

15. Complex Edge Features
Ideal single main can be broken into multiple edges to model flow
GIS Project

16. Complex Junction Features
For modeling networks within networks
A switch cabinet in an electrical network
GIS Project

17. Network Flow Two operational context of network
Utility network: no will
Transportation network: its own will
Elements to determine network flow or travel
Sources and sinks
Disabled features
Weights
Indeterminate flow
Uninitialized flow
GIS Project

18. Sources and Sinks
In a utility network, sources and sinks are used to determine flow direction
Sources: a flow starts
Sinks: a flow terminate
If they are set to use, an individual junctions can be specified either a source or sink
GIS Project

19. Disabled Features and Weights
All features in a network have an enabled /disabled status
Disabled: nothing flows into or out of it
Weights are the attributes of edges and junctions
Storing travel costs
Stored in a logical network
GIS Project

20. Indeterminate or Uninitialized Flow
Indeterminate flow
Sources, sinks, disabled features do not give enough information
Flow direction cannot be established
Uninitialized flow
Isolated flow because the edges are disconnected from the rest of networks
GIS Project

21. Elements in Analysis Solvers: network analysis program
Tracing solver, shortest path solver…
Tracing: a solver to follow a flow in a network until some condition is met
Need Flags and Barriers
Upstream trace, downstream trace, isolation trace, and path trace
Weights for transportation analysis
Shortest path solver uses various weights to calculate traveling cost
GIS Project

22. Flow Analysis on a Network
Flags: a location on a network to represent a multitude of real-world objects
Start point of tracing, locations of valves, locations of services… (EdgeFlags and JunctionFlags)
Barriers: temporarily disabled elements in a network
Start an edit session in Editor toobar
Use Utility Network Analyst
Generate Flow using Flow button
GIS Project

23. Transportation Analysis
Start an edit session in Editor toolbar
Use Network Analyst
Show/Hide
Analysis
Window
Create
Network
Location
Move
Solve
Direction Window
GIS Project

24. Creating Geometric Network
State ArcCatalog
Right Click
Feature
Dataset
Select
New/
Geometric
Newtork…
GIS Project

25. Geometric Network Wizard
Step by step wizard…
Build a geometric network from existing features
GIS Project

26. Network Wizard (cont.) Select feature classes for a geometric network
Enabled values
GIS Project

27. Network Wizard (cont.)
Complex or Simple edges
Snapping
GIS Project

28. Network Wizard (cont.)
Sources and Sinks
Weights
GIS Project

29. Network Wizard (cont.)
Summary & Creating…
Network in GDB
GIS Project

30. Summary Overview on Network Model Network Models
Geometric or Logical Network Models
Connectivity in Netowrks
Edge-junction and edge-edge rules
Types of Feature Classes in Network
Simple or complex edges and junctions
Elements for Network Analysis
Flow using sources and sinks
Solvers, NetFlags, Barriers, Tracing, Weights…
Building Networks
GIS Project

31. Next… Lab: Simple analysis with networks Finding Locations Read
Modeling Our World
Ch 11
GIS Project