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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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