Topic 11 Flashcards
(20 cards)
network GIS
system of linear features that has the appropriate attributes for the flow of objects
networks and connectivity
all networks are based on assessing connecvitivty among network elements
network analysis and graph theory
the way we conceptualize networks has may origins in mathematics
graphs are visual representation of the elements and connections in a system
two types of networks in Arcgis
utility (geometric)
topoligical networks (network datasets)
utility (geometric) networks
used to model things like power utility networks, pipeline netowkrs, stream networks
topological networks
used to model things like road networks, rail networks, trail system in a park
agents have a choice in the direction of travel
requires explicit topological relationships to be established
utility networks (detailed)
simple networks of nodes and edges that represent network shaped geographic features
uses, calculate shortest path between two points
find all connected or disconnected network elements
transportation networks (network datasets)
needed to model the movements of commodities or agents that have free will
defined as a series of edges junctions, and turns
can be modelled as multi modal networks
ex. walk on campus
junction points
represent road intersections
edges
represent segments of the road network that connect two road intersections
flow of the network
turn features
constrain flow in certain directions
ex. one way streets
impedance matrix
to understand patterns of flow in the network, the GIS uses the network graph to construct an impedance matrix
routing
find the quickets, shortest, or most scenic route form one location to another
relies on the concept of impedance or cost along edges
travelling salesperson problem
set of points (ex. customers) must be visited
so what is the most efficient order
vehicle routing problem solver
extends the travelling salesperson problem to include logistical considerations
issues with routing
another class of geographic problems involve the location of optimization of routes through a network
types of network analysis: closest facility
find the closest police car to a crime area, taxis to a fare etc
can specify closest facility or rank order of number of options
often used with routing
origin destination (OD) cost matrix
define a cost matrix for travel among multiple locations
used to optimize routes among multiple origins and destinations
service areas/accessibility
find service areas around any location on a network
defined by a network area within a given parameter
location-allocation analysis
chose from a set of facilities or locations based on their potential interaction with demand points
