Jensen Chapter 7

geocoding

A GIS operation for converting street addresses into spatial data that can be displayed as features on a map, usually by referencing address information from a street segment data layer.

TIGER/Line files

A digital database of geographic features, covering the entire United States and its territories, that provides a topological description of the geographic structure of these areas. TIGER/Line files define the locations and spatial relationships of streets, rivers, railroads, and other features to each other and to the numerous geographic entities for which the Census Bureau tabulates data from its censuses and sample surveys.

impedance

A measure of the amount of resistance, or cost, required to traverse a path in a network, or to move from one element in the network to another. Resistance may be a measure of travel distance, time, speed of travel multiplied by distance, and so on. Higher impedance values indicate more resistance to movement, and a value of zero indicates no resistance. An optimum path in a network is the path of lowest impedance, also called the least-cost path.

directed network

A network in which edges have an associated direction of flow. In a directed network, the resource that traverses a network's components cannot choose a direction to take, as in hydrologic and utility systems.

undirected network

A network where each edge may or may not have an associated direction of flow. In an undirected network, the resource that traverses a network's components can decide which direction to take, such as traffic in transportation systems.

route

A path through a network

address matching

A process that compares an address or a table of addresses to the address attributes of a reference dataset to determine whether a particular address falls within an address range associated with a feature in the reference dataset. If an address falls within a feature's address range, it is considered a match and a location can be returned.

target market share

A type of location-allocation modeling that chooses the minimum number of facilities necessary to capture a specific percentage of the total market share in the presence of competitors. You set the percentage of the market share you want to reach and let the solver choose the fewest number of facilities necessary to meet that threshold.

maximize market share

A type of location-allocation modeling where a specific number of facilities are chosen such that the allocated demand is maximized in the presence of competitors. The goal is to capture as much of the total market share as possible with a given number of facilities, which you specify. Large discount stores typically use Maximize Market Share to locate a finite set of new stores.

maximize attendance

A type of location-allocation modeling where facilities are chosen such that as much demand weight as possible is allocated to facilities while assuming the demand weight decreases in relation to the distance between the facility and the demand point

maximize coverage

A type of location-allocation modeling where facilities are located such that as many demand points as possible are allocated to solution facilities within the impedance cutoff. Maximize coverage is frequently used to locate emergency services such as fire stations, police stations, and ERS centers as emergency services are often required to arrive at all demand points within a specified response time.

minimize impedance

A type of location-allocation modeling where facilities are located such that the sum of all weighted costs between demand points and solution facilities is minimized. This problem type is traditionally used to locate warehouses It can reduce the overall transportation costs of delivering goods to outlets. It also is used to locate public-sector facilities such as libraries, regional airports, museums, department of motor vehicles offices, and health clinics.

network service area analysis

A type of network analysis for determining the region that encompasses all accessible streets (streets that lie within a specified impedance). For example, the 20-minute service area for a network location (such as a fire station) includes all the streets that can be reached within 20 minutes from that location.

closest-facility analysis

A type of network analysis for finding the closest locations (facilities) from sites (incidents), based on the impedance chosen. For example, finding hospitals near a car accident. When finding closest facilities, users can specify how many to find and whether the direction of travel is toward or away from the site (incident). Users can also specify a cutoff threshold beyond which the analysis will not search for a facility. For example, finding hospitals within 6 miles of a car accident.

network

An interconnected set of points and lines that represent possible routes from one location to another. For geometric networks, this consists of edge features, junction features, and the connectivity between them. For network datasets, this consists of edge, junction, and turn elements and the connectivity between them. For example, an interconnected set of lines representing a city streets layer is a network.

traveling salesperson route analysis

An optimum route analysis in which a salesperson, for example, must find the most efficient way to visit a series of stops, then return to the starting location. This type of route analysis is common for delivery services like UPS.

junction

For network data models in a geodatabase, a point at which two or more edges meet.

origin-destination cost matrix

In ArcGIS Network Analyst, a type of network analysis that computes a table containing the total impedance from each origin to each destination. Additionally, it ranks the destinations that each origin connects to in ascending order of the time it takes to travel from that origin to each destination.

center

In network allocation, a location from which resources are distributed or to which they are brought.

MAF

Master Address File. Developed by the Census Bureau to geocode addresses for census tabulations. After 2000, it was merged with the TIGER databases to form MAF/TIGER.

kernel

On a raster, an analysis boundary or processing window within which cell values affect calculations and outside which they do not. Filters are used mainly in cell-based analysis where the value of a center cell is changed to the mean, the sum, or some other function of all cell values inside the filter. A filter moves systematically across a raster until each cell has been processed. Filters can be of various shapes and sizes, but are most commonly three-cell by three-cell squares.

address range

Street numbers running from lowest to highest along a street or street segment. Address ranges are generally stored as fields in the attribute table of a street data layer. They often indicate ranges on the left and right sides of streets.

shortest path

The best route or the route of least impedance between two or more points, taking into account connectivity and travel restrictions such as one-way streets and rush-hour traffic.

location-allocation

The process of finding the best locations for one or more facilities that will service a given set of points and then assigning those points to the facilities, taking into account factors such as the number of facilities available, their cost, and the maximum impedance from a facility to a point.

edge

n a network system, a line feature through which a substance, resource, or traffic flows. Examples include a street in a transportation network and a pipeline in a sewer system.