Summary of coverage feature classes

A coverage is a collection of feature classes used to represent geographic phenomena. Each coverage is a directory stored as a series of files.

The set of features contained in a coverage depends on the type of geographic phenomena being modeled. The following table gives a brief description of the types of phenomena each feature class is used to model:

Coverage feature classes

Feature class

Application and use

Examples

Point

Point locations

Well sites, mountain peaks

Arc

Linear features

Street sections, contours, streams, sewers, power lines, gas lines

Node

Connecting points and endpoints of linear features

Valves on pipelines, intersections of streets, power poles, manhole covers

Route

Linear features

Streets, contours, stream networks, sewers, power line networks, gas line networks, street addresses

Section

Defines route features

Street section, traffic lanes, pipe condition, above- and below-ground transmission lines

Polygon

Area features

Soil units, land use, parcels, building footprints, forest stands, ownership

Region

Area features, multiple polygons

Census geography, state of Hawaii, overlapping wildlife habitat

Annotation

Feature labels

Street names, place-names on road maps

Tic

Geographic registration and control

Registration for digitizing

Link

Rubber sheeting and adjustment

Edgematching map sheets, feature snapping, datum adjustments

Coverage extent

Defines map extent

Rectangle describing outer boundary of coverage

Coverage feature classes
Coverage feature class file description

Feature class

Description

Attribute table name: <cover>.*

Point

A point defined by an x,y coordinate pair used to represent point features or assign User-IDs to polygons.

pat.adf

Arc

A line defined as a set of ordered x,y coordinates used to represent linear features and polygon boundaries.

aat.adf

Node

The endpoints of an arc or the point at which two or more arcs connect.

nat.adf

Route

A linear feature composed of one or more arcs or parts of arcs.

<route>.rat

Section

An arc or portion of an arc used to define a route or the building blocks of routes.

<route>.sec

Polygon

An area defined by the arcs that make up its boundary, including arcs defining any islands inside. User-IDs are assigned to label points.

pat.adf

Region

A collection of one or more contiguous or noncontiguous polygons defining a geographic feature.

<region>.pat

Annotation

A text string describing a geographic feature. Shape points are used to position and draw annotation.

<anno>.tat

Tic

A geographic reference or control point used to register and transform the coordinates in a coverage.

tic.adf

Coverage feature class file description

Related Topics

3/3/2014