-
Interapplication
communication. The capability of one computer program to communicate with
another program. With IAC, two (or more) programs can execute
simultaneously, share data, and make requests of each other. ArcInfo
Version 7 and ArcView Version 2 support IAC. IAC tools in AML (ARC Macro
Language) support real-time GIS, a network GIS process server,
interoperability, and open integration between ArcInfo and other
applications. In a client/server environment the command references on the
client side are IACCONNECT, IACDISCONNECT, and IACREQUEST; on the server
side are IACOPEN, IACCLOSE, and &IACRETURN.
-
The
topological overlay of a coverage (input) with a polygon coverage
(identity). For each feature in the input coverage, the intersection with
identity features is determined, creating new features of the same feature
class as the input coverage. For example, a road (input coverage, arc
feature class) passing through two counties (identity coverage) would be
split into two arc features, each with the attributes of the road and the
county it passes through. Compare with
intersect and
union.
- identity link
-
A coverage link whose
from-location is the same as its to-location. Used to control rubber
sheeting and adjustment operations. Identity links act as nails to hold
down the point location during adjustment. See also link.
- IEEE
-
Institute of Electrical and
Electronics Engineers. IEEE Standard 1003.1-1990 (aka POSIX.1) defines C
program interfaces for the operating system that enable source code
portability beyond the ANSI C definition (see
POSIX). ArcInfo and ArcView are fully compatible with network
protocols that support IEEE 802.5, FDDI and X.25 transport standards.
- IGDS
-
Interactive Graphics Design
Software. Intergraph IGDS file formats can be converted to and from
ArcInfo coverages.
- IGES
-
Initial Graphics Exchange
Specification (IGES) is a common data format used for transfer of CAD
data. IGES files can be converted to and from ArcInfo coverages.
- image
-
A graphic representation or
description of a scene, typically produced by an optical or electronic
device. Common examples include remotely sensed data (e.g., satellite
data), scanned data, and photographs. An image is stored as a raster data
set of binary or integer values that represent the intensity of reflected
light, heat, or other range of values on the electromagnetic spectrum.
- image catalog
-
An organized set of
spatially referenced, possibly overlapping, images that can be accessed as
one logical image. An image catalog is a group of images on disk, each
referenced by a record in an INFO data file. At a minimum, items in the
data file include the image pathname and the bounding coordinates xmin,ymin
and xmax,ymax.
- image integrator
-
A collection of image
management and display tools in ArcInfo that allows vector and raster data
to be displayed concurrently. Image integrator commands georeference
images to real-world coordinates, display images, and manage image
catalogs.
- image processing
-
Computerized routines for
information extraction (e.g., pattern recognition, classification) from
remotely sensed images to obtain categories of information about specific
features.
-
The amount of resistance
(or cost) required to traverse a line from its origin node to its
destination node or to make a turn (i.e., move from one arc through a node
onto another arc). Resistance may be a measure of travel distance, time,
speed of travel times the length, and so on. Higher impedance indicates
more resistance to movement, with 0 indicating no cost. Often, a negative
impedance value indicates a barrier. Impedance is used in network routing
and allocation. An optimum path in a network is the path of least
resistance (or lowest impedance).
- import
-
Process of bringing data or
software from one system into another.
- in-situ
-
The measurement and
recoding of information, data, or some property of an object or phenomenon
by a device that is in physical contact with the object or phenomenon
being studied.
- index
-
Special data structure used
in a database to speed searching for records in tables or spatial features
in geographic data sets.
ArcInfo supports both
spatial and attribute indexes. See also item indexing,
cross-tile indexing and
spatial indexing.
- index coverage
-
The polygon coverage that
describes, and is used as a spatial index for, the tile structure of a
layer. Each polygon in an index coverage corresponds to a tile.
- INFO
-
A tabular DBMS used by
ArcInfo to store and manipulate
feature attribute tables and other related tables.
- INFO database
-
The contents of a set of
INFO data files, feature attribute tables, and related files stored in
each ArcInfo workspace under a subdirectory named INFO. This subdirectory
contains all feature attribute tables for the set of coverages contained
in the workspace.
- information system
-
A system that contains or
is related to a database of information and also provides the means of
data storage, retrieval, and analysis, so that a user may query and
receive answers from the database.
- INFORMIX
-
A relational database
management system to which ArcInfo has access through the DATABASE
INTEGRATOR.
- INGRES
-
A relational database
management system to which ArcInfo has access through the DATABASE
INTEGRATOR.
- infrastructure
-
Human-made systems that
provide any or all of the normal public services to an urban area (e.g.,
water supply, sewage, utilities, traffic control).
- Initial Graphics Exchange
-
Specification (IGES) An
interim standard format for exchanging graphics data between computer
systems.
- input
-
(Noun) the data entered
into a computer system. (Verb) the process of entering data.
- integer
-
A number without a decimal
(0, 1, 25, 173, 1032, etc.). Integer values can be less than, equal to, or
greater than zero.
-
Interaction is a measure of
the estimated number of trips that will be generated between origins and
destinations for a particular activity. Interactions depend upon the
properties of the origin to generate a trip, the property of the
destination to attract a trip and the cost of traveling between them.
- interaction matrix
-
A generated INFO file
containing the number of interactions occurring between a set of origins
and destinations. The interaction matrix can be analyzed to make
trade-area maps.
- inter-application communication (IAC)
-
A technology that enables
software applications on remote or local machines to communicate with each
other. IAC makes it possible to develop applications that seamlessly
integrate the capabilities of a number of programs by providing a way for
external applications to request services of ArcInfo and for an
AML
application to exploit the capabilities of other applications.
- interface
-
For data communication, a
hardware and software link that connects two computer systems, or a
computer and its peripherals.
- internal number
-
See
Cover#.
- Internet
-
An international consortium
of wide area networks that operate using a standard set of addresses
allowing machine-to-machine connectivity on a global scale. The Internet
is an outgrowth of a Defense Advanced Research Projects Agency (DARPA)
research project in the early 1970s to provide connectivity between
scientists running computer simulations in different locations. Additional
regional, private, and public networks have joined the Internet over time.
At this point there are over two million computers that now have direct
access to the resources on the Internet. ESRI operates a discussion group
on the Internet called ESRI-L. ESRI-L is open to the general public and is
available to any Internet subscriber. It was established to give ArcInfo
users a way to exchange technical questions and information.
- interpolation
-
The estimation of z values
of a
surface at an unsampled point based on the known z values of
surrounding points.
-
The topological integration
of two spatial data sets that preserves features that fall within the area
common to both input data sets. See also identity
and
union.
- intervisability
-
Planning tool used for
siting features in a landscape through application of digital functions
elevation data. It shows what can be “seen” from specified target
locations. It can map the area visible from a scenic lookout or the area
that can be detected by a radar antenna. It can show how a road or cleared
land can be effectively hidden from view. Sometimes referred to a viewshed
modeling or viewshed mapping.
- ISDN
-
Integrated Services Digital
Network, provides WAN (see
WAN)
combined transmission of analog and digital services. ISDN is offered as a
Basic Rate Service on either one or two channels for WAN services of
either 64 kbps or 128 Kbps. ISDN services are available from a
long-distance telephone company.
- island polygon
-
A polygon lying completely
within another and not sharing a common boundary (e.g., an island in a
lake).
-
The International
Organization for Standardization. A worldwide federation of national
standards bodies (e.g.,
ANSI
from the U.S.) that develops international standards. A Technical
Committee (ISO/TC211) is developing international Geographic Information/Geomatics
standards. Among many other computing standards, ISO maintains an SQL
standard and is developing an extended version, SQL3, which will support
queries on geographic data sets.
- ISO 8211
-
The third of three parts of
the SDTS (see
SDTS)
that specifies data transfer implementation (i.e., encoding method). ISO
8211 is a general-purpose, media-independent interchange standard whose
variable length records may be written on any medium that is able to
accept them, including communications lines.
- ISO 9000
-
Established in 1987, ISO
9000 is an international set of five related standards for qualification
of global quality assurance and quality control standards. Adherence is
accomplished through an application process for ISO 9000 certification in
company standards for inspecting production processes, updating records,
maintaining equipment, training employees and handling customer relations.
The governing international consortium is recognized worldwide.
- ISO 9660
-
Volume and file structure
of CD-ROM for Information Interchange. A standard for the organization of
data on CD-ROM media established by the International Standards
Organization.
- isoline
-
A line on a surface
connecting points of equal value.
- isopleth map
-
A map displaying the
distribution of an attribute in terms of lines connecting points of equal
value; See contour, contrast with Chropleth map.
-
A column of information in
an attribute table, for example, a single attribute of a record in an INFO
data file.
-
A means of accelerating
logical queries and tabular 'relates' by creating an index on an item in a
database table.
- ITUM
-
Integrated Terrain Unit
Mapping is an example of integrated data management. It is the process of
adjusting terrain unit boundaries so that there is increased coincidence
between the boundaries and occurrences of interdependent terrain variables
such as hydrography, geology, physiography, soils and vegetation units.
- jaggies
-
Jargon term for curved
lines that have a stepped or saw-tooth appearance on a display device.
- join
-
See
relational join.
- kriging
-
An interpolation technique
for obtaining statistically unbiased estimates of surface elevations from
a set of control points. Pronounced creeging.
- label
-
A unique name or other
nominal code assigned to identify the geographic representation of a map
feature. It is distinguished from attribute data by serving as the unique
identifier for geographic features (e.g., label: Jones Lake; attributes:
area, depth, water quality).
- label point
-
See
point.
-
Local area network.
Computer data communications technology that connects computers at the
same site. Computers and terminals on a LAN can freely share data and
peripheral devices, such as printers and plotters. LANs are composed of
cabling and special data communications hardware and software.
- Land Information System (LIS)
-
A special type of GIS that
manages and analyzes data related to land ownership (e.g., tax parcels,
urban infrastructure, property assessment). A GIS used for municipal or
county level applications is typically structured as an LIS. Data stored
in an LIS are commonly recorded very accurately on a large-scale map
(e.g., at scales of 1:1,000 to 1:10,000).
- land parcel
-
An area of land for which
rights or ownership and use can be bought.
- Landsat
-
A series of satellites that
produce images of the earth. The Landsat remote sensing satellite program
was developed by NASA (National Aeronautics and Space Administration).
Landsat data are provided in .BIL (band interleaved by line) or .BIP (band
interleaved by pixel) formats. BIL and BIP are supported by ArcInfo and
ArcView.
- land use
-
The classification of land
according to how it is used; for example, agriculture, industrial,
residential, urban, rural, or commercial. Natural features of the land
such as forestry, pastureland, brush land and bodies of water are also
often classifies in this manner.
- large scale
-
A map scale that covers
relatively small area on the ground and has a high level of detail. A
small area of the earth’s surface on one page is a large-scale map (i.e.,
a 1:500 map where 1 map unit equals 500 ground units is large scale
compared with a 1:1,000,000 map). Contrast with small scale.
-
A spherical reference
system used to measure locations on the Earth's surface. Latitude and
longitude are angles measured from the Earth's center to locations on the
Earth's surface. Latitude measures angles in a north-south direction.
Longitude measures angles in the east-west direction.
-
A
surface representation that uses a rectangular array of
mesh
points spaced at a constant sampling interval in the x and y
directions relative to a common origin. A lattice is stored as a grid, but
represents the value of the surface only at the mesh points rather than
the value of the entire
cell.
-
A thematic set of spatial
data described and stored in an ArcStorm database or a LIBRARIAN map
library. Layers organize a database or map library by subject matter
(e.g., soils, roads, and wells). Conceptually, layers in a database or map
library environment are exactly like coverages. See also
ArcStorm database and
map library.
- layer index
-
See
cross-tile indexing.
-
The path, among possibly
many, between two points which has the lowest traversal cost, where cost
is a function of time, distance, or other user-defined factors. See also
impedance.
- left-right topology
-
The topological data
structure ArcInfo uses to represent contiguity between polygons.
Left-right supports analysis functions such as adjacency. See also
topology.
- legend
-
1. The reference area on a
map that lists and explains the colors, symbols, line patterns, shadings,
and annotation used on the map. The legend often includes the scale,
origin, orientation, and other map information.
2. The symbol key used to
interpret a map.
-
A set of software tools to
manage and access large geographic data sets in a
map library. LIBRARIAN commands create and define a map library, move
data in and out of a library, query the data in a map library, and display
the results of a query.
- library
-
A collection of spatially
related ArcStorm or LIBRARIAN layers. A library has a spatial extent which
applies to all layers in the library.
- LIDAR
-
(Light Dectection and
Ranging) - Short light intensity detection and ranging. Lidar uses lasers
to measure distances to reflective surfaces.
- line
-
1. A set of ordered
coordinates that represents the shape of geographic features too narrow to
be displayed as an area at the given scale (e.g., contours, street
centerlines, or streams), or linear features with no area (e.g., state and
county boundary lines).
2. A single
arc
in a coverage.
3. A line on a map (e.g., a
neatline).
- line-in-polygon
-
A spatial operation in
which arcs in one coverage are overlaid with polygons of another coverage
to determine which arcs, or portions of arcs, are contained within the
polygons. Polygon attributes are associated with corresponding arcs in the
resulting line coverage.
-
A symbol for drawing
coverage arcs.
- linear event
-
See
event.
- linear feature
-
A geographic feature that
can be represented by a line or set of lines. For example, rivers, roads
within a pizza delivery area, and electric and telecommunication networks
are all linear features. Linear features are represented in ArcInfo by
arcs or by the route-system feature class.
-
A coverage feature class;
links are two-point segments that represent from- and to-locations for the
rubber sheeting adjustment process.
- literal
-
A string, a number, or a
date which directly represents a constant value. 'XYZ123', '1234' and
'6/10/57' are examples of a string literal, a numeric literal and a date
literal, respectively.
- local area network
-
See LAN.
- log file
-
A coverage or workspace
history file containing a list of all commands used to operate on a
coverage or all commands used in the workspace.
- logical connector
-
One of the reserved words
AND, OR and XOR used to build complex logical
expressions in a query.
-
A combination of items,
system items, system variables, literals and arithmetic logical operators
from which a value of TRUE or FALSE is derived; for example,
$RECNO LE $NUM1
HRS-WRKD * HRLY-WAGE GE 600 AND $MONTH EQ 5
$NUM1 LE 100
- logical operator
-
Another term for Boolean
operator. See
Boolean expression.
-
The process of selecting a
subset of features from a coverage using logical expression that operates
on the attributes of coverage features (e.g., AREA GT 16000). Only those
features whose attributes meet the criteria are selected. Also known as
feature selection by attribute.
-
Long transactions support
applications where changes to a database might span several days, weeks or
months and may involve several sessions. Many planning and design
activities, such as subdivision development, require long transactions.
- longitude
-
See
latitude-longitude.
- lookup table
-
1. A special tabular data
file containing additional attributes for features stored in an associated
feature attribute table. The table can be an external attribute table
or an INFO table that describes coverage features.
2. A special lookup table
in which numeric item values are classified into categories. For example,
well depth can be recorded explicitly in the feature attribute table, but
displayed and used as a set of classes, such as 0 to 250 feet, 251 to 500
feet, and so on. An INFO lookup table contains at least two items: the
relate item and an item named either SYMBOL or LABEL.