arcgis术语表

A
access key
Lets you access the contents of the Main menu from the keyboard by holding down the Alt key and pressing the underlined letter on the menu or menu command item. You create an access key by placing an ampersand (&) in front of the appropriate letter in the command's caption.
active data frame
The data frame in the view that is currently being worked on—for example, the data frame to which layers are being added. The active data frame is shown in bold text in the ArcMap table of contents.
address geocoding
The process of assigning x,y coordinates to addresses so that they can be displayed as points on a map.
address matching
The process of matching address strings to a standardized set of addresses in a street or postal code database.
alias
Another name for a column in a table.
aligned dimension
A dimension that runs parallel to the baseline and represents the true distance between the begin and end dimension points.
altitude
The height, z-value, or vertical elevation of an object above (or below) a given reference datum (for example, sea level).
The height above the horizon (measured in degrees) from which a lightsource illuminates a surface; used when calculating a hillshade or for controlling the position of the lightsource in a scene for on-the-fly shading.
AML
ARC Macro Language. A proprietary high-level algorithmic language for generating end-user applications in ArcInfo Workstation. Features include the ability to create on-screen menus, use and assign variables, control statement execution, and get and use map or page unit coordinates. AML includes an extensive set of commands that can be used interactively or in AML programs (macros), as well as commands that report on the status of ArcInfo environment settings.
analysis
The process of identifying a question or issue to be addressed, modeling the issue, investigating model results, interpreting the results, and possibly making a recommendation. See also model and spatial analysis.
analysis extent
A Spatial Analyst option to set the extent (the x,y coordinates for the bottom-left and top-right corners of the results) for the results from spatial analysis.
analysis mask
A Spatial Analyst option that uses a raster dataset in which all cells of interest have a value and all other cells are nodata. It enables you to perform analysis on a selected set of cells. Processing will only occur on selected cells, with other cells being assigned nodata.
angular units
The unit of measurement on a sphere or a spheroid; usually degrees. Map projection parameters, such as the central meridian and standard parallel, are defined in angular units.
annotation
Descriptive text used to label features. It is used for display, not for analysis.
A feature class used to label other features. Information stored for annotation includes a text string, the location at which the text is displayed, and a text symbol (color, font, size, and so on).
API
Application programming interface. Refers to a defined and documented set of tools or "functions" that application developers use to build or customize a program or set of programs. APIs can be built for programming languages such as C, COM, Java, and so on.
application server
A computer program that receives requests from a client application-another computer program that a user interacts directly with-and returns results to the client. See also client/server and server.
ArcInfo LIBRARIAN
See Map LIBRARIAN.
ArcInfo workspace
A file-based collection of coverages, grids, triangulated irregular networks (TINs), or shapefiles stored as a directory of folders in the file system.
arc–node topology
Arcs represent linear features and the borders of area features in a coverage. Every arc has a from-node, which is the first vertex in the arc, and a to-node, which is the last vertex. Nodes indicate the endpoints and intersections of arcs. They do not exist as independent features. Together they define the direction of the arc. Arc–node topology defines connectivity in coverages—arcs are connected to each other if they share a common node.
ArcPress
A raster printing extension for ArcInfo. ArcPress allows you to easily print ArcInfo maps on a variety of supported raster printers or convert them to a bitmap format for interchange in other graphics applications.
ArcScene
An ArcGISTM application for combining and viewing features, surfaces, and graphics in 3D perspective.
ArcSDE
A gateway to a multi-user commercial RDBMS-for example, Oracle, Microsoft SQL Server, Informix, and DB2. ArcSDE is an open, high-performance spatial data server that employs client/server architecture to perform efficient spatial operations and manage large, shared geographic data. Was known as SDE before 1999.
ArcSDE for Coverages
An ArcSDE server that provides read-only access to ArcInfo coverages, shapefiles, ArcStorm library layers, and Map LIBRARIAN layers. Uses the same data transfer technology as ArcSDE for RDBMS servers.
ArcStorm
ArcStorm (Arc Storage Manager) is a data storage facility and transaction manager for ArcInfo file-based coverage data. ArcStorm manages a feature-oriented database that can be closely integrated with an RDBMS. Transaction management occurs via feature locking.
ArcStorm database
A collection of libraries, layers, INFO tables, and external database management system (DBMS) tables. Data stored in an ArcStorm database benefits from the transaction management and data archiving capabilities of ArcStorm.
area
The planimetric view of a polygon feature or surface.
The surface area of a 3D surface, or of the portion of a surface above or below a reference plane. Surface is measured along the slope of a surface and is always greater than the 2D planimetric extent of the surface. When compared to planimetric area, surface area gives you an idea of the surface roughness.
arithmetic functions
Functions within the Raster Calculator of Spatial Analyst.
There are six arithmetic functions: Abs, Ceil, Floor, Int, Float, and IsNull.
The Abs function takes the absolute value of the values in an input grid.
Ceil and Floor convert floating-point values into integers by rounding up or down, respectively.
Int and Float convert values from and to integer and floating-point values.
The IsNull function returns 1 if the values on the input grid are nodata or null, and 0 if they are not.
arithmetic operators
Operators within the Raster Calculator of the Spatial Analyst. They allow for the addition, subtraction, multiplication, and division of two grids, numbers, or a combination of the two.
 

aspatial query
See attribute query and query.
aspect
The direction a slope faces. The aspect recorded for a TIN face is the steepest downslope direction of the face. The slope at a cell in a raster is the steepest downslope direction of a plane defined by the cell and its eight surrounding neighbors.
attribute
A piece of information describing a map feature. The attributes of a census tract, for example, might include its area, population, and average per capita income.
A characteristic of a geographic feature described by numbers, characters, images, and CAD drawings, typically stored in tabular format and linked to the feature by a user-assigned identifier. For example, the attributes of a well might include depth and gallons per minute.
A column in a table.
attribute domain
A named constraint in the database. An attribute domain is used to constrain the values allowed in any particular attribute for a table, feature class, or subtype. An attribute domain can be shared across feature classes and tables in a geodatabase. Types of attribute domains include range and coded value domains.
attribute query
A query of attributes in a table or feature class. Also called aspatial query. See also query.
attribute table
A DBMS or other tabular file containing rows and columns. In ArcInfo, attribute tables are associated with a class of geographic features (for example, wells or roads). Each row represents a geographic feature. Each column represents one attribute of a feature. See also feature attribute table.
Attributes dialog box
A dialog box that lets you view and edit attributes of features you've selected in ArcMap.
autocorrelation
The statistical relationship among the measured points, where the correlation depends on the distance and/or direction that separates the locations.
Automation
A feature of the COM technology. It lets you access ArcObjects in VB and in other languages, tools, and applications that support automation. For example, with VB you can access the data in and properties of the selected item in the Catalog tree.
azimuth
A horizontal direction measured as the angular distance between true north and an object. Often used to define an oblique cylindrical projection or the angle of a geodesic between two points.
A compass direction. In 3D Analyst and Spatial Analyst, the direction from which a lightsource illuminates a surface is called the azimuth.
azimuthal projection
A form of projection in which the earth is projected onto a conceptual tangent or secant plane. See also planar projection.

B
background
You can set the color of the background of a scene to suggest sky, empty space, or any color that suits your visualization purpose. The default background color is white.
Some rasters (typically images) have border areas that are outside of the area for which image data was collected. This area is often assigned an arbitrary value (often black, or 255). You can control the display of these parts of a raster by setting the background color on the Symbology tab of the Layer Properties dialog box. See also nodata.
backup
A copy of a file, a set of files, or an entire disk for safekeeping in case the original is lost or damaged.
band
A measure of a characteristic or quality of the features observed in a raster. Some rasters have a single band; others have more than one. For example, satellite imagery commonly has multiple bands representing different wavelengths of energy along the electromagnetic spectrum.
barrier
An object that is placed on a map to specify the point in a network past which a trace cannot continue.
A line that limits the search for input sample points when performing interpolation. The line can represent a cliff, ridge, or some other interruption in the landscape. Only the sample points on the same side of the barrier as the current processing cell will be considered.
base height
The height at which a surface, raster, or feature draws in a scene. You can set the base height for features and rasters from a surface or by using a constant value or expression. Features with z-values stored in their geometry can have their base height set using the z-values. Setting the base heights from a surface is also called draping.
batch mode operation
Operates a given ArcToolbox tool to process a set of information, or a batch, rather than applying the tool to one piece at a time.
batch table
Displays the input name, user-selected parameters, and output name, where applicable, for all batch entries in ArcToolbox.
behavior
Properties of an object in a geodatabase that describe how it can be edited and drawn. Behavior includes, but is not limited to, validation rules, subtypes, default values, and relationships.
bin
A classification of lags in which all lags that have similar distance and direction are put into the same bin. Bins are commonly formed by dividing the sample area into grid cells or sectors.
BLOB
Binary large object. The binary data type of a column in an RDBMS table that stores large image, text, or geometry data as attributes.
bookmark
See spatial bookmark.
Boolean expression
A type of expression that reduces to a true or false (logical) condition. A Boolean expression contains logical expressions (for example, DEPTH > 100) and Boolean operators.
Boolean operator
A keyword that specifies how to combine simple logical expressions to define a complex expression. Boolean operators include AND, NOT and OR. For example, DEPTH>100 AND DIAMETER>20.
Operators within the Raster Calculator of Spatial Analyst. They use Boolean logic (TRUE or FALSE) on the input grids on a cell-by-cell basis. Output values of TRUE are written as 1, and values of False are written as 0.
Boolean operators: and, or, xor, not. For example: ingrid1 or ingrid2.
breakline
A line that marks a change in the shape of a surface. See TIN.
buffer
A zone of a specified distance around features. Both constant- and variable-width buffers can be generated. Buffers are useful for proximity analysis (for example, find all stream segments within 300 feet of a proposed logging area).
button
A command that runs a macro or custom code when clicked. Buttons can be added to any menu or toolbar. When they appear in a menu, buttons are referred to as menu commands.

C
CAD
See computer-aided design.
CAD dataset
A feature dataset representation of a CAD drawing. A CAD feature dataset is composed of feature classes representing all the points, lines, polygons, or annotation in the CAD drawing. For example, a CAD drawing may contain two line layers representing roads and parcel boundaries, respectively. The CAD dataset's line feature class represents all features in both the road and parcel boundary layers. A CAD dataset can contain wld files to put CAD drawings and data in geographic units rather than page units.
CAD drawing
The digital equivalent of a drawing, figure, or schematic created using a CAD system—for example, a drawing file or DWG file in AutoCAD.
An item in the Catalog tree representing all features and annotation in a CAD file. When you add a CAD drawing to a map or preview its contents in ArcCatalog, features are drawn using the symbology defined in the CAD file.
CAD feature class
A feature class in a CAD dataset. A CAD feature dataset is comprised of feature classes representing all the points, lines, polygons, or annotation in the CAD drawing. For example, a CAD drawing may contain two line layers representing roads and parcel boundaries, respectively. The CAD dataset's line feature class represents all features in both the road and parcel boundary layers.
candidates
A record from a geocoding reference data source that is a potential match for an address.
caption
The text for a command that appears with the "Text Only" and "Image and Text" display types-for example, the name of a menu or menu commands.
cardinality
A property of a relationship. Cardinality describes how many objects of type A are associated with how many objects of type B. Relationships can have many-to-one, one-to-one, one-to-many, and many-to-many cardinalities.
CASE
Computer-Aided Software Engineering. Consists of tools and techniques that automate the process of developing software systems or schemas. Complex tasks that often require many lines of code are simplified with CASE user interfaces and code generators.
Catalog tree
Contains a set of folder connections in ArcCatalog that provide access to geographic data stored in folders on local disks or shared on the network. It also includes folders that let you manage database connections and coordinate systems. The Catalog tree provides a hierarchical view of the geographic data in those folders.
categorical raster
A raster that represents the world with a set of values that have been aggregated into classes. For example, a satellite image that has been reclassified to extract a number of landcover types is a categorical raster. Categorical rasters represent an area, but the values do not form a continuous surface. See raster.
cell
Also known as raster cell or grid cell. A discretely uniform unit (square or rectangle) that represents a portion of the earth such as a square meter or square mile. Each grid cell has a value that corresponds to the feature or characteristic at that site such as a soil type, census tract, or vegetation class.
cell size
The length in map units of the side of a cell of a raster. The cell size is the same in both the x and y directions.
cell statistics
A Spatial Analyst function that calculates a statistic for each cell of an output raster that is based on the values in the same cell location of each cell of multiple input rasters.
central meridian
The line of longitude that defines the center and often the x origin of a projected coordinate system.
chart
A graphic representation of tabular data. Also referred to as a graph.
circle
A geometric shape for which the distance from the center to any point on the edge is equal.
class
A group or category of attribute values.
The interface by which an application program accesses the operating system and other services.
classifying
The process of sorting or arranging attribute values into groups or categories; all members of a group are represented on the map by the same symbol.
client/server
A software system is said to have a client/server architecture when there is a central process (server) that accepts requests from multiple user processes called clients.
cluster tolerance
The distance range in which all vertices and boundaries in a shapefile or feature dataset are considered identical, or coincident. A user-specified tolerance for the Integrate command in ArcMap. For example, if the cluster tolerance is set to 10 map units, after running Integrate there will be no more than one vertex within 10 map units of another.
coded value domain
Specifies a valid set of values for an attribute. Can apply to any kind of attribute—text, numeric, date, and so on. See also attribute domain.
coincident
Vertices or boundaries are coincident when they are within the cluster tolerance of one another. See also cluster tolerance.
color ramp
A range of colors used in a map to show ranking or order of feature attributes.
column
The vertical dimension of a table. A column has a name and a data type applied to all values in the column. See also item, field, and attribute.
COM
Component Object Model. The Component Object Model is a technology, not a programming language. COM is a binary specification from Microsoft that establishes a common way of building software components. COM objects have interfaces that contain methods and properties.
COM object
An object that implements its methods and properties through interfaces. COM objects behave as servers that interact with clients through one or more interfaces. Client code grabs a COM object's interface and tells that object to perform a function or manipulate a property. COM components can be dynamically interchanged in a distributed system with Dynamic Link Libraries (DLLs are in-process servers) and executable programs (EXEs are out-of-process servers).
combo box
A user interface tool that combines the features of an edit box and a list box. A combo box lets you type information or choose an option from a list. For example, the Location combo box in ArcCatalog lets you select an item in the Catalog tree by typing its path or choosing a path from its dropdown list.
command
An instruction that, when issued by the user, causes an application to perform an action. A command can be typed on a keyboard, chosen from a menu or toolbar, or embedded in program code.
complex edge feature
In a geodatabase, a linear network feature that corresponds to one or more network elements in the logical network. See also simple edge feature.
complex junction feature
In a geodatabase, a junction feature that corresponds to more than one network element in the logical network. For example, the state of the junction determines whether features can be connected or disconnected. See also simple junction feature.
composite relationship
Composite relationships describe associations where the lifetime of one object controls the lifetime of its related objects. An example is the association between highways and points for placing a highway shield marker. Shield points can't exist without a highway. See also relationship and simple relationship.
compress
The process of removing all database states that are no longer referenced by a version, and moving all rows in the delta tables (which are common to all versions) to the base table in a multiversioned geodatabase.
computer-aided design (CAD)
An automated system for the design, drafting, and display of graphically oriented information. Also known as computer-aided drafting.
concurrency management
A database management process for maintaining the consistency of the data while supporting simultaneous access by more than one user. A typical technique is to use a system of locking data to prevent data corruption caused by multiple users concurrently editing and reading data.
conflict
When multiple users simultaneously edit a version or reconcile two versions, conflicts can occur. Conflicts occur when the same feature or topologically related features are edited in both the edit and reconciliation versions, and the database is unclear about which representation is valid. See also conflict resolution.
conflict resolution
The process of resolving conflicting edits in two versions of the same dataset. Resolving a conflict requires that you make a conscious decision about the feature's correct representation and identify it in the Conflict Resolution dialog box. See also conflict.
conformal projection
A projection on which all angles at each point are preserved. Also called an orthomorphic projection (Snyder and Voxland, 1989). See also tangent projection and secant projection.
conic projection
A projection resulting from the conceptual projection of the earth onto a tangent or secant cone, which is then cut lengthwise and laid flat (Snyder and Voxland, 1989). See also tangent projection and secant projection.
connection
A mechanism in ArcCatalog used to access remote file systems and shared databases. Users establish connections to access remote or shared information.
connectivity
In a geodatabase, the state of edges and junctions in a logical network that controls flow, tracing, and pathfinding.
The topological identification in a coverage of connected arcs by recording the from-node and to-node for each arc. Arcs that share a common node are connected. See also arc–node topology.
connectivity rules
In a geodatabase, network rules that constrain the type of network features that may be connected to one another, and the number of features of any particular type that can be connected to features of another type. In most networks, not all edge types can logically connect to all junction types. Similarly, not all edge types can logically connect to all other edge types through all junction types. There are two types of connectivity rules: edge–junction and edge–edge.
constraints
Limits imposed on a model to maintain data integrity. For example, in a water network model, an 8-inch pipe can't connect to a 4-inch pipe.
Content Standard for Digital Geospatial Metadata
A metadata style guide authored by the FGDC. All U.S. government agencies (federal, state, and local) that receive federal funds to create metadata must create metadata following this standard.
contiguity
In coverages, the topological identification of adjacent polygons by recording the left and right polygons of each arc. See also polygon-arc topology.
continuous raster
A raster that represents the world with a set of values that vary continuously to form a surface. For example, a raster digital elevation model and an interpolated chemical concentration surface are continuous rasters.
contour
A line that connects points of equal value on a terrain surface (an isoline).
control points
Points you establish on a paper map whose coordinates represent known ground points or specific locations. Control points are used to register a paper map before you begin digitizing features on it using a digitizer.
conversion
A Spatial Analyst function. The process of converting input data from one representation to another, such as raster to vector.
coordinate
A set of numbers that designate location in a given reference system, such as x,y in a planar coordinate system or x,y,z in a three-dimensional coordinate system. Coordinate pairs represent a location on the earth's surface relative to other locations. See also vector.
coordinate system
A reference system used to measure horizontal and vertical distances on a planimetric map. A coordinate system is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y-directions to locate x,y positions of point, line, and area features.
In ArcInfo, a system with units and characteristics defined by a map projection. A common coordinate system is used to spatially register geographic data for a given area.
A reference system consisting of a set of points, lines, and/or surfaces, and set of rules used to define the positions of points in space either in two or three dimensions.
cost grid
An input dataset necessary to run the cost weighted distance function using Spatial Analyst. It identifies the cost of traveling through each cell in the grid. The Cost Weighted Distance function uses this cost grid to calculate the accumulative cost of traveling from every cell in the grid to a source or a set of sources.
Cost Weighted Allocation
A Spatial Analyst function that identifies the nearest source from each cell in a cost weighted distance grid. Each cell is assigned to its "nearest" source cell, in terms of accumulated travel cost.
Cost Weighted Direction
A Spatial Analyst function that provides a road map from the Cost Weighted Distance grid, identifying the route to take from any cell, along the least-cost path, back to the nearest source.
Cost Weighted Distance
A Spatial Analyst function that uses a cost grid to assign a value—the least accumulative cost of getting back to the source—to each cell of an output grid.
coverage
A file-based vector data storage format for storing the location, shape, and attributes of geographic features. A coverage usually represents a single theme such as soils, streams, roads, or land use. It is one of the primary vector data storage formats for ArcInfo. A coverage stores geographic features as primary features (such as arcs, nodes, polygons, and label points) and secondary features (such as tics, map extent, links, and annotation). Associated feature attribute tables describe and store attributes of the geographic features.
coverage units
The units (for example, feet, meters, inches) of the coordinate system in which a coverage is stored.
current task
During editing in ArcMap, a setting in the Current Task dropdown list that determines the task with which the sketch construction tools (Sketch, Arc, Distance-Distance, and Intersection) will work. The current task is set by clicking a task in the Current Task dropdown list.
custom behavior
Behavior is the implementation of an object class method. ESRI-provided objects have a set of methods associated with them. A developer can choose to override one of these methods or create additional methods. In this instance, the object is said to have custom behavior.
custom feature
In geodatabases, a feature with specialized behavior instantiated in a class by a developer.
custom tool
In ArcToolbox, a tool created by a user and added to the My Tools toolset.
custom toolset
A folder created by a user to hold custom tools or a group of frequently used ArcToolbox tools. It is created and stored with the ArcToolbox My Tools toolset.
cylindrical projection
A projection resulting from the conceptual projection of the earth onto a tangent or secant cylinder, which is then cut lengthwise and laid flat (Snyder and Voxland, 1989). See also tangent projection and secant projection.

D
dangle tolerance
The minimum length allowed for dangling arcs in coverages in ArcInfo's Clean process. Clean removes dangling arcs that are shorter than the dangle tolerance. Also known as the dangle length.
dangling arc
An arc having the same polygon on both its left and right sides and having at least one node that does not connect to any other arc. It often occurs where a polygon does not close properly (undershoot), where arcs don't connect properly, or where an arc was digitized past its intersection with another arc (overshoot). A dangling arc is not always an error. For example, dangling arcs can represent cul-de-sacs in street centerline maps.
data
A collection of related facts usually arranged in a particular format and gathered for a particular purpose.
data dictionary
A set of tables containing information about data. ArcSDE and the geodatabase have data dictionary tables containing information about the GIS data in the database.
data frame
In ArcMap, a frame on the map that displays layers occupying the same geographic area. You may have one or more data frames on your map depending on how you want to organize your data. For instance, one data frame might highlight a study area and another might provide an overview of where the study area is located.
data integrity
Refers to the accuracy and consistency of data in a database. Data integrity is maintained through the creation of attribute domains and through mandatory conflict resolution between versions of a dataset.
data model
See georelational data model and geodatabase data model.
data source
Geographic data (coverage, shapefile, raster, or feature class) in a geodatabase.
data type
The attribute of a variable or field (column) that determines the kind of data it can store. Common data types are character, integer, decimal, single, double, and string.
data view
An all-purpose view in ArcMap for exploring, displaying, and querying geographic data. This view hides all map elements such as titles, North arrows, and scale bars. See also layout view.
database
A collection of related data organized for efficient retrieval of information.
A logical collection of interrelated information managed and stored as a unit, usually on some form of mass storage system such as magnetic tape or disk. A GIS database includes data about the spatial location and shape of geographic features recorded as points, lines, areas, pixels, grid cells, or TINs, as well as their attributes.
database administrator
One who manages a database—sets up users, security, backup, and recovery procedures for all data and optimizes physical data storage for best performance.
database connection
A connection in ArcCatalog to a database. Database connections have a state—they are either connected to or disconnected from the database. If you delete a database connection, you only delete the connection itself, not the database or its contents. In general, when you create a database connection, you choose a data provider that will retrieve your data from the appropriate database. To work with the features in a multiuser geodatabase, use ArcSDE as the data provider. OLE DB providers let you access data in many different databases.
database management system
See DBMS.
dataset
Any feature class, table, or collection of feature classes or tables in the geodatabase.
A named collection of logically related data items arranged in a prescribed manner.
datum
A set of parameters and control points used to accurately define the three-dimensional shape of the earth. The datum defines part of a geographic coordinate system that is the basis for a planar coordinate system. For example, the North American Datum for 1983 (NAD83) is the datum for map projections and coordinates within the United States and throughout North America.
datum transformation
See geographic transformation.
DBMS
Database management system. A set of computer programs for organizing the information in a database. A DBMS supports the structuring of the database in a standard format and provides tools for data input, verification, and storage.
decimal degrees
Degrees of latitude and longitude expressed in decimal format rather than in degrees, minutes, and seconds.
default junction type
In geometric networks, two edge types may be connectable through more than one junction type. You can establish which of those junction types is the default for connecting the two edge types. This junction type is the default junction type. An edge may also have a default end junction type. This is the junction that is used for the free ends of new edges.
degree slope
One of the ways slope is measured (measured from 0󈟆 degrees).
DEM
Digital elevation model.
A digital representation of a continuous variable over a two-dimensional surface by a regular array of z-values referenced to a common datum. Digital elevation models are typically used to represent terrain relief. Also referred to as digital terrain model (DTM).
An elevation database for elevation data by map sheet from the National Mapping Division of the U.S. Geological Survey (USGS).
The format of the USGS digital elevation datasets.
density
A Spatial Analyst function that distributes the quantity or magnitude of point or line observations over a unit of area to create a continuous raster— for example, population per square kilometer.
destination
The secondary object in a relationship. For example, a table containing attributes that are associated with features in a feature class. See also relationship and origin.
The destination point for a path when performing the Shortest Path function with Spatial Analyst.
determinate flow direction
For an edge feature, occurs when the flow direction can be determined from the topology of the network, the locations of sources and sinks, and the enabled or disabled states of features.
digitizing
To encode geographic features in digital form as x,y coordinates.
The process of converting the features on a paper map into digital format. When you digitize a map, you use a digitizing tablet, or digitizer, which is connected to your computer. You then trace over features with a digitizer puck, which is similar to a mouse. The x,y coordinates of these features are automatically recorded and stored as spatial data.
Heads-up digitizing features from on-screen data (rasters, for example).
digitizing mode
Also called absolute mode, digitizing mode is one of the ways in which a digitizing tablet operates. In digitizing mode, the location of the tablet is mapped to a specific location on the screen. Moving the digitizer puck on the tablet surface causes the screen pointer to move to precisely the same position. See also mouse mode.
dimension construction methods
Dictate what type of dimension feature is created and the number of points required to complete the feature's geometry. Construction methods include simple aligned, aligned, linear, rotated linear, free aligned, and free linear.
dimension feature
A special kind of map annotation that shows specific lengths or distances on a map. A dimension feature may indicate the length of a side of a building or land parcel, or it may indicate the distance between two features such as a fire hydrant and the corner of a building. Dimension features are stored in a dimension feature class.
dimension feature class
In the geodatabase, dimension features are stored in a dimension feature class. Like other feature classes in the geodatabase, all features in a dimension feature class have a geographic location and attributes and can either be inside or outside of a feature dataset.
dimension style
A dimension feature's style describes its symbology, what parts of it are drawn, and how it is drawn. Every time you create a new dimension feature, it is assigned a particular style. A collection of dimension styles is associated with a dimension feature class.
dimensioning toolbar
A toolbar in ArcMap that facilitates the creation of dimension features.
direct connect
A two-tiered architecture for connecting to a spatial database. Direct connect does not require the ArcSDE application server to connect to a spatial database.
directory
A computer term identifying a location on a disk containing a set of files and other directories (subdirectories). Operating systems use directories to organize data. The location of a directory is specified with a path. Also called folder. See also folder.
disabled feature
A network feature through which flow is impossible.
discrete raster
A rater that typically represents phenomena that have clear boundaries and attributes that are descriptions or categories. Each cell in a discrete raster stores an integer value that represents a feature. In a grid of land cover, for example, the value 1 might represent forested land, the value 2 urban land, and so on. See also categorical raster.
disk
A storage medium consisting of a spinning disk coated with a magnetic material for recording digital information.
display type
Controls whether you see a command's image, its caption, or both when it appears on a toolbar or in a menu.
display units
The units—for example, feet, miles, meters, or kilometers—ArcMap uses to report measurements, dimensions of shapes, and distance tolerances and offsets.
DLL
See dynamic link library.
documentation
Text in an item's metadata describing where the data came from, attribute definitions, and so on. Unlike properties, which are automatically derived from the data source, documentation must be manually entered using the metadata editor in ArcCatalog.
domain
See attribute domain and spatial domain.
double precision
Refers to a high level of coordinate accuracy based on the possible number of significant digits that can be stored for each coordinate. ArcInfo datasets can be stored in either single or double precision. Double-precision coverages store up to 15 significant digits per coordinate (typically 13 to 14 significant digits), retaining the accuracy of much less than one meter at a global extent. See also single precision.
drape
To set the base height for features of a surface using a surface. When you drape a layer over a raster surface, the resolution of the base surface is automatically downsampled to increase performance. You can change the resolution of the base surface if the default is unsatisfactory.
drawing priority
The order in which layers that occupy the same x,y,z positions are drawn in a scene. For example, if you have a road feature layer and an orthophoto draped over the same terrain model, the roads and raster may appear patchy or broken-up where they coincide. You can reduce the drawing priority for the raster so it will appear below the features. You can only change the drawing priority for areal features and surfaces.
dynamic link library (DLL)
Modules containing a set of routines that are called from procedures. A DLL is loaded and linked to your application at runtime by its calling modules (EXE or DLL).

E
eccentricity
A measurement of how much an ellipse deviates from a true circle. Measured as the square root of the quantity [(1-b2/a2)1/2], or 1.0 minus the square of the ratio of the semiminor axis to the semimajor axis. The square of the eccentricity, "e2", is commonly used with the semimajor axis, "a", to define a spheroid in map projection equations.
edge
The linear segments between nodes in a TIN surface. Edges store information about the faces that they border. Linear features and the perimeters of polygon features used to generate a TIN become edges in the TIN.
edge element
A network feature that has a length through which commodity flows. See also logical network.
edge–edge rule
In geodatabases, a connectivity rule that establishes that an edge of type A may connect to an edge of type B through a junction of type C. Edge–edge rules always involve a junction type.
edge–junction cardinality
A rule may exist that allows an edge of type A to connect to a junction of type B. By default, any number of edges of type A can connect to a single junction of type B. You may want to restrict this. You can specify that between two and five edges of type A can connect to a junction of type B, but if there are less than two edges, or more than five edges, the connectivity rule is being violated. Similarly, you can restrict the number of junctions of type C that can connect to any junction of type D. This range of permissible connections is edge–junction cardinality.
edge–junction rule
A connectivity rule in geodatabases establishing that an edge of type A may connect to a junction of type B.
edit box
A command that displays text typed by a person or derived from another source. For example, in ArcMap you can type the scale at which you want to see the map. Also known as a text box.
edit cache
A setting used in spatial data editing in ArcMap that causes the features visible in the current map extent to be held in memory on your local machine. Designed to be used when working with large amounts of data, an edit cache results in faster editing because ArcMap doesn't have to retrieve the data from the server.
edit session
In ArcMap, all editing takes place within an edit session. An edit session begins when you choose Start Editing from the Editor menu and ends when you choose Stop Editing.
Editor toolbar
A set of tools that allows you to create and modify features and their attributes in ArcMap.
element
See map element.
ellipse
A geometric shape equivalent to a circle that is viewed obliquely; a flattened circle.
ellipsoid
When used to represent the earth, the three-dimensional shape obtained by rotating an ellipse about its minor axis. This is an oblate ellipsoid of revolution, also called a spheroid.
ellipticity
The degree to which an ellipse deviates from a true circle. The degree of flattening of an ellipse, measured as 1.0 minus the ratio of the semiminor axis to the semimajor axis.
enabled feature
In geodatabases, a network feature that allows flow to pass through it.
enclosures
Files describing the contents of a data source can be enclosed in the metadata. A copy of the file is contained within the metadata. Enclosing files in metadata works the same way as enclosing files in an e-mail message.
equal area projection
A projection on which the areas of all regions are shown in proportion to their true areas. Shapes may be greatly distorted (Snyder and Voxland, 1989). See also conformal projection.
equator
The parallel of reference that defines the origin of latitude values, 0 degrees north or south.
equatorial aspect
A planar projection with its central point located at the equator.
equivalent projection
A projection that maintains scale along one or more lines, or from one or two points to all other points on the map. Also called equidistant projection. See also conformal projection.
erase
An ArcInfo command that erases the input coverage features that overlap the erase coverage polygons.
Euclidean distance
See straight line distance.
event
Objects execute code in response to an event. Events occur when the user interacts with an application. For example, clicking a button closes a form. The event triggered by clicking the button is the form closing.
executable (EXE)
A program file created from one or more source code files translated into machine code and linked together.
exit state
The condition of a tool upon closure. If a tool fails due to a programming bug or command failure, the exit state will be "failed".
extent
The coordinate pairs defining the minimum bounding rectangle (xmin, ymin and xmax, ymax) of a data source. All coordinates for the data source fall within this boundary.
extent rectangle
A rectangle that is displayed in one data frame, showing the size and position of another data frame.
Extract wizard
An ArcToolbox wizard that selects features from a coverage based on attribute values to create a new coverage.
extrusion
You can extrude 2D point, line, and area features in a scene into lines, planes, and solids. Use extrusion to show the depth of well point features or the height of building footprint polygons.

F
face
Triangles form the faces on a TIN surface. Each face on a TIN surface is defined by three edges and three nodes, and is adjacent to one to three faces on the surface. TIN faces store aspect and slope information and may have tag values.
false easting
A linear value added to the x-values, usually to ensure that all map coordinates are positive. See also false northing.
false northing
A linear value added to the y-values, usually to ensure that all map coordinates are positive. See also false easting.
feature
An object class in a geodatabase that has a field of type geometry. Features are stored in feature classes.
A representation of a real-world object.
A point, line, or polygon in a coverage, shapefile, or geodatabase feature class.
feature attribute table
A table used to store attribute information for a specific coverage feature class. ArcInfo maintains the first several items of these tables. Feature attribute tables supported for coverages include the following:
<cover>.PAT for polygons or points
<cover>.AAT for arcs
<cover>.NAT for nodes
<cover>.RAT for routes
<cover>.SEC for sections
<cover>.PAT for regions
<cover>.TAT for annotation (text) where <cover> is the coverage name.
feature class
The conceptual representation of a geographic feature. When referring to geographic features, feature classes include point, line, area, and annotation. In a geodatabase, an object class that stores features and has a field of type geometry.
A classification describing the format of geographic features and supporting data in a coverage. Coverage feature classes for representing geographic features include point, arc, node, route-system, route, section, polygon, and region. One or more coverage features are used to model geographic features; for example, arcs and nodes can be used to model linear features such as street centerlines. The tic, annotation, link, and boundary feature classes provide supporting data for coverage data management and viewing.
The collection of all the point, line, or polygon features or annotation in a CAD dataset.
feature dataset
In geodatabases, a collection of feature classes that share the same spatial reference. Because the feature classes share the same spatial reference, they can participate in topological relationships with each other such as in a geometric network. Several feature classes with the same geometry may be stored in the same feature dataset. Object classes and relationship classes can also be stored in a feature dataset.
FGDC
Federal Geographic Data Committee. An interagency committee, organized in 1990, that promotes the coordinated use, sharing, and dissemination of geospatial data on a national basis. The FGDC is composed of representatives from 16 Cabinet-level and independent U.S. federal agencies. The FGDC authored the Content Standard for Digital Geospatial Metadata.
field
A column in a table. Each field contains the values for a single attribute.
file
A set of related information that a computer can access by a unique name (for example, a text file, a data file, a DLG file). Files are the logical units managed on disk by the computer's operating system. Files may be stored on tapes or disks.
file type
Files that are not geographic data sources can appear in ArcCatalog if they have been added to the file types list. A file type consists of a description of the file's format (such as "Text Document"), the file extension associated with this type of file (such as ".txt"), and the icon used to represent these files.
flag
In ArcMap, an object that is placed on a network to specify the starting point for a trace task.
flattening
A measure of how much a spheroid differs from a sphere. The flattening is the ratio of the semimajor axis minus the semiminor axis to the semimajor axis. Known as "f" and often expressed as a ratio. Example: 1/298.3. Also known as the ellipticity.
flow direction
The direction in which commodities flow through edge elements in a network.
focal functions
This group of Spatial Analyst functions computes an output raster where the output value at each location is a function of the input cells in some specified neighborhood of the location.
folder
A location on a disk containing a set of files and other folders. See also directory.
folder connection
A top-level branch of the Catalog tree in ArcCatalog that provides quick access to a location in the file system. You can make connections to hard drives, folders, and geodatabases.
foreign key
A column or combination of columns in one table whose values match the primary key in another table. A value in the foreign key can only exist if there is a corresponding value in the primary key (unless the value is NULL). Foreign key–Primary key relationships define a relational join.
Used to create a relationship class, the foreign key resides in the destination object class. To join two object classes together, the primary key and foreign key must share the same values.
See also primary key, relate, and relationship class.
format
The pattern into which data is systematically arranged for use on a computer. A file format is the specific design of how information is organized in the file. For example, ArcInfo has specific, proprietary formats used to store coverages. DLG, DEM, and TIGER are geographic datasets with different file formats.
freeze
When exploring a table's contents, you can fix a column in place at the left side of the table. When you scroll horizontally through the table's columns, the frozen column stays in place while the other columns scroll normally. For example, freeze the "Country_name" column so it's easy to see which country has which population or birth rate.
function
See spatial function.
fuzzy tolerance
An extremely small distance used to resolve inexact intersection locations due to the limited arithmetic precision of computers. It defines the resolution of a coverage resulting from the Clean operation or a topological overlay operation such as Union, Intersect, or Clip.

G
Gauss-Krüger
A projected coordinate system used in Europe that divides the area into zones six degrees wide. Very similar to the UTM coordinate system.
geocentric latitude
Defined as the angle between the equatorial plane and a line from a point on the surface to the center of the sphere or spheroid.
geocoding
The process of creating geometric representations for locations (such as point features) from descriptions of locations (such as addresses).
geocoding index
An index on geocoding reference data used by geocoding services.
geocoding reference data
Data that a geocoding service uses to determine the geometric representations for locations.
geocoding service
An object that defines a process for creating geometric representations for locations (such as point features) from descriptions of locations (such as addresses).
geodatabase
An object-oriented geographic database that provides services for managing geographic data. These services include validation rules, relationships, and topological associations. A geodatabase contains feature datasets and is hosted inside of a relational database management system.
geodatabase data model
Geographic data model that represents geographic features as objects in an object-relational database. Features are stored as rows in a table; geometry is stored in a shape field. Supports sophisticated modeling of real-world features. Objects may have custom behavior.
geodesic
The shortest distance between two points on the surface of a spheroid. Any two points along a meridian form a geodesic. See also great circle.
geodetic latitude
Defined as the angle formed by the perpendicular to the surface at a point and the equatorial plane. On a spheroid, the perpendicular doesn't intersect the center of the spheroid in the equatorial plane.
geographic coordinate system
A reference system using latitude and longitude to define the locations of points on the surface of a sphere or spheroid. See also projected coordinate system.
geographic coordinates
A measurement of a location on the earth's surface expressed in degrees of latitude and longitude. See also projected coordinates.
geographic data
The locations and descriptions of geographic features. The composite of spatial data and descriptive data.
geographic database
A collection of spatial data and related descriptive data organized for efficient storage and retrieval by many users.
geographic transformation
A method that converts data between two geographic coordinate systems (datums). Also known as a datum transformation.
geolocation
The process of creating features from tabular data by matching the tabular data to a spatial location. Examples of geolocation is creating point features from a table of x,y coordinates, addresses, and linear events. Points can be created by matching addresses to streets.
geometric network
Represents a one-dimensional linear network such as a road system, a utility network, or a hydrologic network. Geometric networks contain feature classes that play a topological role in the network. These feature classes are homogeneous collections of one of these four network feature types: simple junction feature, complex junction feature, simple edge feature, and complex edge feature. More than one feature class can have the same type of network feature.
geoprocessing
GIS operations such as geographic feature overlay, coverage selection and analysis, topology processing, and data conversion.
Geoprocessing Server
A UNIX or Windows NT computer that handles geoprocessing tasks remotely. It includes a utility to schedule remote processing.
georeference
The process of defining how raster data is situated in map coordinates. Georeferencing raster data allows it to be viewed, queried, and analyzed with other geographic data.
georelational data model
A geographic data model that represents geographic features as an interrelated set of spatial and descriptive data. The georelational model is the fundamental data model used in coverages—for example, it pulls together geometry and attributes that are stored in different places.
Geospatial Data Clearinghouse
Sponsored by the FGDC. A decentralized system of servers on the Internet that contain metadata describing available geographic data. This metadata follows the format specified by the Content Standard for Digital Geospatial Metadata to facilitate querying and enforce a consistent presentation across all servers.
GIS
Geographic information system. An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.
A GIS may be used for a project (also called project GIS, or single-user GIS), by a department of an organization to support a key function of that department (called departmental GIS), or by an organization to support daily activities and strategic decision making (called enterprise GIS).
global functions
This group of Spatial Analyst functions computes an output raster where the output value at each location is potentially a function of all the cells in the input raster.
graticule
A graphic representation on a map of the network of parallels and meridians (latitude and longitude) that subdivide the earth's surface.
great circle
Any circle on the surface of a sphere formed by the intersection of the surface with a plane passing through the center of the sphere. The shortest path between any two points lies on a great circle and is therefore important to navigation. All meridians and the equator are great circles on the earth defined as a sphere (Snyder and Voxland, 1989). See also geodesic.
Greenwich prime meridian
The prime meridian located in Greenwich, England. A prime meridian defines the origin of longitude values.
grid
A geographic representation of the world as an array of equally sized square cells arranged in rows and columns. Each grid cell is referenced by its geographic x,y location. See raster.
grid cell
See raster cell.
ground control point
A location of known x,y coordinates used to georeference a raster. A ground control point links a location on a raster to a location in map coordinates.
group layer
Several layers that appear and act like a single layer in the table of contents in ArcMap.

H
Help Node
A branch in the ArcToolbox tree providing overview Help for ArcToolbox toolsets.
hillshade
The hypothetical illumination of a surface. A hillshade raster can be calculated for a given surface, or hillshading can be applied on the fly to surfaces and areal features in a scene.
histogram
A Spatial Analyst function that creates a histogram from the values in a raster dataset. By default, the value field is represented on the x-axis and the number of cells with this value (count) is represented on the y-axis. You can control the field that is displayed in the histogram by setting the field in the Symbology tab of the Layer Properties dialog box.
HTML
Hypertext markup language. An HTML file contains text and tags instructing an Internet browser application how to present the text. For example, <B>24</B> will display the text "24" in bold.
hyperlink
Displays linked data, such as an image or Web page, when you click on it.

I
Identify
To click a feature with the identify tool, which opens a window showing that feature's attributes.
identity
The topological overlay of a coverage A (input) with a polygon coverage B (identity) that computes the geometric intersection of the two coverages. The output coverage preserves all the features of A plus those portions of B which overlap A. Features from coverage A are preserved in the output dataset and receive attributes from the polygons in B which they intersect. 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. See also intersect and union. See also intersect and union.
image
A raster-based representation or description of a scene, typically produced by an optical or electronic device. Common examples include remotely sensed data (for example, satellite data), scanned data, and photographs. An image is stored as a raster dataset of binary or integer values that represent the intensity of reflected light, heat, or other range of values on the electromagnetic spectrum. An image may contain one or more bands. See also raster and band.
indeterminate flow direction
For an edge feature, occurs when the flow direction cannot be determined from the topology of the network, the locations of sources and sinks, and the enabled or disabled states of features.
index
A special data structure used in a database to speed searching for records in tables or spatial features in geographic datasets. ArcInfo supports both spatial and attribute indexes.
INFO database
The contents of a set of INFO data files, feature attribute tables, and related files stored in an ArcInfo workspace under a subdirectory named INFO. This subdirectory contains all feature attribute tables for the coverages in the workspace.
Informix
A commercial RDBMS supported by ArcSDE.
instance
The name of the process running on the ArcSDE server that allows connections and access to spatial data. Also called Service.
integrated feature dataset
Topologically associated feature classes in a geodatabase are stored in an integrated feature dataset. You can use the topological editing tools in ArcMap to maintain the topological associations of features in an integrated feature dataset.
interpolate
To predict values for a surface from a limited number of sample data points.
interpolation
A set of Spatial Analyst functions that predict values for a surface from a limited number of sample data points, creating a continuous raster.
intersect
The topological integration of two spatial datasets that preserves features that fall within the area common to both input datasets. Compare with identity and union.
Inverse Distance Weighted (IDW)
An interpolation method in which cell values are estimated by averaging the values of sample data points in the vicinity of each cell. The closer a point is to the center of the cell being estimated, the more influence, or weight, it has in the averaging process.
IP address
The server's address on the network. The address consists of four numbers, each separated by a ".".
ISO
International Standards Organization. A worldwide federation of national standards bodies (for example, ANSI from the United States). ISO maintains many computing standards, including a SQL standard.
item
A column of information in an INFO table.
An element in the Catalog tree in ArcCatalog. The Catalog tree can contain both geographic data sources and nongeographic elements such as folders, folder connections, and file types.

J
job
A task scheduled on a Geoprocessing Server for immediate or future remote processing. A job can involve a single tool or a batch mode execution.
join
The process of attaching tabular data to geographic features. Attributes in an attribute table are appended to the features in a spatial data table using an attribute or item common to both tables. See also relational join.
junction element
A network feature that occurs at the intersection of two or more edges or at the endpoint of an edge that allows the transfer of flow between edges. See also logical network.