GIS Dictionary

A shortened form of a word or phrase which represents the whole. Abbreviations are commonly a letter or group of letters taken from the complete form of the word, such … Read more

[symbology] In Maplex for ArcGIS, a file that contains whole words and their abbreviated forms to allow automated shortening of labels.

[coordinate systems] In a rectangular coordinate system, the distance of the x-coordinate along a horizontal axis from the vertical or y-axis. For example, a point with the coordinates (7,3) has … Read more

Coordinates that are referenced to the origin of a given coordinate system.

[ESRI software] In Survey Analyst for field measurements, one of two possibilities for performing a constrained adjustment. In the absolutely constrained adjustment, the coordinates of the reference points keep their … Read more

[remote sensing] The amount of electromagnetic energy lost through interactions with gas molecules and matter during its passage through the atmosphere.

[cognition] A simplified idea of a real-world object or system.

[computing] A keyboard shortcut that allows a user to access the contents of the Main menu by holding down the Alt key and pressing the underlined letter on the menu … Read more

1 [business] An aggregate measure of the degree of ease with which a place, person, or thing can be reached, depending on factors such as slope, traffic, distance, and so … Read more

[mathematics] The degree to which a measured value conforms to true or accepted values. Accuracy is a measure of correctness. It is distinguished from precision, which measures exactness.

1 [ESRI software] Circles, lines, polygons, points, or markers that become transparent when not active. Acetate features are overlaid on other map layers and can be independently annotated. 2 [cartography] … Read more

[ESRI software] In ArcGIS, an XML file that contains an acknowledgement message.

[ESRI software] In ArcGIS, a message from a replica to its relative acknowledging the data changes received by the sending replica.

[programming] Acronym for access control list. A list of accounts or users used to designate restricted and unrestricted services and the authentication criteria required to access an object.

[remote sensing] A remote-sensing tool with an oscillating mirror that moves back and forth across a satellite’s direction of travel, creating scan line strips that are contiguous or that overlap … Read more

[ESRI software] The data frame currently being worked onfor example, the data frame to which layers are being added. The active data frame is highlighted on the map, and its … Read more

[ESRI software] In Survey Analyst for field measurements, the focus of the analyses applied. In an active network, users may list a network’s datum points in the Survey Explorer, detect … Read more

[remote sensing] A remote-sensing system, such as radar, that produces electromagnetic radiation and measures its reflection back from a surface.

[ESRI software] In ArcView 3.x, the theme in a view document to which button and tool actions or corresponding menu commands are applied. An active theme appears raised in a … Read more

[non-ESRI software] A type of ArcIMS Application Server Connector that is a Component Object Model (COM) dynamic link library (DLL) which can be used in a COM application such as … Read more

[photogrammetry] A measure, using a microdensitometer or other instrument, of how well a photographic system shows sharp edges between contiguous bright and dark areas.

[programming] An extension to a software program that performs a custom task. ESRI provides various developer add-ins as part of the ArcGIS developer kit.

[cadastral and land records] A designation of the location of a person’s residence or workplace, an organization, or a building, consisting of numerical and text elements such as a street … Read more

[geocoding] Data that contains address information used for geocoding. Address data may consist of one individual address or a table containing many addresses.

[geocoding] The arrangement of address information in a database, most often consisting of such address elements as house number, street direction, street name, street type, city, and postal code.

[geocoding] The rules of a geodatabase designed specifically to accommodate address-related material, such as streets, zones, ranges, and so forth. These rules define the address elements, their attribute values, and … Read more

[geocoding] One of the components that comprise an address. House numbers, street names, street types, and street directions are examples of address elements.

[address matching] In ArcGIS, features that can be located based on address matching with a street network or other address identifier, such as ZIP Codes or lot numbers.

[geocoding] In ArcGIS, a table containing addresses but no spatial reference information. Using GIS software, address event tables can be geocoded to create a spatial data layer.

[geocoding] A column in a table that stores one or some address elements. An address field can be present in reference data, address data, or both.

[geocoding] The particular structure and arrangement of address elements and a corresponding method of matching that can be used for a specific application. The address format may vary based on … Read more

[ESRI software] A dataset in ArcGIS that stores the address attributes, associated indexes, and rules that define the process for translating nonspatial descriptions of places, such as street addresses, into … Read more

[geocoding] A parameter in an address locator that defines the process of geocoding.

[geocoding] A template on which an address locator is built. Each template is designed to accommodate a specific format of address and reference data, and geocoding parameters. The address locator … Read more

[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 … Read more

[geocoding] 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. … Read more

[address matching] A service that can determine the x,y location of an address, and return the address of an x,y location.

[geocoding] The process of breaking down an address into elements and converting those elements with standard abbreviations or spellings. For best practices, this process applies to preparing the reference data … Read more

[geocoding] A tool that prepares and breaks down an address into elements that can be used for geocoding. The process may translate some elements into standard keywords or abbreviations; for … Read more

[database structures] The geodatabase system table, created when a feature class or table is registered as versioned, that maintains information on all rows that have been inserted or updated.

[Internet] Acronym for Application Developer Framework. The set of custom Web controls and templates that can be used to build Web applications that communicate with a GIS server. ArcGIS Server … Read more

[Internet] The components required to run an application built with the ADF.

[geography] A type of spatial relationship in which two or more polygons share a side or boundary.

[spatial analysis] A statement or logical expression used to select geographic features that share a boundary.

[ESRI software] In Survey Analyst for cadastres, a number that corresponds to a specific set of displacement vectors in a series of adjustments to the cadastral fabric. The adjustment level … Read more

The process of appropriating a technology and putting it into use for one’s own purposes; the act by an individual, organization, or community of choosing a technology and putting it … Read more

[programming] Acronym for abstract data type. For OpenLS, a data type and structure for location information that is shared by two or more services. ADTs are application schemas that are … Read more

[aerial photography] An aerial photograph from which distortions owing to camera tilt and ground relief have been removed. An orthophoto has the same scale throughout and can be used as … Read more

[defense] In MOLE, the type of threat posed by the war fighting element being represented. The four basic types supported by MOLE are unknown, friend, neutral, and hostile.

A geometric transformation that scales, rotates, skews, and/or translates images or coordinates between any two Euclidean spaces. It is commonly used in GIS to transform maps between coordinate systems. In … Read more

In modeling, an entity within a model that conducts transactions to simulate the actions of a human, group of humans, animal, or other actor.

A simulation of the large-scale consequences of the decisions and interactions of individual members of a population. An agent-based model consists of an environment or framework that defines the scope … Read more

[data editing] The process of collecting a set of similar, usually adjacent, polygons (with their associated attributes) to form a single, larger entity.

[programming] Acronym for Adobe Integrated Runtime. A cross-platform runtime environment built on HTML, Flash, and Flex. AIR applications are deployed on a desktop and can communicate with a server for … Read more

[navigation] Acronym for Aeronautical Information Exchange Format. An XML format used to describe aeronautical data transactions created and maintained by EUROCONTROL (European Organisation for the Safety of Air Navigation), in … Read more

[Internet] Acronym for Asynchronous JavaScript and XML. A programming technique for creating fast, interactive Internet applications. AJAX adds a small application to part of the software user’s browser for fast … Read more

[physics] A measure of the reflectivity of an object or surface; the ratio of the amount of radiation reflected by a body to the amount of energy striking it.

[usability] A message that calls attention to a notable situation or informs users of changes in the state of a monitored situation.

1 [computing] An alternative name specified for fields, tables, files, or datasets that is more descriptive and user-friendly than the actual name. On computer networks, a single e-mail alias may … Read more

[graphics computing] The jagged appearance of curves and diagonal lines in a raster image. Aliasing becomes more apparent as the size of the raster pixels is increased or the resolution … Read more

1 [surveying] A peep sight mounted on a straightedge and used to measure direction. 2 [surveying] The part of a theodolite containing the telescope and attachments.

[ESRI software] A task that identifies the fields required for geocoding, such as address and city, when uploading data.

A drafting symbol that runs parallel to the baseline and indicates the true distance between beginning and ending dimension points.

[network analysis] In network analysis, the process of assigning entities or edges and junctions to features until the feature’s capacity or limit of impedance is reached. For example, streets may … Read more

1 [GPS] In GPS, a file transmitted from a satellite to a receiver that contains information about the orbits of all satellites included in the satellite network. Receivers refer to … Read more

[remote sensing] A remote-sensing tool with a line of many fixed sensors that record reflected radiation from the terrain along a satellite’s direction of movement, creating scan-line strips that are … Read more

[cartography] A grid of numbered rows and lettered columns (or vice versa) superimposed on a map, used to find and identify features. Alphanumeric grids are commonly used as a reference … Read more

[database structures] An attribute or set of attributes in a relational database that provides a unique identifier for each record and could be used as an alternative to the primary … Read more

[geocoding] A name for an address element, usually a street name, that is different from the official or most common name. For example, a highway number might be an alternate … Read more

1 [coordinate systems] The height or vertical elevation of a point above a reference surface. Altitude measurements are usually based on a given reference datum, such as mean sea level. … Read more

Acronym for automated mapping/facilities management. GIS or CAD-based systems used by utilities and public works organizations for storing, manipulating, and mapping facility information such as the location of geographically dispersed … Read more

[uncertainty] In GIS, a state of uncertainty in data classification that exists when an object may appropriately be assigned two or more values for a given attribute. For example, coastal … Read more

[ESRI software] Acronym for ARC Macro Language. A proprietary, high-level programming language created by ESRI for generating end-user applications in ArcInfo Workstation.

[map display] A stereo image made by superimposing two images of the same area. The images are displayed in complementary colors, usually red and blue or green. When viewed through … Read more

[graphics computing] An image represented by continuous variation in tone, such as a photograph.

[analysisgeoprocessing] A systematic examination of a problem or complex entity in order to provide new information from what is already known.

[spatial analysis] The geographic bounding area within which spatial analysis will occur. The bounding area is set by defining the x,y coordinates of opposite corners, usually the bottom-left and top-right … Read more

[statistics] A statistical procedure used to evaluate the variance of the mean values for two or more datasets in order to assess the probability that the data comes from the … Read more

[digital image processing] In digital image processing, data from sources other than remote sensing, used to assist in analysis and classification or to populate metadata.

[database structures] A supplementary source of information.

[geodesy] The unit of measurement on a sphere or a spheroid, usually degrees. Some map projection parameters, such as the central meridian and standard parallel, are defined in angular units.

[3D analysis] In ArcMap, ArcScene, and ArcGlobe, a collection of animation tracks that define the dynamic property changes to associated objects. An animation allows for navigation through the display, visualization … Read more

[3D analysis] In ArcMap, ArcScene, and ArcGlobe, the interface in which the keyframes, tracks and time-scale properties of an animation can be edited and an animation can be timed and … Read more

[modeling] Having nonuniform spatial distribution of movement or properties, usually across a surface.

[map design] In cartography, text or graphics on a map that provide information for the map reader. Annotation may identify or describe a specific map entity, provide general information about … Read more

[map design] A subset of annotation in a standard or feature-linked geodatabase annotation feature class that contains properties that determine how the subset of annotation will display. A standard or … Read more

[map design] One of a number of procedures that dictate what type of annotation feature is created and the number of points required to create new annotation features. Construction methods … Read more

[map design] A geodatabase feature class that stores text or graphics that provide information about features or general areas of a map (annotation). An annotation feature class may be linked … Read more

[map design] A container within a map document for organizing and managing text or graphics that provide additional information about features or general areas of a map. Annotation groups allow … Read more

[map design] A layer that references annotation. Information stored for annotation includes a text string, a position at which it can be displayed, and display characteristics.

[map design] In ArcMap, the annotation group or feature class in a map document where new annotation will be stored when created when using the New Text tools on the … Read more

Acronym for American National Standards Institute. The private, nonprofit organization that develops U.S. industry standards through consensus and public review.

[programming] An open-source, Java-based tool from the Apache Software Foundation that is used to manage the build procedure of applications.

[geodesy] Any point on the surface of a sphere that lies 180 degrees (opposite) from a given point on the same surface, so that a line drawn between the two … Read more

[network analysis] In network datasets, a type of edge connectivity policy that states that an edge may connect to another edge or junction where they have coincident vertices.

[GPS] A position that a GPS receiver can calculate without knowing its own location or the local time.

[programming] In Microsoft’s COM component programming model, a group of threads, working within a process, that work within the same context.

[programming] Acronym for application programming interface. A set of interfaces, methods, protocols, and tools that application developers use to build or customize a software program. APIs make it easier to … Read more

In an orbit path, the point at which the object in orbit is farthest from the center of the body being orbited.