GIS Dictionary

[programming] A COM technique an application uses to access an object. In early binding, an object’s properties and methods are discovered from an interface at compile time, instead of being … Read more

1 [coordinate systems] The distance east of the origin that a point in a Cartesian coordinate system lies, measured in that system’s units. 2 [coordinate systems] The positive x-value in … Read more

[Euclidean geometry] A measure of how much an ellipse deviates from a circle, expressed as the ratio of the distance between the center and one focus of an ellipsoid to … Read more

1 [astronomy] The great circle formed by the intersection of the plane of the earth’s orbit around the sun (or apparent orbit of the sun around the earth) and the … Read more

[statistics] The assumption that an individual from a specific group or area will exhibit a trait that is predominant in the group as a whole.

[geography] The field of geography concerning the distribution and variation of economic factors by location, including how economic factors interact with geographic factors such as climate, land use, and geology.

1 [data models] A line between two points that forms a boundary. In a geometric shape, an edge forms the boundary between two faces. In an image, edges separate areas … Read more

[network analysis] In network datasets, a connectivity policy that defines how one edge may connect to another edge mid-span. There are two edge-edge connectivity policies: endpoint connectivity and any-vertex connectivity.

A digital image processing technique for isolating edges in a digital image by examining it for abrupt changes in pixel value.

A digital image processing technique for emphasizing the appearance of edges and lines in an image.

[network analysis] In geometric networks, a connectivity rule that defines how one edge may connect to another edge through a junction.

[ESRI software] In connectivity relationships for networks, the number of edges of one type that may be associated with junctions of another type. Edge-junction cardinality defines a range of permissible … Read more

[ESRI software] In geometric networks, a connectivity rule that defines how an edge may connect to a junction.

[data editing] A spatial adjustment process that aligns features along the edge of an extent to the corresponding features in an adjacent extent.

[ESRI software] A tool on the Annotation toolbar that is used to manipulate geodatabase annotation. Text can be interactively moved, scaled, and rotated. Shortcut menu options allow control of the … Read more

[data editing] The portion of a coverage where the geometry (or geographical features) has been altered, but where topology has not yet been restored.

[ESRI software] In ArcGIS, the environment in which spatial and attribute editing take place. After starting an edit session, a user can modify feature locations, geometry, or attributes. Modifications made … Read more

[ESRI software] In ArcGIS, a temporary, underlying representation that is used to create or edit feature geometry.

[ESRI software] During editing prior to ArcGIS 10, a setting in the Task drop-down list that determines which operation the sketch construction tools will perform. Examples of edit tasks include … Read more

[ESRI software] In ArcMap, a set of tools that allows the creation and modification of features and their attributes.

[non-ESRI software] Acronym for electronic document management system. A computer-based system for organizing, maintaining, and retrieving digital and hard-copy documents. An EDMS usually includes a check-in, check-out system for document … Read more

[ESRI software] Acronym for ESRI Developer Network. A subscription program used to acquire ESRI software for developers, which includes a special program for supporting the ESRI developer community. EDN is … Read more

[physics] Energy that moves through space at the speed of light as different wavelengths of time-varying electric and magnetic fields. Types of electromagnetic radiation include gamma, x, ultraviolet, visible, infrared, … Read more

[physics] The entire range of wavelengths (frequencies) over which electromagnetic radiation extends.

[map display] A mapping system that displays but does not allow for the spatial analysis of data.

[ESRI software] In geoprocessing in ArcGIS, a component of a model. Elements can be variables, such as input and derived data, or tools.

[geodesy] The vertical distance of a point or object above or below a reference surface or datum (generally mean sea level). Elevation generally refers to the vertical height of land.

[symbology] A map element that displays a simplified representation of the terrain within a map’s extent. Elevation guides are designed to provide a quick overview of topography, including the high … Read more

[ESRI software] A layer in ArcGlobe that has been categorized to help define the geometry of the globe surface.

[symbology] Hypsometric tint bands based on elevation ranges used in an elevation guide.

A geometric shape described mathematically as the collection of points whose distances from two given points (the foci) add up to the same sum. An ellipse is shaped like a … Read more

1 [Euclidean geometry] A three-dimensional, closed geometric shape, all planar sections of which are ellipses or circles. An ellipsoid has three independent axes, and is usually specified by the lengths … Read more

[3D GIS] A multipoint feature class embedded into a terrain dataset. When a feature class is embedded, it is incorporated directly into the terrain pyramid and the terrain becomes the … Read more

[non-ESRI software] Acronym for Enhanced Metafile. A spool file format used in printing by the Windows operating system.

[statistics] That property of a quantity that indicates that the quantity depends on data, observations, or experiment only; that is, it is not a model or part of a model. … Read more

[ESRI software] In geometric networks, a network feature that allows flow to pass through it.

[navigation] Acronym for electronic navigational chart. A vector data product used for nautical navigation. ENC data is produced by nautical charting agencies throughout the world and uses the IHO (International … Read more

[data transfer] A file describing the contents of an item included in metadata. Enclosing files in metadata works the same way as enclosing files in an e-mail message.

[data conversion] The recording or reformatting of data into a computer format. Data may be encoded to reduce storage, increase security, or to transfer it between systems using different file … Read more

[ESRI software] In linear referencing, a special type of hatch definition that draws hatch marks only at the low and high measure of a linear feature.

[ESRI software] An adjustable value that dictates how far away from the end of a line an address location should be placed. Using an end offset prevents the point from … Read more

[network analysis] In network datasets, a type of edge connectivity policy that states that an edge may only connect to another edge at its endpoints.

[remote sensing] In remote sensing, applying operations to raster data to improve appearance or usability by making specific features more detectable. Such operations can include contrast stretching, edge enhancement, filtering, … Read more

[organizational issues] A geographic information system that is integrated through an entire organization so that a large number of users can manage, share, and use spatial data and related information … Read more

[non-ESRI software] The server-side component architecture for the J2EE platform. EJB enables development of distributed, transactional, secure, and portable Java applications.

The rectangle surrounding one or more geographical features in coordinate space, determined by the minimum and maximum coordinates in the x and y directions, as well as the ranges of … Read more

[ESRI software] Settings that can apply to all tools within the application, all tools within a model or script, or a particular process within a model or script. Environment settings … Read more

[computing] A variable maintained by the operating system and shared among programs. Environment variables function as placeholders for environment information, such as a drive, path or file name.

An abstract representation of a complex environmental process, emphasizing relationships and patterns in natural systems. Environmental models allow decision makers to better understand the effects of natural systems or the … Read more

[ESRI software] An ArcGIS utility application that can be used to investigate the contents of object libraries.

A table of the predicted positions of a satellite within its orbit for each day of the year, or for other regular intervals.

[coordinate systems] A coordinate system identification created by the European Petroleum Survey Group.

[business] A trade area boundary set halfway between a store or service point and its neighboring stores or service points.

[cartography] A data classification method that divides polygon features into groups so that the total area of the polygons in each group is approximately the same.

A projection in which the whole of the map as well as each part has the same proportional area as the corresponding part of the earth. An equal-area projection may … Read more

[ESRI software] In ArcInfo, a command that removes or deletes features from one coverage that overlap features in another coverage.

environmental GIS

1 [data quality] A measured, observed, calculated, or interpreted value that differs from the true value or the value that would be obtained by a perfect observer using perfect equipment … Read more

1 [uncertainty] In GIS data processing, the persistence of an error into new datasets calculated or created using datasets that originally contained errors. The study of error propagation is concerned … Read more

[ESRI software] A geodatabase table used by the GIS Data ReViewer to track error information through the quality control process. Defects are recorded, resolved and verified in the error table.

[ESRI software] An ESRI data format for storing raster data that defines geographic space as an array of equally sized square cells arranged in rows and columns. Each cell stores … Read more

[ESRI software] In Maplex for ArcGIS, extended software that allows finer control of how labels are placed.

[ESRI software] In ArcMap, the software used to place labels.

[ESRI software] A binary serialized file created in the ArcIMS 3.x AppServer directory to save site parameters. This file has now been replaced by ArcIMSSite.sez.

[ESRI software] A binary serialized file created in the ArcIMS 3.x AppServer directory to store ArcIMS Folders and any submitted MapNotes and EditNotes. This file has now been replaced by … Read more

[spatial statistics use for geostatistics] In spatial modeling, the process of forming a statistic from observed data to assign optimal parameters in a model or distribution.

The straight-line distance between two points on a plane. Euclidean distance, or distance “as the crow flies,” can be calculated using the Pythagorean theorem.

[ESRI software] In ArcGIS Spatial Analyst, a description of each raster cell’s relationship to the closest source.

[network analysis] A function that determines attribute values for network elements in a network dataset. If a network source does not have an evaluator, the default evaluator for its element … Read more

[linear referencing] A geographic location stored in tabular rather than spatial form. Event types include address events, route events, x,y events, and temporal events.

[programming] Watching for events that are broadcast by another class, and taking action when they occur.

[ESRI software] In ArcGIS, a layer created from an event table.

[linear referencing] In linear referencing, an operation that produces a route event table that is the logical intersection or union of two input route event tables. Event overlay is one … Read more

[linear referencing] A data source containing location information in tabular format (called events) that is used to create a spatial dataset. For example, an event table might contain x,y coordinates … Read more

[ESRI software] In ArcView 3.x, a spatial data theme created from an event table.

[ESRI software] An error that is an acceptable violation of a topology rule. In ArcMap, for example, a cul-de-sac is a legitimate exception to the rule that prohibits dangles.

A binary file containing a program that can be run as a stand-alone application. In the Microsoft Windows program, executable files are designated with an .exe extension.

[ESRI software] 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.”

[ESRI software] An editing process that separates a multipart feature into its component features, which become independent features.

[mathematics] In mathematics, a number that indicates how many times a base value is multiplied by itself. Exponents are usually indicated with superscripts.

[computing] To move data from one computer system to another, and often, in the process, from one file format to another.

[computing] To move data from one computer system to another, and often, in the process, from one file format to another.

[aerial photography] In aerial photography, each point in the flight path at which the camera exposes the film.

A sequence of operands and operators constructed according to the syntactic rules of a symbolic language that evaluates to a single number, string, or value.

[programming] In AutoCAD, extra optional data attached to an AutoCAD drawing element.

[ESRI software] In ArcGIS, an optional software module that adds specialized tools and functionality to ArcGIS Desktop. ArcGIS Network Analyst, ArcGIS StreetMap, and ArcGIS Business Analyst are examples of ArcGIS … Read more

The minimum bounding rectangle (xmin, ymin and xmax, ymax) defined by coordinate pairs of a data source. All coordinates for the data source fall within this boundary.

[ESRI software] A rectangle that is displayed in one data frame, showing the size and position of another data frame.

[ESRI software] A private ArcIMS virtual server that clips data and saves it to a Zip file.

[ESRI software] An ArcToolbox wizard that selects features from a coverage based on attribute values to create a new coverage.

[data management] A specification that defines parameters for feature extraction and attribution. Specifications typically include the size of features to be collected, density of feature collection, scale ranges, and attribute … Read more

[statistics] Using known or observed data to infer or calculate values for unobserved times, locations or other variables outside a sampled area. In the absence of data, extrapolation is a … Read more

[3D analysis] The process of projecting features in a two-dimensional data source into a three-dimensional representation: points become vertical lines, lines become planes, and polygons become three-dimensional blocks. Uses of … Read more