GIS Dictionary

[GPS] The group of radio frequencies that carry data from GPS satellites to GPS receivers.

1 [cartography] In cartography, text placed on or near a map feature that describes or identifies it. 2 [ESRI software] In ArcGIS, descriptive text, usually based on one or more … Read more

[ESRI software] In ArcMap, a category of labels that represents features with the same labeling properties. For example, in a roads layer, label classes could be created to define information … Read more

[ESRI software] A statement that determines the label text. Label expressions typically concatenate or modify the contents of one or more fields, and may add additional text strings to create … Read more

[ESRI software] In Maplex for ArcGIS, a tab on the Label Placement dialog box that allows control of the ways the label engine can fit more labels into a limited … Read more

[ESRI software] In ArcMap, the tool used to display and set labeling properties for the currently active data frame. The Label Manager is accessible through the Labeling toolbar.

[ESRI software] The distance a label should be from the feature it labels. A label offset and a maximum label offset can be set for point features. Maximum label offsets … Read more

[ESRI software] The maximum distance away from a point feature that a label may be placed, beyond the specified offset.

[ESRI software] The angle or direction of alignment for feature labels. Labels for features are usually placed horizontally, but they may also be oriented to an angle stored as an … Read more

[ESRI software] A parameter used to define a placement property for a label. Label placement properties include such properties as label offset, label placement zone, label fitting strategy, label prioritiy, … Read more

[ESRI software] One of eight designated areas on a map, radiating from a point, in which labels may be placed. The user can indicate in which of eight zones labels … Read more

[ESRI software] In a coverage, a feature class used to represent points or identify polygons. When representing points, the x,y location of the point describes the location of the feature. … Read more

[ESRI software] In Maplex for ArcGIS, a tab on the Label Placement dialog box that allows control of how labels are placed relative to features. The position of a label … Read more

[ESRI software] In ArcGIS, a ranking system that determines the order in which labels will be placed on a map. Labels with higher priority will be placed before labels with … Read more

[ESRI software] The splitting of long labels to place the text on two or more lines. Maplex for ArcGIS allows specification of which characters trigger a split and whether or … Read more

[ESRI software] An ESRI Standard Label Engine ranking system that indicates whether labels from a given label class may be covered by another label in cases in which label placement … Read more

[ESRI software] In the creation of a semivariogram, the sample distance used to group or bin pairs of points. Using an appropriate lag distance can be helpful in revealing scale-dependent … Read more

[computing] Acronym for local area network. Communications hardware and software that connect computers in a small area, such as a room or a building. Computers in a LAN can share … Read more

[geography] The classification of land according to the vegetation or material that covers most of its surface; for example, pine forest, grassland, ice, water, or sand.

[government] A geographic information system for cadastral and land-use mapping, typically used by local governments.

[geography] The classification of land according to what activities take place on it or how humans occupy it; for example, agricultural, industrial, residential, urban, rural, or commercial.

[geography] Any natural feature of the land having a characteristic shape, including major forms such as plains and mountains and minor forms such as hills and valleys.

1 [geography] Any prominent natural or artificial object in a landscape used to determine distance, bearing, or location. 2 [geography] A building or location that has historical, architectural, or cultural … Read more

[satellite imaging] Multispectral, earth-orbiting satellites developed by NASA (National Aeronautics and Space Administration) that gather imagery for land-use inventory, geological and mineralogical exploration, crop and forestry assessment, and cartography.

[environmental GIS] The study of spatial patterns, processes, and change across biological and cultural structures within areas encompassing multiple ecosystems.

[cartography] Generally, a map scale that shows a small area on the ground at a high level of detail.

[printing] A printing device capable of producing an image on large paper or other media sized between 36 and 87 inches (91 and 220 centimeters) wide. Modern large format printers … Read more

[3D GIS] An industry-standard binary file format that maintains information related to lidar data.

[database structures] A geodataset that references LAS files and surface constraints, and enables a person to examine LAS files in their native format.

[programming] A COM technique that an application uses for determining an object’s properties and methods at run time, rather than when the code is compiled. Late binding is generally used … Read more

The angular distance, usually measured in degrees north or south of the equator. Lines of latitude are also referred to as parallels.

The latitude value that defines the center, and sometimes the origin, of a projection.

The latitude value that defines the origin of the y-coordinate values for a projection.

[coordinate systems] A reference system used to locate positions on the earth’s surface. Distances eastwest are measured with lines of longitude (also called meridians), which run northsouth and converge at … Read more

A representation of a surface using an array of regularly spaced sample points (mesh points) that are referenced to a common origin and have a constant sampling distance in the … Read more

1 [data structures] The visual representation of a geographic dataset in any digital map environment. Conceptually, a layer is a slice or stratum of the geographic reality in a particular … Read more

[data structures] In ArcGIS, a file with a .lyr extension that stores the path to a source dataset and other layer properties, including symbology.

[Internet] A special file (layer_name.lpk) that contains a layer, a copy of the data, and an XML file that has a brief description of the layer. It can be opened … Read more

1 [map design] The arrangement of elements on a map, possibly including a title, legend, north arrow, scale bar, and geographic data. 2 [ESRI software] In ArcGIS, a presentation document … Read more

[ESRI software] In ArcMap and ArcReader, a view that shows the virtual page upon which geographic data and map elements, such as titles, legends, and scale bars, are placed and … Read more

[ESRI software] In MOLE, typically two or more force elements grouped together and placed on a line based on user-specified rules. Leaders are often used to clean up the map … Read more

[network analysis] The path between two locations that costs the least to traverse, where cost is a function of time, distance, or some other criteria defined by the user.

[surveying] A statistical method for providing a best fit for survey point locations and detecting measurement error by minimizing the sum of the squares of measurement residuals. The method allows … Read more

[surveying] The final measurement residuals of a least squares adjustment.

[ESRI software] The topological data structure in an ArcInfo coverage that stores, for each arc, the identity of the polygons to the left and right of it. Left-right topology supports … Read more

[ESRI software] The geometric shape of either a line or a polygon that is used to represent a specific kind of feature in a legend and in the ArcMap table … Read more

[ESRI software] An abstraction of a layer in ArcGlobe portraying the layer at some degree of resolution between simplified and unsimplified.

In surveying, the measurement of the heights of objects and points according to a specified elevation, usually mean sea level.

[ESRI software] Acronym for Library Identifier. A type of GUID consisting of a unique string assigned to a type library.

1 [programming] In object-oriented programming, a logical grouping of classes, usually with a header section that lists the classes in the library. 2 [ESRI software] In ArcInfo, a collection of … Read more

[intellectual property rights] The grant to a party of the right to use a software package or component. A license differs from a sale in that the user does not … Read more

[ESRI software] A file that contains License Manager license data. Each license file contains information such as the SERVER, ESRI_SENTINEL_KEY number (Windows only), Version, the number of seats, and so … Read more

[remote sensing] Acronym for light detection and ranging. A remote-sensing technique that uses lasers to measure distances to reflective surfaces.

[ESRI software] In ArcScene and ArcGlobe, vectors normal to a geometry’s surface, stored in that geometry to help define how lighting affects it.

[ESRI software] In Survey Analyst for field measurements, restrictions that define an acceptable level of measurement error for each computation.

[Euclidean geometry] On a map, a shape defined by a connected series of unique x,y coordinate pairs. A line may be straight or curved.

[ESRI software] A procedure that combines groups of individual lines with the same name into a single line for the label engine. This is often necessary because lines such as … Read more

[linear referencing] In linear referencing, a description of a portion of a route using a from- and to-measure value. Examples of line events include pavement quality, salmon spawning grounds, bus … Read more

[symbology] A map feature that has length but not area at a given scale, such as a river on a world map or a street on a city map.

1 [3D analysis] A line drawn between two points, an origin and a target, that is compared against a surface to show whether the target is visible from the origin … Read more

[cartography] A generalization technique in which vertices are selectively removed from a line feature to eliminate detail while preserving the line’s basic shape.

The process of adding extra points to lines to reduce the sharpness of angles between line segments, resulting in a smoother appearance.

[linear referencing] In linear referencing, the overlay of two line event tables to produce a single line event table. The new event table can be the logical intersection or union … Read more

[linear referencing] In linear referencing, the overlay of a line event table and a point event table to produce a single point event table. The new event table can be … Read more

[ESRI software] A collection of states representing the changes that have occurred over time in a versioned geodatabase.

A measurement of the horizontal or vertical dimension of a feature. Linear dimensions may not represent the true distance between beginning and ending dimension points because they do not take … Read more

[spatial statistics use for geostatistics] The estimation of an unknown value using the linear distance between known values.

[linear referencing] A method for storing geographic data by using a relative position along an already existing line feature; the ability to uniquely identify positions along lines without explicit x,y … Read more

[cartography] The unit of measurement on a plane or a projected coordinate system, often meters or feet.

1 [photogrammetry] In georeferencing, connections added between known points in a dataset being georeferenced and corresponding points in the dataset being used as a reference. 2 [computing] An operation that … Read more

[ESRI software] In Survey Analyst for field measurements, a command that finds nearby survey points for each feature vertex and automatically creates links. The command allows the user to specify … Read more

[ESRI software] In Survey Analyst for field measurements, lines displayed on a map after a survey point and a feature vertex are linked.

[ESRI software] In Survey Analyst for field measurements, a tool that allows the user to make a link between a survey point and a feature vertex by snapping and clicking … Read more

[ESRI software] In Survey Analyst for field measurements, one of two types of pages in the Survey Explorer. The List page lists multiple survey objects.

[hardware] A computer hardware architecture in which, within a multibyte numeric representation, the least significant byte has the lowest address and the remaining bytes are encoded in increasing order of … Read more

[software] The act of distributing application, network, and/or server resources to optimize performance.

[data editing] The computation of an output raster where the output value at each location is a function of the input value at the same location.

[ESRI software] In Survey Analyst for field measurements, one of two ways to apply the Coordinate Out of Tolerance command. The Local check method searches for coordinates out of tolerance … Read more

1 [geodesy] A horizontal geodetic datum that serves as a basis for measurements over a limited area of the earth; that has its origin at a location on the earth’s … Read more

[spatial statistics use for geostatistics] In ArcGIS Geostatistical Analyst, a deterministic interpolation method. The interpolated surface is not required to conform to the sample data points, and the method does … Read more

[organizational issues] The process of adapting software to the requirements of a different language or culture, including translating user interfaces, documentation, and help systems; customizing features; and accommodating different character … Read more

1 [geography] An identifier assigned to a region or feature. 2 [geography] A position defined by a coordinate value.

[non-ESRI software] Services that allow IBM WebSphere Everywhere Access (WEA) application providers to use location-based services from multiple vendors, by providing an application programming interface (API).

The process of finding the best locations for one or more facilities that will service a given set of points and then assigning those points to the facilities, taking into … Read more

[location-based services] Information or a physical service delivered to multiple channels, exclusively based on the determined location of a wireless device. Some location-based applications include emergency services, information services, and … Read more

[ESRI software] In Survey Analyst – Cadastral Editor, a parcel that has been locked for editing. Locked parcels cannot be edited simultaneously in a multiuser environment.

[wayfinding] The movements of a person following a route. Locomotion is the physical component of navigation.

[computing] A database file that records changes in data, often used as part of a database restoration.

[mathematics] The power to which a fixed number (the base) must be raised to equal a given number. The three most frequently used bases for logarithms are base 10, base … Read more

[mathematics] A string of numbers, constants, variables, operators, and functions that returns a value of true or false.

[ESRI software] An abstract representation of a network, implemented as a collection of hidden tables. A logical network contains edge, junction, and turn elements, the connectivity between them, and the … Read more

[mathematics] An operator used to compare logical expressions that returns a result of true or false. Examples of logical operators include less than (), equal to (=), and not equal … Read more

[analysisgeoprocessing] The process of using mathematical expressions to select features from a geographic layer based on their attributes; for example, “select all polygons with an area greater than 16,000 units” … Read more

[ESRI software] An edit session on a feature dataset that may last from a few minutes to several months. Long transactions are managed by the ArcSDE versioning mechanism.

[spatial statistics use for geostatistics] In a spatial model, coarse-scale variation that is usually modeled as the trend.

The angular distance, usually expressed in degrees, minutes, and seconds, of the location of a point on the earth’s surface east or west of an arbitrarily defined meridian (usually the … Read more

The longitude value that defines the center, and sometimes the origin, of a projection.

The longitude value that defines the origin of the x-coordinate values for a projection.

A relatively unstructured relationship between two software components or programs that work together to process data, which requires little overlap between methods, ontologies, class definitions, and so on.

[ESRI software] A replication model that does not require the parent and child replicas to be directly connected for synchronization to occur. Loosely coupled replication is an asynchronous model, so … Read more