GIS Dictionary

1 [linear referencing] In linear referencing, a measure value that is added to a line feature. M-values are used to measure the distance along a line feature from a vertex … Read more

[programming] A computer program, usually a text file, containing a sequence of commands that are executed as a single command. Macros are used to perform commonly used sequences of commands … Read more

[navigation] A bearing measured relative to magnetic north.

[geodesy] The angle between magnetic north and true north observed from a point on the earth. Magnetic declination varies from place to place, and changes over time, in response to … Read more

[geography] The direction from a point on the earth’s surface following a great circle toward the magnetic north pole, indicated by the north-seeking end of a compass.

[physics] An instrument used to measure variations in the strength and direction of the earth’s magnetic field.

[ESRI software] A secondary window in ArcMap data view that shows a magnified view of a small area without changing the map extent. Moving the Magnifier window around will not … Read more

[ESRI software] A license that has a current maintenance contract with ESRI Customer Service. ESRI software users who have maintenance licenses are eligible for upgrade to the latest version of … Read more

[computing] The date a maintenance contract expires for a particular product. Multiple copies of the same product may expire on different dates.

The longer axis of an ellipse or spheroid.

[spatial statistics use for geostatistics] A technique for resampling raster data in which the value of each cell in an output is calculated, most commonly using a 2×2 neighborhood of … Read more

[ESRI software] In ArcGIS Spatial Analyst, an option that creates a permanent raster (one that is saved to disk) from a temporary result.

[data structures] A raster catalog in which the raster datasets are copied to a location assigned by a geodatabase. When a row is deleted from a managed raster catalog, the … Read more

[database structures] An association between two linked or joined tables in which one record in the first table may correspond to many records in the second table, and vice versa.

[database structures] An association between two linked or joined tables in which many records in the first table may correspond to a single record in the second table.

1 [cartography] A graphic representation of the spatial relationships of entities within an area. 2 [cartography] Any graphical representation of geographic or spatial information. 3 [ESRI software] The document used … Read more

[data analysis] A language that defines a syntax for combining map themes by applying mathematical operations and analytical functions to create new map themes. In a map algebra expression, the … Read more

[ESRI software] In ArcGIS, text or graphics stored within the map data frame in an annotation group. Map annotation may be manually entered or generated from labels, and can be … Read more

[ESRI software] A setting used in ArcMap that allows temporary storage of geodatabase or ArcIMS feature service features from a given map extent in the desktop computer’s RAM, which may … Read more

In ArcIMS, the file that contains the core site information. ArcIMS configuration files contain all the basic information about the content to be delivered, such as location of the data … Read more

[graphics map display] A graphic representation of a map on a computer screen.

[cartography] In ArcMap, the file that contains one map, its layout, and its associated layers, tables, charts, and reports. Map documents can be printed or embedded in other documents. Map … Read more

[map design] In digital cartography, a distinctly identifiable graphic or object in the map or page layout. For example, a map element can be a title, scale bar, legend, or … Read more

[cartography] The limit of the geographic area shown on a map, usually defined by a rectangle. In a dynamic map display, the map extent can be changed by zooming and … Read more

[cartography] Decreasing the level of detail on a map so that it remains uncluttered when its scale is reduced.

[ESRI software] In ArcInfo Workstation Map Librarian, a collection of geographic data partitioned spatially as a set of tiles and thematically as a set of layers, indexed by location for … Read more

The activity of viewing a map in a way that allows the viewer to make sense of or gain information from it. Map reading involves interpreting the meanings of codes … Read more

A collection of maps usually addressing a particular theme.

[Internet] A type of Web service that generates maps.

[cartography] A single map or chart in a map series, such as any one of the approximately 57,000 USGS 7.5-minute topographic maps of the United States and its territories.

[map design] Any of the supporting objects or elements that help a reader interpret a map. Typical map surround elements include the title, legend, north arrow, scale bar, border, source … Read more

[ESRI software] In ArcMap, a kind of map document that provides a quick way to create a new map. Templates can contain data, a custom interface, and a predefined layout … Read more

[graphics map display] A temporary set of topological relationships between coincident parts of simple features on a map, used to edit shared parts of multiple features.

The ground unit of measurementfor example, feet, miles, meters, or kilometersin which coordinates of spatial data are stored.

[ESRI software] An ArcGIS Server software component that provides programmatic access to the contents of a map document on disk and creates images of the map contents based on user … Read more

[ESRI software] In ArcGIS, a user-assistance component that displays an on-screen description of a map feature when the mouse is paused over that feature.

A symbol used to represent a point location on a map.

A geographic zone containing the people who are likely to purchase a firm’s goods or services.

A process that determines the percentage of a market area being reached based on the number of customers within an area divided by the total population in that area.

[programming] The process that enables communication between a client object and server object in different apartments of the same process, between different processes, or between different processes on different machines … Read more

[ESRI software] In Internet mapping, the combination of content from more than one data source into one dynamic map service.

1 [cartography] In digital cartography, a means of covering or hiding features on a map to enhance cartographic representation. For example, masking is often used to cover features behind text … Read more

An irregularly distributed sample point, with an x-, y-, and z-value, used to build a triangulated irregular network (TIN). Ideally, mass points are chosen to capture the more important variations … Read more

[database structures] In ArcGIS 9.1 and previous versions, the data version in the master geodatabase, created when data is checked out, that represents the state of the data at the … Read more

[database structures] In ArcGIS 9.1 and previous versions, a geodatabase from which data has been checked out.

[ESRI software] In Business Analyst, the site of a known, well-performing business.

[geocoding] In geocoding, a value assigned to all potential candidates for an address match. The match score is based on how well the location found in the reference data matches … Read more

[geocoding] In geocoding, the process of linking a record, such as an address, to a set of reference data. The matched record in the reference data is used to determine … Read more

A kind of expression that evaluates to a number which is then typically stored in a variable, a field on a table row, or a cell in a raster dataset. … Read more

[ESRI software] In ArcGIS Spatial Analyst, a function that applies a mathematical operation to the values of a single input raster. There are four groups of mathematical functions available: logarithmic, … Read more

[ESRI software] In Survey Analyst for field measurements, a set of relations between measurements and unknown coordinates.

[mathematics] A rectangular arrangement of data, usually numbers, in rows and columns. In computer science, a two-dimensional array is called a matrix. In GIS, matrices are used to store raster … Read more

[spatial analysis] Acronym for modifiable areal unit problem. A challenge that occurs during the spatial analysis of aggregated data in which the results differ when the same analysis is applied … Read more

[map display] The maximum bounding rectangle (in x,y coordinates) of an on-screen map. Users cannot zoom out beyond the max extent.

[mathematics] The average for a set of values, computed as the sum of all values divided by the number of values in the set.

[spatial statistics use for geostatistics] The location of a single x,y coordinate value that represents the average x-coordinate value and the average y-coordinate value of all features in a study … Read more

[geodesy] The average height of the surface of the sea for all stages of the tide over a nineteen-year period, usually determined by averaging hourly height readings from a fixed … Read more

[spatial statistics use for geostatistics] In geostatistics, a property of a spatial process in which a spatial random variable has the same mean value at all locations.

[linear referencing] In linear referencing, either one or two fields in a table that describe the position of an event along a route.

[standards] An observed numerical value that is an appraisal of size, extent, or amount according to a set criteria.

[surveying] In surveying, the noise that is expected in every measurement. It occurs because the observer makes estimates and uses measuring equipment that is unpredictable in an environment that is … Read more

[surveying] The difference between a measured quantity and its theoretical true value as determined during each iteration of a least-squares adjustment.

1 [mathematics] The middle value of a set of values when they are ordered by rank. Half the values in a set are higher than the median, and half are … Read more

[spatial statistics use for geostatistics] A location representing the shortest total distance to all other features in a study area.

[printing] A printing device capable of producing an image on paper or other media sized between 15 and 35 inches (38 and 90 centimeters) wide. Medium-format printers typically use inkjet … Read more

1 [programming] Refers collectively to the properties and methods, or functions, of an interface or class. 2 [Internet] In ArcGIS Online, ArcGIS users who have registered for ArcGIS Online. Members … Read more

[computing] In ArcGlobe, the amount of system memory that the application will use.

[computing] In computer programming, the loss of computer memory that occurs when an application or component fails to free a section of computer memory when it has finished using it. … Read more

[mental maps] A person’s perception of a place. A mental map may include the physical characteristics of a place, such as boundaries of a neighborhood, or the attributes of a … Read more

[software] A list of available commands or operations displayed on a computer screen from which a user can make a selection.

[software] An item in a list of commands displayed on a menu.

[surveying] Establishing a boundary relative to ground features present at the time of a survey.

[ESRI software] In geodatabases, rules that dictate what happens to the respective attributes of features that are merged together during editing in ArcMap. A merge policy can be set to … Read more

[analysisgeoprocessing] Combining features from multiple data sources of the same data type into a single, new dataset.

A great circle on the earth that passes through the poles, often used synonymously with longitude. Meridians run northsouth between the poles. By convention, meridians are labeled with positive numbers … Read more

Information that describes the content, quality, condition, origin, and other characteristics of data or other pieces of information. Metadata for spatial data may describe and document its subject matter; how, … Read more

[data transfer] A unit of information within metadata, used to describe a particular characteristic of the data.

[ESRI software] A Web application, developed using the ArcIMS Java Connector, that can be used to view metadata included in an ArcIMS metadata service.

[standards] A modification of an existing metadata standard to adapt to data issues, cultural issues, or both. A profile is typically a subset of a base standard that tailors the … Read more

[ESRI software] A public ArcIMS virtual server that provides the capability to manage and search a central metadata repository. Data producers can publish their metadata to the repository while data … Read more

[ESRI software] A service that uses the spatial server metadata capabilities, allowing users to publish and share metadata documents over the Internet or an intranet.

A surveying method in which the limits of a parcel are identified as relative distances and bearings from landmarks. Metes and bounds surveying often resulted in irregularly shaped areas.

[programming] In object-oriented programming, an action that an object is capable of performing. Objects that belong to the same class all have the same methods. For example, all Visual Basic … Read more

[federal government] A geographic entity defined by the U.S. Office of Management and Budget for use by federal statistical agencies, including the U.S. Census Bureau. A metropolitan statistical area is … Read more

[graphics map display] A densitometer that can read densities in minute areas, used particularly for studying spectroscopic and astronomical images.

[physics] An instrument for measuring minute lengths or angles.

[physics] One millionth of a meter, represented by the symbol m. Microns are used to measure wavelengths in the electromagnetic spectrum.

[government] A geographic region containing at least one urban area with a population between 10,000 and 50,000, defined by the U.S. Office of Management and Budget for use by federal … Read more

[programming] Acronym for Mobile Information Device Profile. A set of J2ME APIs for wireless devices.

[defense] The military specification for common war fighting symbology; the U.S. military standard that provides guidelines and criteria for the development and display of standard C4I war fighting symbology.

[ESRI software] An ArcGIS extension that optimizes the effectiveness of core ArcGIS as a toolset foundation for military planners and intelligence analysts. Military Analyst is COM-compliant and extensible with ArcObjects.

[symbology] A symbol that imitates or closely resembles the thing it represents, such as an icon of a picnic table that represents a picnic area.

[ESRI software] The smallest and largest scales at which a layer is visible on a map. Scale ranges are used to prevent detailed layers from displaying when zoomed out and … Read more

[ESRI software] A rectangle, oriented to the x- and y-axes, that bounds a geographic feature or a geographic dataset. It is specified by two coordinate pairs: xmin, ymin and xmax, … Read more

[geocoding] In geocoding, the minimum score a potential match record requires to be considered a candidate. This value is adjustable on the Address Locator Properties dialog box.

The shorter axis of an ellipse or spheroid.

1 [geodesy] An angle equal to 1/60 of a degree of latitude or longitude and containing sixty seconds. 2 [mathematics] An angle equal to 1/60 of a degree of arc.

[ESRI software] In Survey Analyst for field measurements, one of two types of lists in the List page. The mixed list has a mixed set of rows that might have, … Read more

In remote sensing, a pixel whose digital number represents the average of several spectral classes within the area that it covers on the ground, each emitted or reflected by a … Read more

1 [data models] An abstraction of reality used to represent objects, processes, or events. 2 [modeling] A set of rules and procedures for representing a phenomenon or predicting an outcome. … Read more