GIS Dictionary

[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.