GIS Dictionary

[statistics] A ratio of variances, calculated from a sample of data and used to provide information about a whole dataset. For example, statistic F may be used to provide estimates … Read more

[statistics] A statistical test for determining the probability that the variances of two different samples are the same. The F test uses a statistic known as statistic F to test … Read more

[Euclidean geometry] A planar surface of a geometric shape, bounded by edges.

[ESRI software] In ArcGIS Network Analyst, a network location used in closest facility and service area analyses.

[map projections] The linear value added to all x-coordinates of a map projection so that none of the values in the geographic region being mapped are negative.

[map projections] The linear value added to all y-coordinates of a map projection so that none of the values in the geographic region being mapped are negative.

[cartography] A representation of a real-world object on a map.

[ESRI software] In ArcGIS, a collection of geographic features with the same geometry type (such as point, line, or polygon), the same attributes, and the same spatial reference. Feature classes … Read more

[ESRI software] Data that represents geographic features as geometric shapes.

[ESRI software] In ArcGIS, a collection of feature classes stored together that share the same spatial reference; that is, they share a coordinate system, and their features fall within a … Read more

[graphics map display] The movement of features that would otherwise overprint or conflict with other features. For example, if a river, a road, and a railway run through a narrow … Read more

[digital image processing] In image processing, a method of pattern recognition in which patterns within an image are measured and then classified as features based on those measurements.

[data analysis] A layer that references a set of feature data. Feature data represents geographic entities as points, lines, and polygons.

[ESRI software] A public ArcIMS virtual server for feature services.

[ESRI software] The process of delivering vector feature data defined for a service that uses the feature server component. On the client side, feature streaming allows you to access a … Read more

[ESRI software] A collection of default settings for creating a feature, including the layer where the feature will be stored, the attributes the feature will have, and the default tool … Read more

[ESRI software] In ArcMap, a ranking system that indicates whether features from a given feature class may be covered by a label in cases where the label cannot be placed … Read more

[ESRI software] Annotation that is stored in the geodatabase with links to features through a geodatabase relationship class. Feature-linked annotation reflects the current state of features in the geodatabase: it … Read more

[organizational issues] Acronym for Federal Geographic Data Committee. An organization established by the United States Federal Office of Management and Budget responsible for coordinating the development, use, sharing, and dissemination … Read more

1 [database structures] A column in a table that stores the values for a single attribute. 2 [computing] The place in a database record, or in a GUI, where data … Read more

[analysisgeoprocessing] In geoprocessing, defining the field structure and content for an output dataset.

[ESRI software] The number of digits that can be stored in a field in a table.

[ESRI software] The number of decimal places for float or double-type geodatabase table fields.

[cognition] A philosophical view of geographic space in which space is completely filled by occurrences of phenomena, and in which phenomena are described by a range of values on a … Read more

[computing] A collection of uniquely named information stored on a drive, disk, or tape. A file generally resides within a directory.

[database structures] A geodatabase stored as a folder of files. A file geodatabase can be used simultaneously by several users, but only one user at a time can edit the … Read more

[computing] The name that distinguishes a file from all other files in a particular directory. It can refer to the name of the file by itself (harold), the name plus … Read more

[computing] The abbreviation following the final period in a file name that indicates the file’s format, such as .shp, .zip, or .tif. File name extensions are usually one to four … Read more

1 [map display] The interior of a polygon; the area inside the perimeter. 2 [ESRI software] In MOLE, the graphic component inside the frame that forms the background.

[symbology] A color or pattern used to fill polygons on a map.

[data analysis] A segment of a circle used to connect two intersecting lines. Fillets are used to create smoothly curving connections between lines, such as pavement edges at street intersections … Read more

1 [spatial analysis] On a raster, an analysis boundary or processing window within which cell values affect calculations and outside which they do not. Filters are used mainly in cell-based … Read more

[data analysis] A process that seeks out new market areas based on the characteristics of an existing market area.

[database structures] The first level of guidelines for designing table and data structures in a relational database. The first normal form guideline recommends creating a unique key for every row … Read more

The degree to which a dataset is suitable for a particular application or purpose, encompassing factors such as data quality, scale, interoperability, cost, data format, and so on.

[geodesy] A single position obtained by surveying, GPS, or astronomical measurements, usually given with altitude, time, date, and latitude-longitude or grid position.

[ESRI software] In Survey Analyst for field measurements, a survey point used as an input to a computation. The coordinates are not updated by the computation.

[ESRI software] In ArcGIS Tracking Analyst, stored temporal data that can be viewed in past, future, and past-and-future time windows. This data is stored in a shapefile or as a … Read more

1 [graphics map display] A marker that identifies or calls attention to something, indicating importance or the need for further attention. 2 [ESRI software] In ArcMap, a temporary graphic that … Read more

[Internet] A browser-independent, vector graphic technology for creating interactive Web sites with video, graphics, and animation. Browsers need plug-ins for Flash animations.

A type of scanner with a flat, clear surface on which a map or image remains stationary while a sensor beam moves across it and captures a digital image.

A measure of how much an oblate spheroid differs from a sphere. The flattening equals the ratio of the semimajor axis minus the semiminor axis to the semimajor axis.

[Internet] A set of tools that allows developers to create cross-platform, browser-independent Web applications using a standards-based programming language. Created by Macromedia in 2004 and now developed by Adobe, the … Read more

[ESRI software] A layer in ArcGlobe that has been categorized to float independently above or below the globe surface.

[computing] A type of numeric field for storing real numbers with a decimal point. The decimal point can be in any position in the field and, thus, may “float” from … Read more

[network analysis] The route or course followed by commodities proceeding through edge elements in a network.

[cartography] A map that uses line symbols of variable thickness to show the proportion of traffic or flow within a network.

[data analysis] The computation of an output raster where the output value at each cell location is a function of the value at that cell location and the values of … Read more

[ESRI software] In Survey Analyst for field measurements, the field that is the current target for data entry.

[ESRI software] In ArcCatalog, a top-level item in the Catalog tree that provides quick access to geographic data stored on local disks (including CD-ROMs) or shared on a network. Folder … Read more

[ESRI software] In ArcGIS, a method for placing geodatabase annotation relative to a line or polygon feature. For example, text next to a river may be dragged along it so … Read more

[graphics map display] A single typeface or a set of related patterns representing characters or symbols at one size.

[data structures] The extent (often rectangular) of each raster dataset in the mosaic dataset or image service definition. This outline is not always the extent of each raster dataset but … Read more

[ESRI software] In MOLE, a component of a map display that shows where force units are located so that the map reader can see where forces are the strongest and … Read more

[ESRI software] In MOLE, a type of graphic that represents a military unit (such as Company A, 1st Battalion of the 135th Infantry), equipment, or installation (such as a hospital … Read more

1 [map display] In a scene or display, the area that appears to be closest to an observer. 2 [ESRI software] The area in a raster layer where cells are … Read more

[database structures] An attribute or set of attributes in one table that match the primary key attributes in another table. Foreign keys and primary keys are used to join tables … Read more

[cartography] Lines on a map that approximate the shape of terrain in lieu of actual contours. Form lines do not refer to a true datum and do not necessarily use … Read more

[computing] In computing, the structure and organization of digital information.

[mathematics] A geometric pattern that repeats itself, at least roughly, at ever smaller scales to produce self-similar, irregular shapes and surfaces that cannot be represented using classical geometry. If a … Read more

1 [ESRI software] In MOLE, the geometric border of a graphic that indicates the affiliation, battle dimension, and status of the war fighting element that the MOLE graphic represents. 2 … Read more

[computing] The existing ArcObjects components that comprise the ArcGIS system.

[ESRI software] In Survey Analyst for field measurements, one of two phases involved when performing a least squares adjustment for a measurement network. The free network adjustment phase examines the … Read more

[ESRI software] In ArcGIS, the representation of a single feature that has been disconnected from its representation rule to create an independent rule whose structure can be changed, allowing full … Read more

[ESRI software] To fix a column in place in a table for better viewing of the table’s contents. A frozen column will stay in place while the other columns scroll … Read more

[physics] The number of oscillations per unit of time in a wave of energy, or the number of wavelengths that pass a point in a given amount of time.

Of an arc’s two endpoints, the first one digitized. From- and to-nodes give an arc left and right sides and, therefore, direction.

[non-ESRI software] Acronym for File Transfer Protocol. A protocol that allows the transmission of files between computers over a network.

[ESRI software] In ArcGlobe, a layer cache saved on disk that contains complete levels of details for the entire layer.

1 [analysisgeoprocessing] An operation. In GIS, functions include data input, editing, and management; data query, analysis, and visualization; and output operations. 2 [analysisgeoprocessing] Processing operation applied to rasters or mosaic … Read more

[analysisgeoprocessing] An ordered list of functions applied to a raster or mosaic dataset that are performed as the data is accessed.

[ESRI software] In 3D Analyst, a surface that stores a single z-value for any given x,y location.

[uncertainty] A boundary that has a vague or indeterminate location, or that is a gradual transition between two zones.

[uncertainty] Any method for classifying data that allows attributes to apply to objects by membership values, so that an object may be considered a partial member of a class. Class … Read more

In mathematics, a collection of elements that belong together based on specified criteria, so that elements with partial or uncertain degrees of membership may be included in the collection.

[ESRI software] The distance within which coordinates of nearby features are adjusted to coincide with each other when topology is being constructed or polygon overlay is performed. Nodes and vertices … Read more