GIS Dictionary

[statistics] A statistic computed by the regression equation to quantify model performance. The value of R-squared ranges from 0 to 100 percent. If a model fits the observed dependent variable … Read more

A tree data structure, similar to a B-tree, used for indexing spatial data within a database. In an R-tree structure, data is sorted into a set of hierarchical nodes that … Read more

[physics] Acronym for radio detection and ranging. A device or system that detects surface features on the earth by bouncing radio waves off them and measuring the energy reflected back.

[physics] An instrument that determines elevation, usually from mean sea level, by measuring the amount of time an electromagnetic pulse takes to travel from an aircraft to the ground and … Read more

[remote sensing] The analysis of interferograms that have been created by IFSAR, or artificially. Radar interferometry involves the comparison of two or more images of the same area taken from … Read more

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

[Euclidean geometry] The angle subtended by an arc of a circle that is the same length as the radius of the circle, approximately 57 degrees, 17 minutes, and 44.6 seconds. … Read more

[physics] The emission and propagation of energy through space in the form of waves. Electromagnetic energy and sound are examples of radiation.

[physics] An instrument that measures the intensity of radiation in a particular band of wavelengths in the electromagnetic spectrum, such as infrared or microwave.

[remote sensing] Procedures that correct or calibrate aberrations in data values due to specific distortions from such things as atmosphere effects (such as haze) or instrumentation errors (such as striping) … Read more

[physics] The sensitivity of a sensor to incoming reflectance. Radiometric resolution refers to the number of divisions of bit depth (for example, 255 for 8-bit, 65,536 for 16-bit, and so … Read more

[Euclidean geometry] The distance from the center to a point on the outer edge of a circle, circular curve, or sphere.

[spatial statistics use for geostatistics] In a spatial model, variation in the value of a variable that cannot be described by a mathematical function and is not spatially correlated: it … Read more

A parameter of a variogram or semivariogram model that represents a distance beyond which there is little or no autocorrelation among variables.

[data structures] A type of attribute domain that defines the range of permissible values for a numeric attribute. For example, the permissible range of values for a pipe diameter could … Read more

[accuracy] A method of assigning an accuracy value to feature classes to avoid having vertices from a feature class collected with a high level of accuracy being snapped to vertices … Read more

1 [data models] A spatial data model that defines space as an array of equally sized cells arranged in rows and columns, and composed of single or multiple bands. Each … Read more

[ESRI software] An ArcGIS Spatial Analyst tool for performing mathematical calculations with operators and functions, setting up selection queries, or typing Map Algebra syntax. Inputs to the Raster Calculator can … Read more

[ESRI software] A collection of raster datasets defined in a table of any format, in which the records define the individual raster datasets that are included in the catalog. Raster … Read more

[ESRI software] The process of drawing, filling, and erasing raster cells using ArcScan Raster Cleanup and Raster Painting tools.

[data models] A representation of the world as a surface divided into a regular grid of cells. Raster models are useful for storing data that varies continuously, as in an … Read more

[data models] In ArcGIS, a raster spatial data model that is stored on disk or in a geodatabase. Raster datasets can be stored in many formats, including TIFF, JPEG 2000, … Read more

[remote sensing] One layer in a raster dataset that represents data values for a specific range in the electromagnetic spectrum (such as ultraviolet, blue, green, red, and infrared), or radar, … Read more

[data models] Three or more lines in a raster that meet at a common point.

[ESRI software] In ArcGIS, a layer that references a raster as its data source and a raster renderer that defines how the raster data should be rendered and any additional … Read more

[data conversion] In ArcScan, the automatic correction of vector feature results immediately after batch vectorization is completed. Postprocessing involves generalizing lines, straightening angles, and smoothing lines.

[data conversion] Simple raster editing that prepares images for viewing and analysis. Preprocessing includes georeferencing, clipping, positioning, resizing, enhancing, and mosaicking.

[ESRI software] In ArcGIS Image Server, an XML file that contains properties of the raster dataset, including metadata, as well as the definition of processes to be applied to one … Read more

[ESRI software] Statistics that are calculated from the cell values of each band in a raster. The statistics that are calculated include the minimum, maximum, mean, and standard deviation cell … Read more

[data conversion] An interactive vectorization process that involves drawing along the boundary of contiguous raster cells to create vector features.

[data models] In ArcGIS, identifies metadata, such as georeferencing, acquisition date, and sensor type, along with a raster format.

[data conversion] The conversion of points, lines, and polygons into cell data.

[ESRI software] A feature layer in ArcGlobe that exists as points, lines and polygons but is rendered as cell data. When layers are added to ArcGlobe, they may automatically be … Read more

[data structures] Data classified relative to a fixed zero point on a linear scale. Mathematical operations can be used on these values with predictable and meaningful results. Examples of ratio … Read more

In digital image processing, enhancing the contrast between features in an image by dividing the values of pixels in one image by the values of corresponding pixels in a second … Read more

[3D GIS] A technique that traces imaginary rays of light from a viewer’s eye to the objects in a three-dimensional scene to determine which parts of the scene should be … Read more

[database structures] Acronym for relational database management system. A type of database in which data is organized across one or more tables. Tables are associated with each other through common … Read more

[data capture] Data that is displayed immediately, as it is collected. Real-time data is often used for navigation or tracking.

[ESRI software] The time mode in ArcGIS Tracking Analyst in which data is automatically displayed on the map after being added.

[spatial analysis] The process of taking input cell values and replacing them with new output cell values. Reclassification is often used to simplify or change the interpretation of raster data … Read more

[database structures] In concurrency management, to merge all modified data in the current database edit session with a second version of the data.

1 [database structures] A set of related data fields, often a row in a database, containing all the attribute values for a single feature. For example, in an address database, … Read more

[data conversion] The process of applying a mathematical transformation to an image so that the result is a planimetric image.

1 [mathematics] Characterized by straight lines, usually parallel to orthogonal axes. 2 [map design] A map or image whose horizontal and vertical scales are identical.

[programming] The process by which server instances in a pool are replaced by new instances of services. Recycling allows services that have become unusable to be destroyed and replaced with … Read more

[government] The process of revising the boundaries of administrative, legislative, or election districts.

[ESRI software] In Survey Analyst, occurs when the number of observed measurements is greater than the number of computed coordinates in a measurement network.

[programming] A pointer to an object, interface, or other item allocated in memory. COM objects keep a running total of the references to themselves via the IUnknown interface methods AddRef … Read more

[geocoding] In geocoding, material containing the location and address information of specific features. Reference data consists of the spatial representation of the data and the related attribute table.

[ESRI software] In ArcGIS, a spatial data layer that a geocoding service uses to perform address geocoding. A reference data source can be any point, line, or polygon feature class … Read more

[ESRI software] In ArcGIS, a spatial data layer that a geocoding service uses to perform address geocoding. A reference data source can be any point, line, or polygon feature class … Read more

[geodesy] Any datum, plane, or surface from which other quantities are measured.

[geodesy] Any datum, plane, or surface from which other quantities are measured.

[geodesy] An ellipsoid associated with a geodetic reference system or geodetic datum.

[map design] A map designed to show where geographic features are in relation to each other.

[ESRI software] In Survey Analyst, a point with known coordinates, used as input to a computation.

[symbology] The scale at which symbols appear on a digital page at their true size, specified in page units. As the extent is changed, text and symbols will change scale … Read more

[coordinate systems] A method for identifying positions on the globe. This is often constructed with a grid that either refers to the earth’s latitude and longitude (graticule), or a planar … Read more

[ESRI software] In ArcView 3.x, a theme used to perform geocoding. A reference theme can be any point, line, or polygon theme that contains the necessary address fields. Each address … Read more

[ESRI software] In Survey Analyst, occurs when a copy of a coordinate from a different project is added to the survey point for exclusive use in your project. When this … Read more

[ESRI software] A DBMS-defined restriction that ensures that foreign key values in the rows in the child table always have matching primary key values in the parent table.

[data quality] A mechanism for ensuring that data remains accurate and consistent as a database changes. When changes are made to a table related to another table by a common … Read more

[physics] The proportion of incident radiant energy that is reflected by a surface. Reflectance varies according to the wavelengths of the incident radiant energy and the color and composition of … Read more

[non-ESRI software] A utility, part of the Windows operating system, that allows you to view and edit the system registry.

1 [geography] In geography, an area usually distinguished by common cultural or physical characteristics, such as Southern California, Western Europe, or Southeast Asia. 2 [data models] A set of contiguous … Read more

1 [data editing] To align two or more maps or images so that equivalent geographic coordinates coincide. 2 [geolocating] To link map coordinates to ground control points. 3 [software] In … Read more

[ESRI software] A three-letter, nine-digit number (ABC123456789, for example) that authenticates software with ESRI. Every single use and server product, including their extensions or options, has a unique registration number.

[computing] Stores information about system configuration for a Windows machine. COM uses the registry extensively, storing details of COM components including ProgIDs and ClassIDs, file location of the binary code, … Read more

[software] A file containing information in Windows Registry format. Double-clicking a .reg file in Windows will enter the information in the file into the system registry. Often used to register … Read more

[statistics] A statistical method for evaluating the relationship between a single dependent variable and one or more independent variables thought to influence the dependent variable. Regression is used to predict … Read more

[statistics] A value associated with each independent variable in a regression equation, representing the strength and type of relationship the independent variable has to the dependent variable. For example, fire … Read more

[statistics] The mathematical formula applied to independent variables to best predict the dependent variable being modeled. The notation in regression equations is always Y for the dependent variable and X … Read more

[software] A Windows utility that registers a DLL or similar component library to a system registry. A DLL and its components must be registered before it can be used.

[programming] In programming, to reinstantiate an object and its state from persisted storage.

[geocoding] Handling unmatched addresses through fine-tuning the geocoding process. After a table of addresses are matched the first time, unmatched addresses can be reviewed or edited. Reject processing attempts to … Read more

[database structures] An operation that establishes a temporary connection between records in two tables using a key common to both.

[ESRI software] An ArcToolbox utility used to build, modify, save, and delete connections (relates) between tables. Saved connections can be reactivated in future ArcToolbox sessions.

[database structures] A data structure in which collections of tables are logically associated with each other by shared fields.

1 [ESRI software] In ArcGIS Spatial Analyst, an operator that evaluates specific relational conditions. If a condition is TRUE, the output is assigned a value of 1. If the condition … Read more

[database structures] An association or link between two objects in a database. Relationships can exist between spatial objects (features), between nonspatial objects (rows in a table), or between spatial and … Read more

[database structures] An item in the geodatabase that stores information about a relationship. A relationship class is visible as an item in the ArcCatalog tree or contents view.

[accuracy] A measure of positional consistency between a data point and other, near data points. Relative accuracy compares the scaled distance of objects on a map with the same measured … Read more

[navigation] A bearing measured relative to a vessel or aircraft’s heading.

[map projections] Coordinates identifying the position of a point with respect to another point.

[computing] In computing, the location of a computer file given in relation to the current working directory.

[ESRI software] In geodatabase editing, the other replica in a replica pair of parent and child. The relative replica to a child replica is the parent replica, and vice versa.

[cartography] A map element that contains a simplified view of the sources used to compile a map.

[cartography] Elevations and depressions of the earth’s surface, including those of the ocean floor. Relief can be represented on maps by contours, shading, hypsometric tints, digital terrain modeling, or spot … Read more

[geocoding] The process of regeocoding a feature or features in a geocoded feature class.

[remote sensing] Collecting and interpreting information about the environment and the surface of the earth from a distance, primarily by sensing radiation that is naturally emitted or reflected by the … Read more

[remote sensing] Imagery acquired from satellites and aircraft, including panchromatic, radar, microwave, and multispectral satellite imagery.

[graphics computing] A mechanism that defines how data appears when displayed. For example, the hillshade renderer for raster data in ArcMap calculates and applies shading based on existing data values … Read more

[graphics computing] The process of drawing to a display; the conversion of the geometry, coloring, texturing, lighting, and other characteristics of an object into a display image.

[ESRI software] In 3D Analyst, a tab on the Layer Properties dialog box that allows users to control whether or not a layer is displayed during scene navigation, how it … Read more

[ESRI software] The isolation level in a database management system (DBMS) that ensures that when the same rows are read multiple times during the course of a transaction, the returned … Read more

[ESRI software] In geodatabase editing, the portion of the data in a geodatabase that is copied from a source geodatabase to a destination geodatabase during the replication process. The replica … Read more

[ESRI software] In geodatabase editing, each combination child and parent replica.

[ESRI software] An XML file that describes schema differences between the data in a replica and its relative replica.

[ESRI software] A workspace document file that describes the schema of the data in a replica.

[ESRI software] In geodatabase editing, the version being replicated during the replication process. For all replica types, the replica version for a parent replica is the version the user was … Read more