GIS Dictionary

[ESRI software] Represents a surface that can be drawn to, for example, a screen, bitmap, or printer. In ArcGIS, the Display abstract class is used to abstract a device context.

[graphics computing] The coordinates shown on a digitizer or display, as opposed to those of a recognized datum or coordinate system.

[organizational issues] Acronym for Digital Geographic Information Working Group. A group established in 1983 to develop standards for spatial data exchange among nations participating in the North Atlantic Treaty Organization … Read more

[computing] In geoprocessing, a form consisting of a tool’s parameters.

[output] A way of quickly and inexpensively copying maps using a diazo compound, ultraviolet light, and ammonia.

In image processing, an image made by subtracting the pixel values of one image from those in another.

[GPS] A technique for increasing the accuracy of GPS measurements by comparing the readings to two receiversone roving and the other a fixed base stationand a known location.

[diffusion] The spread of an innovation or technology use among a group of people or organizations.

[standards] Acronym for Digital Geographic Information Exchange Standard. A standard for spatial data transfer among nations, data producers, and data users. The Digital Geographic Information Working Group (DGIWG) developed the … Read more

[mathematics] Represented in discrete, quantified units rather than continuously. Computers process and store information in digital form.

[graphics computing] An image stored in binary form and divided into a matrix of pixels. Each pixel consists of a digital value of one or more bits, defined by the … Read more

[remote sensing] Any technique that changes the digital values of an image for the sake of analysis or enhanced display, such as density slicing or low- and high-pass filtering.

[remote sensing] In a digital image, a value assigned to a pixel.

[data capture] The process of converting the geographic features on an analog map into digital format using a digitizing tablet, or digitizer, which is connected to a computer. Features on … Read more

[data capture] A way of using a digitizing tablet in which locations on the tablet are mapped to specific locations on the screen. Moving the digitizer puck on the tablet … Read more

An algorithm that examines the connectivity of a network to find the shortest path between two points. Dijkstra’s algorithm is named after the Dutch computer scientist Edsger Dijkstra (1930-2002).

[data models] Acronym for Dual Independent Map Encoding. A data storage format for geographic data developed by the U.S. Census Bureau in the 1960s. DIME-encoded data was stored in Geographic … Read more

[physics] A length of a certain distance and bearing.

[ESRI software] One of a number of procedures that dictate what type of dimension feature is created and the number of points required to complete the feature’s geometry. Construction methods … Read more

[ESRI software] In ArcMap, a special kind of geodatabase annotation that shows specific lengths or distances on a map. A dimension feature may indicate the length of a side of … Read more

[ESRI software] A geodatabase feature class that stores dimension features.

[ESRI software] Description of a dimension feature’s symbology, what parts of it are drawn, and how it is drawn. Every time a new dimension feature is created, it is assigned … Read more

[ESRI software] A toolbar in ArcMap that facilitates the creation of dimension features.

[network analysis] In ArcInfo Workstation, an arc between two nodes with one direction specified.

[network analysis] A network state in which edges have an associated direction of flow. In a directed network flow, the resource that traverses a network’s components cannot choose a direction … Read more

[ESRI software] In an ArcGIS vertical coordinate system, an identifier that indicates whether z-values are positive up or positive down. Heights or elevations are usually positive up, against the force … Read more

[ESRI software] In Survey Analyst for field measurements, a field in the computation page that allows the entry of bearings or azimuths between an input survey point and a computed … Read more

In image processing, an edge-detection filter that enhances those linear features in an image that are oriented in a particular direction.

[spatial statistics use for geostatistics] Natural or physical processes that affect a measured trait or attribute so that the magnitude of the effects on the attribute vary in different directions.

[computing] An area of a computer disk that holds a set of data files, other directories, or both. Operating systems use directories to organize data. Directories are arranged in a … Read more

[data quality] Regions surrounding features that have been altered after the initial topology validation process and require additional topology validation to be performed to find any errors.

[network analysis] In geometric networks, an object or shape representing a geographic object through which flow is impossible.

[ESRI software] The process of copying data to another geodatabase, editing that data, then merging the changes with the data in the source or master geodatabase.

[data models] Data that represents phenomena with distinct boundaries. Property lines and streets are examples of discrete data.

[data capture] A method of digitizing in which points are placed individually to define a feature’s shape.

[ESRI software] A feature that has definite feature boundaries.

[data models] A raster that typically represents phenomena that have clear boundaries with attributes that are descriptions, classes, or categories. Generally, integers are used for the cell values. In a … Read more

[hardware] A storage medium for recording digital information, consisting of a round, flat, spinning plate coated with a magnetic material.

[ESRI software] In ArcGlobe, the folder on a computer’s disk drive where ArcGlobe stores layer cache files.

[non-ESRI software] A type of early binding in which DispID properties and methods are accessed at compile time, so there’s no need to call them at run time. DispID binding … Read more

[ESRI software] In ArcGIS, a link created to define the source and destination coordinates for a spatial adjustment. Links are represented as arrows with the arrowhead pointing toward the destination … Read more

[ESRI software] In Survey Analyst – Cadastral Editor, the difference in the coordinates of a point between successive least-squares adjustments. A set of displacement vectors is recorded for a point … Read more

[ESRI software] Often used to refer to subclasses of the Display abstract class. For example, “when drawing to the display” means when drawing to any of the display coclasses; “the … Read more

1 [map projections] The coordinate system used for displaying geographic data. Examples include the data frame in ArcMap and the view in ArcView GIS. 2 [map projections] A pseudo Plate … Read more

[map display] The scale at which data is rendered on a computer screen or on a printed map.

[ESRI software] The mode of command representation on a computer screen. The display type controls whether you see a command’s image, its caption, or both when it appears on a … Read more

[map display] The unit of measure used to render dimensions of shapes, distance tolerances, and offsets on a computer screen or on a printed map. Although they are stored with … Read more

1 [ESRI software] A geoprocessing command that removes boundaries between adjacent polygons that have the same value for a specified attribute. 2 [data editing] The process of removing unnecessary boundaries … Read more

[ESRI software] In linear referencing, a procedure that combines event records in tables where there are events on the same route that have the same value for specified fields. The … Read more

[physics] The measure of separation between two entities or locations that may or may not be connected, such as two points. Distance is differentiated from length, which implies a physical … Read more

[spatial analysis] A mathematical representation of the effect of distance on the accessibility of locations and the number of interactions between them, reflecting the notion that demand drops as distance … Read more

[ESRI software] In the Survey Analyst for field measurements Survey Explorer, a field for entering distance for use in a computation.

[physics] The unit of measurement for distance, such as feet, miles, meters, and kilometers.

On a map or image, the misrepresentation of shape, area, distance, or direction of or between geographic features when compared to their true measurements on the curved surface of the … Read more

[ESRI software] Data spread over multiple platforms or a network by a process referred to as replication.

[database structures] A database with records that are dispersed between two or more physical locations. Data distribution allows two or more people to be working on the same data in … Read more

1 [statistics] The frequency or amount at which a thing or things occur within a given area. 2 [statistics] The set of probabilities that a variable will have a particular … Read more

[graphics computing] The approximation of shades of gray or colors in a computer image made by arranging pixels of black and white or other colors in alternate layers. The technique … Read more

[astronomy] Daily, as in the revolution of the earth.

[astronomy] The apparent path from rise to set made by a heavenly body across the sky.

[data models] Acronym for digital line graph. Data files containing vector representations of cartographic information derived from USGS maps and related sources. DLGs include information from the USGS planimetric map … Read more

[Internet] Acronym for dynamic-link library. A type of file that stores shared code to be used by multiple programs (a “code library”). Programs access the shared code by linking to … Read more

[government] Acronym for Designated Market Area. A television market as defined by Nielsen Media Research. Most DMAs correspond to whole counties, but there are a few exceptions where counties are … Read more

[navigation] Acronym for digital nautical chart. A nautical database developed from existing hard-copy charts, digital data, bathymetric survey information, imagery, and various raster data. DNCs are used by the U.S. … Read more

[Internet] Acronym for domain name system. The Internet distributed system that stores IP addresses and domain names to assist with the routing of network traffic.

[computing] A window that can exist in a floating state or be attached to the main application window.

[computing] Moving a floating toolbar or window to a fixed location in the graphical user interface.

[ESRI software] A component of an ArcView 3.x project. Each document type (view, table, chart, layout, script) has its own window and interface.

[ESRI software] Supporting information for software data and tools. Documentation may be descriptive or instructional, and is published in a variety of formats, including user’s guides and manuals, desktop help … Read more

[ESRI software] In geoprocessing, the interface used to write documentation for tools, toolsets, toolboxes, and processes within a model.

1 [data transfer] The range of valid values for a particular metadata element. 2 [computing] A group of computers and devices on a network that are administered as a unit … Read more

[Internet] The unique name of a computer system on the Internet, such as “esri.com.”

[spatial analysis] A method of defining the rings in an analysis so that the values inside the rings are exclusive. For example, in an analysis with three donut rings and … Read more

[GPS] Acronym for dilution of precision. An indicator of satellite geometry for a constellation of satellites used to determine a position. Positions with a lower DOP value generally constitute better … Read more

[physics] The apparent change in frequency of sound or light waves caused by the relative motion between a source and an observer. As they approach one another, the frequency increases; … Read more

[GPS] Signal processing that uses a measured Doppler shift to help the receiver track the GPS signal.

[aerial photography] Acronym for digital orthophoto quadrangle. A computer-generated, uniform-scale image created from an aerial photograph. Digital orthophoto quadrangles are true photographic maps in which the effects of tilt and … Read more

[navigation] Acronym for digital orthophoto quarter quadrangle. A digital orthophoto quadrangle (DOQ) divided into four quadrants.

[cartography] A quantitative, thematic map on which dots of the same size are randomly placed in proportion to a numeric attribute associated with an area. Dot density maps convey the … Read more

[cartography] A map that uses dots or other symbols to represent the presence, quantity, or value of a phenomenon or thing in a specific area. In a dot distribution map, … Read more

[printing] A photographic film covered with uniformly sized, evenly spaced dots used to break up a solid color, producing an apparently lighter color.

[computing] The level of coordinate exactness based on the possible number of significant digits that can be stored for each coordinate. Datasets can be stored in either single or double … Read more

[computing] The level of coordinate exactness based on the possible number of significant digits that can be stored for each coordinate. Datasets can be stored in either single or double … Read more

An algorithm that simplifies complex lines by reducing the number of points used to represent them. The Douglas-Peucker algorithm was developed by the Canadian geographers David H. Douglas and Thomas … Read more

[network analysis] In network tracing, the direction along a line or edge that is the same as the direction of flow.

[graphics computing] Acronym for dots per inch. A measure of the resolution of scanners, printers, and graphic displays. The more dots per inch, the more detail can be displayed in … Read more

[cartography] A method of drawing with pencil or pen and ink, used in cartographic reproduction.

All map features associated with the movement and flow of water, such as rivers, streams, and lakes.

[ESRI software] A layer in ArcGlobe that has been categorized to be draped on top of the globe surface.

[data models] Acronym for digital raster graphic. A raster image of a scanned USGS standard series topographic map, usually including the original border information, referred to as the map collar, … Read more

[spatial statistics use for geostatistics] The general pattern of z-values throughout a kriging model. The drift, or structure, forms the model’s basic shape.

[spatial analysis] A zone around a map feature measured in units of time needed for travel by car. For example, a store’s 10-minute drive-time area defines the area in which … Read more

A type of scanner in which a hard-copy image or map is attached to a cylinder that spins while a sensor captures a digital image from the surface of the … Read more

[data models] Acronym for digital surface model. The representation of continuous elevation values over a topographic surface, including vegetation and man-made features, by a regular array of z-values, referenced to … Read more

[programming] Acronym for document type definition. A set of rules that define the allowed structure and properties of XML documents.

[data models] Acronym for digital terrain elevation data. A format for elevation data, usually tiled in 1-degree cells, produced by the National Geospatial-Intelligence Agency and U.S. allies for military applications.

[ESRI software] Labels with identical content. Maplex for ArcGIS provides the option of labeling only a single feature out of a cluster of similar features. Identical labels will not be … Read more

[ESRI software] A feature class consisting of points associated with address elements in an address data table that change based on changes made to the address data table.

[Internet] An extension to HTML that allows Web designers to make elements on a Web page interactive, rather than changeable only when the page is loaded.

[data analysis] The process of computing the map locations of linearly referenced data (for example, attributes stored in a table) at run time so they can be displayed on a … Read more