GIS Dictionary

[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.