GIS Terms

North Arrow

A map symbol that shows the direction of north on the map, thereby showing how the map is oriented.

Mask

A means of identifying areas to be included in analysis. Such a thing is often referred to as an analysis mask, and may be either a raster layer or feature layer.

Relate

Establishing a connection between two tables using an attribute that is common to both.

Kernel density

Calculates a magnitude-per-unit area from point or polyline features using a kernel function to fit a smoothly tapered surface to each point or polyline.

Scale bar

A map element used to geographically represent the scale of a map. A scale bar is typically a line marked like a ruler in units proportional to the maps's scale.

Geocoding

A GIS operation for converting street addresses into spatial data that can be displayed as features on a map, usually by referencing address information from a street segment data layer.

Geoprocessing

A GIS operation used to manipulate GIS data. A typical geoprocessing operation takes an input dataset, performs an operation on that dataset, and returns the result of the operation as an output dataset. Common geoprocessing operations include geographic feature overlay, feature selection and analysis, topology processing, raster processing, and data conversion. Geoprocessing helps define, manage, and analyze the information used to form decisions.

Geometric Interval Classification

A classification scheme in which the class breaks are based on class intervals that are in a geometric series. The gemoetric coefficient in this classifier can change once (to its inverse) to optimize class ranges.

Feature dataset

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 common geographic area. Feature classes of different geometry types can be stored in this term.

Layout

A collection of organized elements. IN a layout, common elements, including the map, map labels, a title, legend, scale bar, north arrow, captions, and additional graphics can be arranged.

Clip

A command that extracts features from one feature class that resides entirely within a boundary defined by features in another feature class.

Map frame

A container for maps on your layout, which can reference any map or scene in your project. Empty map frames can be used when creating templates. The map extent of this thing is independent of any map view in the project. A dataset can be represented in one or more of these things. IN map view, only one of these is displayed at a time; on a layout multiple map frames can be displayed at the same time.

Vector

A coordinate system-based model that represents geographic features as points, lines, or polygons. Each point feature is represented as a single coordinate pair, and line and polygon features are represented as ordered lists of vertices. Attributes are associated with each ______ feature, as opposed to a raster model, which associates attributes with grid cells.

Quantile classification

A data classification method that distributes a set of values into groups that contain an equal number of values.

Equal interval classification

A data classification method that divides a set of attribute values into groups that contain an equal range of values.

Standard deviation classification

A data classification method that finds the mean value, and then replaces a class breaks above and below the mean at intervals of either .25, .5 or 1 standard deviation until all the data values are contained within the classes Values that are beyond three standard deviations from the mean are aggregated into two classes-greater than three standard deviations above the mean and less than three standard deviations below the mean.

Geodatabase

A database or file structure used primarily to store, query, and manipulate spatial data. These store geometry, a spatial reference system, attributes, and behavioral rules for data. The data for these can include feature classes, attribute tables, raster datasets, network datasets, topologies,a nd many others. They can be stored in IBM DB2, IBM Informix, Oracle, SQL Server, and ProgreSQL relational database managemetn systems or in a system of files.

Address Locator

A dataset in ArcGIS that stores the address attributes, associated indexes, and rules that define the process for translating nonspatial descriptions of places, such as street addresses, into spatial data that can be displayed as features on a map. An address locator contains a snapshot of the reference data used for geocoding and includes the parameters for standardizing addresses, searching for match locations, and creating output.

Layer package

A file (.lpkx) that includes both the layer properties and the source data referenced by the layer. These contain symbolization, labeling, table properties, and the data. They can be created and viewed in ArcGIS Pro, ArcMap, ArcGlobe, and ArcScene, as well as viewed in ArcGIS Online.

Layer file

A file witha .lyrx extention that stores the path to a source dataset and other layer properties, including symbology

Python

A free, cross-platform, open-source programming language that is embedded in ArcGIS products and used for geoprocessing scripting.

Intersect

A geometric integration of spatial datasets that preserves features or portions of features that fall within areas that are common to all input datasets.

Map algebra

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 operators are a combination of mathematical, logical, or Boolean operators (+, >, AND, tan, and so on), and spatial analysis functions (slope, shortest path, spline, and so on), and the operands are spatial data and numbers.

Edge

A line between two points that forms a boundary

Basemap

A map depicting background reference information, such as landforms, roads, landmarks, political boundaries, or satellite imagery, onto which other thematic information is placed.

Feature template

A named set of tools that creates new features. Items corresponding to this term contain properties that you can configure and define how a new feature is created.

Command line

A programming environment in which the user enters commands by means of strings of text typed on a keyboard, as opposed to selecting commands from graphic prompts such as icons or dialogue boxes.

Coordinate system

A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions. The Cartesian and the geographic systems used on the earth's surface are common examples.

Geographic Coordinate System

A reference system that uses latitude and longitude to define the locations of points on the surface of a sphere or spheroid. A geographic coordinate system definition includes a datum, prime meridian, and angular unit.

Projected coordinate system

A reference system used to locate x,y, and z positions of point, line, and area features in two or three dimensions. A _________ is defined by a geographic coordinate system, a map projection, any parameters needed by the map projection, and a linear unit of measure.

Layer

A reference to a data source, such as a shapefile, coverage, geodatabase feature class, or raster, that defines how the data should be symbolized on a map. They can also define additional properties, such as which features from the data source are included.

Attribute query

A request for records of features in a table based on their attribute values.

Definition query

A request that examines feature or tabular attributes based on user-selected criteria and displays only those features or records that satisfy the criteria.

Space-time cube

A set of points summarized into a data structure by aggregating them into space-time bins that form a cube. Within each bin, the points are counted, and specified attributes are aggregated.

Task

A set of preconfigured steps that guide you and others through a workflow or business process. A task can be used to implement a best-practice workflow, improve the efficiency of a workflow, or create a series of interactive tutorial steps. _______ reside in ______ items, which are stored within an ArcGIS Pro project.

Script

A small program or sequence of instructions, or the act of writing such a program; in ArcGIS, ______ are written using Python in a programming environment known as ArcPy.

Raster

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 cell contains an attribute value and location coordinates. Unlike a vector structure, which stores coordinates explicitly, raster coordinates are contained in the ordering of the matrix. Groups of cells that share the same value represent the same type of geographic feature.

Location Query

A statement or logical expression that selects geographic features based on location or spatial relationship. For example, a spatial query might find which points are contained within a polygon or set of polygons, find features within a specified distance of a feature, or find features that are adjacent to each other.

Query expression

A type of expression that evaluates to a Boolean (true or false) value and is typically used to select those rows in a table whose values cause the expression to evaluate to true. Query expressions are generally part of a SQL statement.

Spatial join

A type of table join operation in which fields from one layer's attribute table are appended to another layer's attribute table based on the relative locations of the features in the two layers.

Shapefile

A vector data storage format for storing the location, shape, and attributes of geographic features. A ______ is stored in a set of related files and contains one feature class.

Graduated colors

A way to symbolize map features in which a range of colors indicates a progression of numeric values. For example, increases in population density might be represented by the increased saturation of a single color, or temperature differences might be shown by a sequence of colors from blue to red.

Graduated symbols

A way to symbolize point or line features according to the value of the attribute they represent. For example, denser populations might be represented by larger dots or larger rivers by thicker lines.

Buffer

A zone around a map feature measured in unites of distance or time. They are useful for proximity analysis.

GIS

Acronym for geographic information system. An integrated collection of computer software and data used to view and manage information about geographic places, analyze spatial relationships, and model spatial processes. A GIS provides a framework for gathering and organizing spatial data and related information so that it can be displayed and analyzed.

Defined interval classification

Also known as a class interval. A set of categories for classification that divide the range of all values so that each piece of data is contained within a nonoverlapping category.

Organization

An ArcGis online _______ is shared workspace composed of users, items, and groups. Users can view, contribute, and share web layers, maps, and other content.

Map view

An all-purpose view for exploring, displaying and querying geographic data. This view does not show any map elements, such as titles, north arrow, and scale bars

alias

An alternative name specified for fields, tables, files, or datasets that is more descriptive and user-friendly than the actual name.

Hot spot analysis

An analysis that attempts to identify statistically significant spatial clusters of high values (hot spots) and low values (cold spots)

ArcGIS Pro

An application for creating and working with spatial data on your desktop. It provides tools to visualize, analyze compile, and share your data, in both 2D and 3D environments.

Snapping

An automatic editing operation in which points or features within a specified distance (tolerance) of other points or features are moved to match or coincide exactly with each other's coordinates.

Near

An operation that calculates distance and additional proximity information between the input features and the closest feature in another layer or feature class.

Style

An organized collection of predefined colors, symbols, properties of symbols, and map elements. _____ promote standardization and consistency in mapping products.

on-the-fly projection

ArcMap can display data stored in this projection as if it was in another projection. The new projection is used for display and query purposes only. The actual data is not altered.

Continuous data

Data such as elevation or temperature that varies without discrete steps. Because computers store data discretely, this is usually represented by triangulated irrelgular networks (TINs), rasters, or contour lines, so that any location has either a specified value or one that can be derived.

Open Data

Data that is licensed to permit people to use the data freely. This data can be reused, redistributed, and shared-even commercially.

Temporal data

Data that represents a state in time. Time values are stored in a single attribute field and can be used to visualize features or phenomena at moments on the timeline.

Discrete data

Data that represents phenomena with distinct boundaries. Property lines and land-use areas are examples of discrete data.

Project

In ArcGIS Pro, a collection of related geographic datasets, maps, layouts, tools, settings, and resources. A _____ is stored as an item in ArcGIS online or on disk as an .aprx fiile.

Web layer

In ArcGIS online, web layers are desinged for map visualization, editing, and querying and consist of two types: feature layers and tile layers. Feature layers support vector data and are most appropriate for visualizing data on top of basemaps. Tile layers are a collection of predrawn map images, or tiles, and are most appropriate for basemaps.

feature class

In ArcGIS, a collection of geographic features that have the same geometry type (such as point, line, or polygon), the same attributes, and the same spatial reference. These can be stored in a geodatabase, shapefile, or coverage among other data formats. They allow homogeneous features to be grouped into a single unit for data storage purposes.

Edit sketch

In ArcGIS, a temporary feature sketch for creating new features or editing existing feature geometry. Edit sketches that are saved become permanent.

Label

In ArcGIS, descriptive text, usually based on one or more feature attributes. These are placed dynamically or near features based on user-defined rules and in response to changes in the map display. These cannot be individually selected and modified by the user. Placement rules and display properties (such as font size and color) are defined for an entire layer.

Azimuth

In GIS software, the direction from which a light source illuminates a surface.

Attribute domain

In a geodatabase, a mechanism for enforcing data integrity. Attribute domains define what values are allowed in a field in a feature class or a nonspatial attribute table. If the features or nonspatial objects are grouped into subtypes, different attribute domains can be assigned to each of the subtypes.

Overlay

In geoprocessing, the geometric intersection of multiple datasets to combine, erase, modify, or update features in a new output dataset.

NoData

In raster data, the absence of a recorded value. This does not equate to a zero (0) value. Although the measure of an attribute in a cell may be zero, a NoData value indicates that no measurement has been taken for that cell at all.

Metadata

Information that describes the content, quality, condition, origin, and other characteristics of data or other pieces of information. For spatial data, this may describe and document its subject matter; how , when, where, and by whom the data was collected; availability and distribution of information; its projection, scale, resolution, and accuracy; and its reliability regarding some standard. It consists of properties and documentaiton. Properties are derived from the data source (for example, the coordinate system and projection of the data), and documentation is entered by a person (for example, keywords used to describe the data).

Label class

Label classes can be used to restrict labels to certain features or to specify different label fields, symbols, scale ranges, label priorities, and sets of label placement options for different groups of labels.

Attribute

Nonspatial information about a geographic feature in a GIS, usually stored in a table and linked to the feature by a unique identifier. For example, attributes of a river might include its name, length, and sediment load at a gauging station. Attribute tables also store information about feature geometry, such as length and area.

Vertex (vertices)

One of a set of ordered x,y coordinate pairs that defines the shape of a line or polygon feature.

Model

One process or a sequence of connected processes in Modelbuilder.

Hillshade

Shadows drawn on a map to simulate the effect of the sun's rays over the varied terrain of the land.

Dynamic text

Text placed on a layout that changes based on the current properties of an element, such as a user name, the date of a project, the file path of the project, the metadata of a map on your page, and so on.

Data type

The attribute of a variable, field, or column in a table that determines the kind of data it can store. Common varieties include character, integer, decimal, single, double, and string.

Aspect

The compass direction that a topographic slope faces, usually measured in degrees from north. The aspect can be generated from continuous elevation surfaces.

Legend

The description of the types of features included in a map, usually displayed in the map layout. Legends often used graphics of symbols or examples of features from the map with a written description of what each symbol or graphic represents.

altitude

The height above the horizon, measured in degrees, from which a light source illuminates a surface. Altitude is used when calculating a hillshade, or for controlling the position of a light source in a scene.

Modelbuilder

The interface used to build and edit geoprocessing models in ArcGIS.

Map extent

The limit of the geographic area shown on a map, usually defied by a rectangle. Ina dynamic map display, the map extent can be changed by zooming and panning.

Intersection

The point where two lines cross in geocoding, most often a street crossing.

Endoints

The points that define the length of a line segment

Manual interval classifcation

The process of sorting or arranging entities into groups or categories; on a map, the process of representing members of a group by the same symbol, usually defined in a legend.

Reclassify

The process of taking input cell values and replacing them with new output cell values. ________ is often used to simplify or change the interpretation of raster data by changing a single value to a new value or grouping ranges of values into a single values -- for example, assigning a value of one (1) to cells that have values of 1 to 50, two (2) to cells that range from 51 to 100, and so on.

Symbology

The set of conventions, rules, or encoding in systems that define how geographic features are represented with symbols on a map. A characteristic of a map feature may influence the size, color, and shape of the symbol used.

Cell

The smallest unit of information in raster data, usually square in shape. In a map or GIS dataset, each cell represents a portion of the earth, such as a square meter or square mile, and usually has an attribute value associated with it, such as soil type or vegetation class.

Operator

The symbolic representation of a process or operation performed against one or more operands in an expression, such as + and >. When evaluated, these symbols return a value as their result. If there are several of these symbolic representations in an expression, they are evaluated in order of their precedence.

Join table

The table in a join operation, often a nonspatial table, that is appended to the target layer's attribute table

Target table

The table to which new attributes are appended. Records in a target table are often referred to as target features.

Map

The visual display of geographic data on paper or a screen

Select

To choose from a number or group of features or records; to create a separate set or subset.

Extrude

To stretch a flat 2D shape vertically to create a 3D object.

Spheroid

When used to represent the earth, a three dimensional shape obtained by rotating an ellipse about its minor axis, either with dimensions that approximate the earth or with a part that approximates the corresponding portion of the geoid.

Dissolve

a geoprocessing command that removes boundaries between adjacent polygons that have the same value for a specified attribute.

Attribute join

appending the fields of one table to those of another through an attribute common to both tables.

Map projection

method by which shapes on a globe are transferred to a flat surface. These generally require a systemic mathematical transformation of the earth's graticule of lines of longitude and latitude onto a plane. Some projections can be visiualized as a transparent globe with a light bulb at its center (although not all projections emanate from the globe's center) casting lines of latitude and longitude onto a sheet of paper. Generally, the paper is either flat and placed tangent to the globe (a planar or azimuthal projection) or formed into a cone or cylinder and placed over the globe (a cylindrical or conical projection). Every one of these distorts distance, area, shape, or direction, or some combination thereof.