PASDA's ArcView Tutorial Glossary

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ARC/INFO

A full-featured geographic information system (GIS) from ESRI. (See also GIS.)

ArcView

Desktop browse and query software from ESRI with an advanced graphical user interface (GUI) and object-oriented scripting language. ArcView is well suited for use in a digital spatial library data discovery application.

Atlas GIS

A commercial PC-based GIS. The software package uses the vector data model and is primarily intended for business applications.

Attributes

The different characteristics within a set of data to be mapped into ArcView.Attributes are defined within a table and displayed on a theme.

Base Map

A map containing geographic features, used for locational reference.

BMP

A Microsoft Windows Bitmap

Buffer

A zone of a specified distance around a selected feature.

Buttons

In ArcView a button, when depressed,carries out a particular function as defined by it's script.

CAD

Computer-aided design. An automated system for the design, drafting, and display of graphically oriented information.

CD-ROM

Compact Disk-Read Only Memory. CD-ROM is an optical media. A CD-ROM 5.25-inch disk can hold about 650 megabytes of information.The ISO 9660 standard defines the format of data held on CD-ROM.

Charts

ArcView's charts offer a powerful business graphics and data visualization capability that is fully integrated into ArcView's geographic environment. You can simply click on features on a view to add them to the chart. ArcView lets you work simultaneously with geographic, tabular and chart representations of your data.

Classification

Grouping attributes or features into specific categories.

Coordinates

A set of numbers that designates location in a given coordinate reference system, such as an x,y in a planar coordinate system or an x,y,z in a three-dimensional coordinate system. A coordinate represents a location on the earth’s surface relative to other locations.

Coordinate System

A reference system for defining points on the earth's surface. A coordinate system can be planar (flat) or nonplanar (spherical). The Cartesian system (x,y) is an example of a planar coordinate system. Latitude and longitude (expressed as angles) is an example of a nonplanar coordinate system. A common coordinate system is used to spatially register geographic data for the same area.

Coverage

A component of the ARC/INFO database structure for organizing and storing geographic features represented as points, lines, or areas. Geographic features stored in a coverage typically reflect the same topic or theme. The coverage supports the georelational model, meaning it maintains the relationship between the geometric (locational) and attribute (descriptive) information of geographic features.

Data Conversion

The translation of data from one format to another. Data conversion occurs when data is transferred from one system to another. ARC/INFO supports data conversion from many geographic data formats such as DLG, TIGER, DXF, and DEM.

Data model

A formal method for describing data and its behavior in an application. At the beginning of application design, a conceptual data model defines the user's view of the data, a view that is subsequently matched to the data model of the software (e.g., ARC/INFO) used in building the application.

In ARC/INFO, the data model is the description of the structures and their behavior for managing geographic information. The ARC/INFO data model uses data in different, but integrated, formats such as vector and tabular.

Data Set

A named collection of logically related data items arranged in a prescribed manner.

Database

A logical collection of interrelated information, managed and stored as a unit, usually on some form of mass-storage system such as magnetic tape or disk. A GIS database includes data about the spatial location and shape of geographic features recorded as points, lines, areas, pixels, grid cells, or tins as well as their attributes.

Database Life Cycle

The process of requirements analysis, specification, design, data entry, data verification, data edit, data maintenance, data discovery, and data delivery through which any data will progress. In the early part of the database life cycle, major concerns are with data definition, populating the database, and design of core applications. Later in the life cycle, concerns focus on data maintenance and meeting the needs of a growing and more diverse user community.

Datum

A set of parameters and control points used to accurately define the three-dimensional shape of the Earth (e.g., as a spheroid). The corresponding datum is the basis for a planar coordinate system. For example, the North American Datum for 1983 (NAD83) is the datum for map projections and coordinates within the United States and throughout North America.

Decimal Degrees

The decimal representation of fractions of degrees.


DEM

Digital Elevation Model

Descriptive Data

Tabular data describing the geographic characteristics of map features. Can include numbers, text, images, and CAD drawings about features. ARC/INFO stores descriptive data in feature attribute tables and in related tables.

Digitize

To employ a digitizing tablet to record x,y or x,y,z values for map features. Lines are traced to define their shape. A digitizer button, pressed periodically along the line, records x,y coordinates. So, a digitized line is a series of x,y coordinates.

Digitizer

A device that consists of a table and a cursor with crosshairs and keys used to record the locations of map features as x,y coordinates.

DOQ

Digital Orthophoto Quadrangle

Download

To transfer a file or program from a central computer to a smaller computer or to a computer at a remote location.

DRG

Digital Raster Graphic

Enterprise-wide GIS

A Geographic Information System that is integrated with other information technologies, distributes processing between organizational client and server computers, and provides on-line access to organizational databases.

ESRI

Environmental Systems Research Institute (company, Redlands, California)

Executive Information System (EIS)

An information system specifically taylored to meet executive level decision support requirements.


Features

Each theme within ArcView GIS contains a set of spatially defined characters, shapes, or areas called features, each is defined by the attributes or charactersitics it represents. A theme can display all features with a specific attribute or a feature selection within it.

FGDC

The United States Federal Geographic Data Committee. Composed of representatives of several federal agencies, the FGDC has the lead role in defining spatial metadata standards, which it describes in the Content Standards for Spatial Metadata (CSSM).

File

A set of related information that a computer can access by a unique name (e.g., a text file, a data file, a DLG file). Files are the logical units managed on disk by the computer’s operating system. Files may be stored on tapes or disks.

format

The pattern into which data are systematically arranged for use on a computer. A file format is the specific design of how information is organized in the file. For example, ArcView has specific, proprietary formats used to store coverages.

FTP

File Transfer Protocol

Geocode

The process of identifying a location by one or more x,y coordinates from another location description such as an address. For example, an address can be matched against a TIGER street network to determine the location of a home.

Geographic Data

The locations and descriptions of geographic features. The composite of spatial data and descriptive data.

Geographic Database

A collection of spatial data and related descriptive data organized for efficient storage and retrieval by many users.

Geographic Feature

A discrete geographic phenomenon such as a lake, city or building. ARC/INFO represents features in coverages with its vector data model. Abstract entities such as item footprints are also geographic features.

Geo-reference

To establish the relationship of one data set to another through reference to common locations in both data sets. For example, a satellite image can be georeferenced to data stored in a coverage. Georeferencing requires that data be placed in a common coordinate system.

GIF

Graphics Interchange Format

GIS

Geographic information system. An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information. Complex spatial analysis and geographic data processing is possible with a GIS that would be difficult, time-consuming, or impracticable otherwise.

GPS

Global positioning system. A system of geostationary satellites, ground receivers, and associated software that provides an electronically instrumented means of determining position on the earth.

GUI (Graphical User Interface)

A user interface based on graphics (icons and pictures and menus) instead of text; uses a mouse as well as a keyboard as an input device.

Hardware

The physical components of a computer system - the computer, plotters, printers, terminals, digitizers, and so on.

Hydraulic Conductivity

A measure of the rate that water passes through various soils. Values are usually expressed in meters per second.

Idrisi

A pc-based GIS developed by Clark University. The software packages uses the gridded data model and is primarily intended for educational applications.

Import

A function which changes the format of a file to be compatable with the desired application.

INFO

A tabular DBMS used by ARC/INFO to store and manipulate feature attribute and related tables.

Interface

A hardware and software link that connects two computer systems, or a computer and its peripherals, for data communication.

Internet

An international consortium of wide area networks that operate using a standard set of addresses, allowing machine-to-machine connectivity on a global scale. The Internet is an outgrowth of a Defense Advanced Research Projects Agency (DARPA) research project in the early 1970s to provide connectivity between scientists running computer simulations in different locations. Additional regional, private, and public networks have joined the Internet over time. At this point there are over one million computers that now have direct access to the resources on the Internet.

JPEG

Joint Photographics Experts Group

Layer

A logical set of thematic data described and stored in a map library. Layers organize a map library by subject matter (e.g., soils, roads, and wells), and extend over the entire geographic area defined by the spatial index of the map library.

Layouts

In ArcView layouts you create high quality, full color maps by first arranging the various graphic elements on-screen the way you want them. They have a live link to the data they represent, and any changes to the data are automatically included.

Legend

An explanatory table or list of the symbols appearing on a map or chart. In ArcView a legend defines which features of a theme are displayed in the view map.

Magnetic Disk

A storage medium consisting of a spinning disk coated with a magnetic material for recording digital information

Map

An abstract representation of the physical features of a portion of the Earth's surface graphically displayed on a planar surface. Maps display signs, symbols, and spatial relationships among the features. They typically emphasize, generalize, and omit certain features from the display to meet design objectives.

Map Info

A commercial PC-based GIS. The software package uses the vector data model and is primarily intended for business applications.

Map Projection

A systematic conversion of locations on the Earth’s surface from spherical to planar coordinates. Because the earth is three-dimensional, some method must be used to depict a map in to dimensions. A mathematical model that transforms the locations of features on the Earth’s surface to locations on a two-dimensional surface. Some projections preserve shape; others preserve accuracy of area, distance, or direction. (See also coordinate system.)

Megabyte

A measure of data size. One megabyte (MB) equals 1024 kilobytes.

Metadata

Metadata is information about the content, quality, condition, and other characteristics of information kept in a database. metadata is software accessible, and therefore is vital in the development of advanced database systems, such as a digital spatial library.

MPEG

Moving Pictures Experts Group

Mylar

A clear, plastic material used for mapping. Mylar maps are frequently overlayed on paper basemaps to combine information.

NED

National Elevation Database

Network

1. An interconnected set of arcs representing possible paths for the movement of resources from one location to another.

2. A coverage representing linear features containing arcs or a route-system.

3. When referring to computer hardware systems, a local area network or a wide area network.

Normalizing

Re-classifying a set of attribute categories based on a third variable.

Overlay

A dataset, in image format, that can be placed over others.

Peripheral Device

A hardware device not part of the central computer. Examples are digitizers, plotters, and printers.

Project

A project is the file in which your ArcView work is stored. A project typically contains all the view, tables, charts, layouts and scripts that you use for a particular ArcView application. These are the components of a project. Project files have an .apr extension.

Project Window

Every ArcView project has a project window that you use to manage the views, tables, charts, layouts, scripts, and other components in the project. It has a scrolling list of icons on its left side that you use to choose the component you want to display or to create a component of a particular type; each icon represents a document user interface.

Promote

In ArcView, promoting will move a selection on in a table to the top of the table.

Quadrangle

A four-sided figure, bounded by parallels of latitude and meridians of longitude, used as an area unit in mapping. A well-known map series is the USGS 7.5-minute topographic quadrangle. Each map in this map series covers 7.5 degrees of latitude and longitude and provides basic earth information such as elevation, hydrography, vegetation, and cultural features such as roads and buildings.

Raster

A cellular data structure composed of rows and columns. Groups of cells represent features. The value of each cell represents the value of the feature. Image data is stored using this structure.

RDBMS

Relational database management system. A database management system with the ability to access data organized in tabular files that can be related to each other by a common field (item). An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage.

Relational Database

A method of structuring data as collections of tables that are logically associated to each other by shared attributes. Any data element can be found in a relation by knowing the name of the table, the attribute (column) name, and the value of the primary key.

Remote Sensing

Acquiring information about an object without contacting it physically. Methods include aerial photography, radar, and satellite imaging.

Scale

The extent of reduction needed to display a representation of the earth's surface on a map. A statement of a measure on the map and the equivalent measure on the earth’s surface, often expressed as a representative fraction of distance, such as 1:24,000 (one unit of distance on the map represents 24,000 of the same units of distance on the earth). Map scale can also be expressed as a statement of equivalence using different units; for example, 1 inch = 1 mile or 1 inch = 2,000 feet.

Scale can be used as a measure of viewable detail; small scale implies less detail is visible, large scale implies more detail is visible. Thus, scale can be used to control display; as scale increases (becomes larger and more “zoomed in”) more detail can be displayed without overcrowding the screen display.

Scanning

The process of data input in a raster format with a device called a scanner. Some scanners also use software to convert raster data to vector data.

Scripts

ArcView scripts are macros written in Avenue, ArcView's programming language and development environment. With Avenue you can customize almost every aspect of ArcView, from adding a new button to run a script you write, to creating an entire custom application that you can distribute.

Spatial Analysis

The process of modeling, examining, and interpreting model results. Spatial analysis is the process of extracting or creating new information about a set of geographic features. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding.

Spatial Data

Information about the location and shape of, and relationships among, geographic features, usually stored as coordinates and topology.

Spatial Modeling

Analytical procedures applied with a GIS. There are three categories of spatial modeling functions that can be applied to geographic data objects within a GIS: (1) geometric models, such as calculating the Euclidean distance between objects, generating buffers, calculating areas and perimeters, and so on; (2) coincidence models, such as polygon overlay; and (3) adjacency models (pathfinding, redistricting, and allocation). All three model categories support operations on geographic data objects such as points, lines, polygons, tins, and grids. Functions are organized in a sequence of steps to derive the desired information for analysis.

State Plane Coordinate System

The State Plane Coordinate System is not a map projection. It is a coordinate system that divides all fifty of the U.S. states into over 120 numbered sections. The system was designed to provide a common reference system to mappers.

SQL

Structured Query Language. A syntax for defining and manipulating data from a relational database. Developed by IBM in the 1970s, it has become an industry standard for query languages in most relational database management systems.

System Design

The methodology of creating a computer system that takes into account such factors as user needs, performance levels, database design, hardware specifications, and data management.

System 9

An early 1980’s vector based GIS designed for prime computers.

Table of Contents

An explanatory table or list of the symbols appearing on a map or chart. In ArcView a legend defines which features of a theme are displayed in the view map.

Tabular Data

Data stored in a format of records and columns (e.g., as a table). Tabular data are commonly numeric or text data. DBMS technology is used to manage tabular data. Part of the ARC/INFO data model is tabular data that represent the attributes of geographic features.

Terminal

A device, usually a display monitor and a keyboard, used to communicate with the computer.

Theme

Used in ArcView; a collection of geographic objects defined by the user. Examples of themes in digital libraries include footprints, background cartography, and place names.

Tools

In ArcView a tool changes the mouse control from it's original graphic (usually and arrow) to a new one which performs a specific function.

Topographic Map

1. A map containing contours indicating lines of equal surface elevation (relief), often referred to as topo maps.

2. Often used to refer to a map sheet published by the U.S. Geological Survey in the 7.5-minute quadrangle series or the 15-minute quadrangle series.

Topology

The spatial relationships between connecting or adjacent coverage features (e.g., arcs, nodes, polygons, and points). For example, the topology of an arc includes its from- and to-nodes, and its left and right polygons. Topological relationships are built from simple elements into complex elements: points (simplest elements), arcs (set of connected points), areas (sets of connected arcs), and routes (sets of sections, which are arcs or portions of arcs). Redundant data (coordinates) are eliminated because an arc may represent a linear feature, part of the boundary of an area feature, or both. Topology is useful in GIS because many spatial modeling operations don't require coordinates, only topological information. For example, to find an optimal path between two points requires a list of the arcs that connect to each other and the cost to traverse each arc in each direction. Coordinates are only needed for drawing the path after it is calculated.

Universal Transverse Mercator (UTM)

A mathematical transformation of he earth's surface to create a flat map sheet. The UTM projection is well suited for small areas.



Unzip/Zip

To create a compressed archive(a "zip file") from one or more files using PKware's PKzip or a compatible archiver. Its use is spreading from MS-DOS now that portable implementations of the algorithm have been written.

USGS

United States Geological Survey.

Vadose Zone

The upper most zone within the ground that contains a fluctuating amount of moisture.

Vector

A coordinate-based spatial data structure commonly used to represent geographic features. For example, a linear feature is represented as an ordered list of x,y coordinates.

View

A view is an interactive map that lets you display, explore, query and analyze geographic data in ArcView. A view defines the geographic data that will be used and how it will be displayed; it doesn't contain the geographic data but references and reflects the current status of the source data.

Window

A small area on a screen in which a file or a application can be displayed. Windows are resizable, and multiple files can be displayed simultaneously.

World Wide Web (WWW)

Developed by the CERN consortium in Switzerland as a distributed hypermedia server. It allows one to prepare electronic documents that are composites of, or pointers to, many different files of potentially different types, scattered across the world. It employs a hypertext markup language (shtml) to create the documents it serves and to follow “links” known as Universal Resource Locators (URLs) to fetch the document from elsewhere on the Internet. A WWW server does not provide search capabilities, rather it provides explicit linkage between files on the Internet using hypertext. This allows one to organize information in a particular way, but, unless the links exist, does not permit the discovery of other information that was not associated by the author. WWW can be accessed by Mosaic.