Managing Records: Electronic Records: Managing GIS Records: GIS Development Guides
GIS Development Guides
GIS Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Accuracy - Degree of conformity with a standard, or the degree of correctness attained in a measurement. Accuracy relates to the quality of a result. If accuracy is relative, the position of a point is defined in relation to another point. It is less expensive to build a GIS in the context of relative accuracy. If accuracy is absolute, the position of a point is defined by a coordinate system. Building a GIS in the context of absolute accuracy requires use of the global positioning system.
Accuracy Requirement - statement of how precise the desired results must be to support a particular application.
Adjoining Sheets - Maps that are adjacent to one another at the corners and on one or more sides.
Aerial - Relating to the air atmosphere, being applicable in a descriptive sense to anything in space above the ground and within the atmosphere.
Aerial Photography - The method of taking photographs from an aerial platform (aircraft). 1. Vertical photography, some times called orthophotography, is used for photogrammetric mapping and requires a high degree of accuracy. 2. Oblique photography is used for general information, sometimes to verify certain attributes, but does not provide accurate measurements for photogrammetric mapping.
Aerial Survey - A survey utilizing aerial photography or from remote sensing technology using other bands of the electromagnetic spectrum such as infrared, gamma or ultraviolet.
Algorithm - A set of instructions; ordered mathematical steps for solving a problem like the instructions in a computer program.
Alignment - Relates to survey data transposed to maps. The correct position of a line or feature in relation to other lines or features. Also the correct placement of points along a straight line.
Alphanumeric - A combination of alphabetic letters, numbers and or special characters. A mailing address is an alphanumeric listing.
Analog Data - Data represented in a continuous form, not readable by a computer.
Area - Level of spatial measurement referring to a two-dimensional defined space; for example, a polygon on the earth as projected onto a horizontal plane.
Attribute - 1. A numeric, text, or image data field in a relational data base table that describes a spatial feature such as a point, line, node, area or cell. 2. A characteristic of a geographic feature described by numbers or characters, typically stored in tabular format, and linked to the feature by an identifier. For example, attributes of a well (represented by a point) might include depth, pump type, location, and gallons per minute.
AM/FM - Automated mapping/facilities management. A GIS designed primarily for engineering and utility purposes, AM/FM is a system that manages databases related to spatially distributed facilities.
Base Data - Set of information that provides a baseline orientation for another layer of primary focus, e.g., roads, streams, and other data typically found on USGS topographic and/or planimetric maps.
Base Line - A surveyed line established with more than usual care upon which surveys are based.
Base Map - A map showing planimetric, topographic, geological, political, and/or cadastral information that may appear in many different types of maps. The base map information is drawn with other types of changing thematic information. Base map information may be as simple as major political boundaries, major hydrographic data, or major roads. The changing thematic information may be bus routes, population distribution, or caribou migration routes.
Base Station - A GPS receiver on a known location that may broadcast and/or collect correction information for GPS receivers on unknown locations.
Bench Mark - A relatively permanent point whose elevation above or below an adopted datum is known.
Beta Test - Hardware or software testing performed by users in a normal operating environment; follows alpha testing, which is generally done in the developer's facility.
Bezier - (computer graphics) A curve generated by a mathematical formula in CAD programs that maintains continuity with other Bezier curves.
Binary - The fundamental principal behind digital computers. Binary means two, computer input is converted into binary numbers made up of O and 1 (see bit).
BIT - (computers) A binary digit with a value of either 1 or 0.
Block (Tax) - A group of municipal tax lots that can be isolated from other parcels by a boundary, usually a roadway, waterway or properly labeled lot line.
Boundary Line - A line along which two areas meet. In specific cases, the word "boundary" is sometimes omitted, as in "state line", sometimes the word "line" is omitted, as in "international boundary", "county boundary", etc. The term "boundary line" is usually applied to boundaries between political territories, as "state boundary line", between two states. A boundary line between privately owned parcels of land is termed a property line by preference, or if a line of the United States public land surveys, is given the particular designation of that survey system, as section line, township line, etc.
BPS - Bits per second, the speed of data transfer.
Buffer - A zone of a given distance around a physical entity such as a point, line, or polygon.
CAD/CADD - (computers) Computer-Aided Design/ Computer-Aided Design and Drafting. Any system for Computer-Aided rather than manual drafting and design. Displays data spatially. on a predefined coordinate grid system, allowing data from different sources to be connected and referenced by location. Speeds conventional map development process by 1. permitting replication of shapes, floor plans, etc. from an electric library rather than requiring every component to be drawn from scratch. 2. Plotters and terminal screens are faster and more accurate than manual drafting. 3. Portions of drawings can be edited, enlarged, etc. quickly. 4. Related information can be stored in files and added to drawings in layers.
CAD - (communication) Computer-Aided Dispatching. Used with emergency vehicles, CAD can be very sophisticated. Online maps of a city can display emergency vehicles as moving dots on the map, their status (enroute to an emergency, awaiting a call, call completed, returning to base, etc.) indicated by different colors. (The acronym for computer-aided dispatch is sometimes confused with computer-aided design.)
Cadastre - A record of interests in land, encompassing both the nature and extent of interests. Generally, this means maps and other descriptions of land parcels as well as the identification of who owns certain legal rights to the land (such as ownership, liens, easements, mortgages, and other legal interests). Cadastral information often includes other descriptive information about land parcels.
Cadastral - Relating to the value, extent and ownership of land for tax purposes. Cadastral maps describe and record ownership. Also called property map.
Cadastral Survey - A survey relating to land boundaries and subdivisions, made to create units suitable for transfer or to define the limitations to title. Derived from "cadastre", and meaning register of the real property of a political subdivision with details of area, ownership, and value. The term cadastral survey is now used to designate the surveys for the identification and resurveys for the restoration of property lines; the term can also be applied properly to corresponding surveys outside the public lands, although such surveys are usually termed land surveys through preference. See also boundary, survey.
Cartographic (Planimetric) Features - Objects like trees or buildings shown on a map or chart.
Cartography - The technology of mapping or charting features of Earth's topography.
Centroid - The "center of gravity" or mathematically exact center of an irregular shaped polygon; often given as an x, y coordinate of a parcel of land.
Clearinghouse - A physical repository structure used to accumulate and disseminate digital data and information concerning that data. In the GIS context a clearinghouse can contain all or a portion of spatial, meta data and informational data.
Client - A software application that works on your behalf to extract some service from a server somewhere on the network. Basic idea, think of your telephone as a client and the telephone company as a server.
COGO - Acronym for Coordinate Geometry achieved via a computer program.
Computer-aided Design or Drafting (CAD) - A group of computer software packages for creating graphic documents.
Control Point - A point in a network, identifiable in data or a photograph, with a given horizontal position and a known surface elevation. It is correlated with data in data set or photograph.
Contour - An imaginary outline of points on the ground which are at the same altitude relative to mean sea level.
Contour Line - A line on a map or chart that connects to points which are at the same elevation.
Contour Map - A map that defines topography (hypsography) by interpreting contour lines as relief.
Control - Also called ground control. A system of survey marks or objects called control points that have established positions and/or elevations verified by ground survey. The marks, or control points, serve as a reference correlating other data such as contour lines determined from aerial surveys.
Conversion - 1. The translation of data from one format to another (e.g., TIGER to DXF; a map to digital files).S 2. Data conversion when transferring data from one system to another (E.g., SUN to IBM).
Coordinate - The position of point is space in respect to a Cartesian coordinate system (x, y and/or z values). In GIS, a coordinate often represents locations on the earth's surface relative to other locations.
Coordinate System - The system used to measure horizontal and vertical distances on a planimetric map. In a GIS, it is the system whose units and characteristics are defined by a map projection. A common coordinate system is used to spatially register geographic data for the same area. See map projection.
CRT - Cathode Ray Tube. A computer screen or monitor.
CTG - Center for Technology in Government
Data Capture - Series of operations required to encode data in a computer-readable digital form (digitizing, scanning, etc.).
Data Dictionary - Description of the information contained in a data base, e.g., format, definition, structure, and usage. It typically describes and defines the data elements of the data base and their interrelationships within the larger context of the data base.
Data Element - Specific item of information appearing in a set of data, e.g. well site locations.
Data Model - 1. A generalized, user-defined view of the data related to applications. 2. A formal method for arranging data to mimic the behavior of the real world entities they represent. Fully developed data models describe data types, integrity rules for the data types, and operations on the data types. Some data models are triangulated irregular networks, images, and georelational or relational models for tabular data.
Data Quality - Refers to the degree of excellence exhibited by the data in relation to the portrayal of the actual phenomena.
Data Sets - A collection of values that all pertain to a single subject.
Data Standardization - The process of achieving agreement on data definitions, representation, and structures to which all data layers and elements in an organization must conform.
Data Structure - Organization of data, particularly the reference linkages among data elements.
Database - Usually a computerized file or series of files of information, maps, diagrams, listings, location records, abstracts, or references on a particular subject or subjects organized by data sets and governed by a scheme of organization. "Hierarchical" and relational" define two popular structural schemes in use in a GIS. For example, a GIS database includes data about the spatial location and shape of geographic entities as well as their attributes.
Database Management System (DBMS) - 1. The software for managing and manipulating the whole GIS including the graphic and tabular data. 2. Often used to describe the software for managing (e.g., input, verify, store, retrieve, query, and manipulate) the tabular information. Many GlSs use a DBMS made by another software vendor, and the GIS interfaces with that software.
Datum - A mathematical reference framework for geodetic coordinates defined by the latitude and longitude of an initial point, the azimuth of a line from this point, and the parameters of the ellipsoid upon which the initial point is located.
DEC - New York State Department of Environmental Conservation
Differential Correction - The method (usually done through post processing) of using two GPS receivers, one on a known location and one on an unknown location, using information from the one on the known location to correct the position of the unknown location.
Digital Accuracy - Refers to the accuracy of digital spatial data capture.
Digital Elevation Model (DEM) - A file with terrain elevations recorded at the intersections of a fine grid and organized by quadrangle to be the digital equivalent of the elevation data on a topographic base map.
Digital Data - A form of representation in which distinct objects, or digits, are used to stand for something in the real world--temperature or time--so that counting and other operations can be performed precisely. Data represented digitally can be manipulated to produce a calculation, a sort, or some other computation. In digital electronic computers, two electrical states correspond to the Is and Os of binary numbers, which are manipulated by computer programs.
Digital Exchange Format (DXF) - 1. ASCII text files defined by Autodesk, Inc. (Sausalito, CA) at first for CAD, now showing up in third-party GIS software . 5 2. An intermediate file format for exchanging data from one software package to another, neither of which has a direct translation for the other but where both can read and convert DXF data files into their format. This often saves time and preserves accuracy of the data by not reautomating the original.
Digital Line Graph (DLG) - 1. In reference to data, the geographic and tabular data files obtained from the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format. 2. In reference to data, the formal standards developed and published by the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format.
Digital Map - A machine-readable representation of a geographic phenomenon stored for display or analysis by a digital computer; contrast with analog map.
Digital Orthophoto - A geographically correct digital image with the same accuracy as a vector digital map, but preserving the information content of the original photography.
Digital Orthophoto Quarter-Quad (DOQ) - A 3.75 minute square distortion free image of the surface of the earth. The imagery has been geographically and photographically rectified to remove all distortion, and meet requirements of the USGS.
Digital Terrain Model (DTM) - A computer graphics software technique for converting point elevation data into a terrain model displaced as a contour map, sometimes as a three-dimensional "hill and valley" grid view of the ground surface.
Digitize - A means of converting or encoding map data that are represented in analog form into digital information of x and y coordinates.
Digitized Terrain Data - Transposed elevation information from maps or photographs to X-Y-Z digital coordinates for storage on magnetic media.
Digitizer - A device used to capture planar coordinate data, usually as x and y coordinates, from existing analog maps for digital use within a computerized program such as a GIS; Also called a digitizing table.
Digitizing - Refers to the process of manually converting an analog image or map or other graphic overlay into numerical format for use by a computer with the use of a digitizing table or tablet and tracing the input data with a cursor (see also scanning).
DIME - Dual Independent Map Encoding Provides vector data such as streets to census data addresses. Superseded by Topologically Integrated Geographic Encoding and Referencing (see TIGER).
DIME File - A geographic base file produced by the U.S. Census Bureau with Dual Independent Map Encoding. Now being superseded by TIGER files.
DLG - See Digital Line Graph.
DOB - New York State Division of the Budget
DOQ - See Digital Orthophoto Quarter-quad.
DOT - New York State Department of Transportation
DTF - New York State Department of Taxation and Finance
Edge Match - An editing procedure to ensure that all features crossing adjacent map sheets have the same edge locations, attribute descriptions, and feature classes.
Federal Information Processing Standards (FIPS) - Official source within the federal government for information processing standards. They were developed by the Institute for Computer Sciences and Technology, at the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards.
Federal Geographic Data Committee (FGDC) - Established by the Federal Office of Management and Budget, is responsible for the coordination of development, use, sharing, and dissemination of surveying, mapping, and related spatial data.
Fifth Generation Computer - A computer designed for applications of artificial intelligence (Al). Some elements of spatial data management, especially the CADD output side, are beginning to integrate Al computing.
FOIL - Freedom of Information Law
Format - 1. The pattern in which data are systematically arranged for use on a computer. 2. A file format is the specific design of how information is organized in the file. For example, DLG, DEM, and TIGER are geographic data sets in particular formats that are available for many parts of the United States.
File Transfer Protocol (FTP) - A standard protocol that defines how to transfer files from one computer to another.
FORTRAN - A high-level programming language and compiler originally designed to express math formulas. Developed in 1954 by IBM it is still the most widely used language for scientific and engineering programming.
GBF/DIME - See Geographic base file/dual independent map encoding .
Geocode - The process of identifying a location as one or more x, y coordinates from another location description such as an address. For example, an address for a student can be matched against a TIGER street network to locate the student's home.
Geodetic Monumentation - A permanent structure that marks the location of a point taking into account the earth's curvature.
Geographic - Pertains to the study of the Earth and the locations of living things, humans and their effects.
Geographic Base File/dual Independent Map Encoding (GBF/DIME) - A data exchange format developed by the US Census Bureau to convey information about block-face/street address ranges related to 1980 census tracts. These files provide a schematic map of a city's streets, address ranges, and geostatistical codes relating to the Census Bureau's tabular statistical data. See also TIGER, created for the 1990 census.
Geographic Database - Efficiently stored and organized spatial data and possibly related descriptive data.
Geographic Information Retrieval and Analysis (GIRAS) - Data files from the US Geological survey. GIRAS files contain information for areas in the continental United States, including attributes for land use, land cover, political units, hydrologic units, census and county subdivisions, federal land ownership, and state land ownership. These data sets are available to the public in both analog and digital form.
Geographic Information System (GIS) - 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. Certain complex spatial operations are possible with a GIS that would be very difficult, time-consuming, or impractical otherwise.
Geographic Object - A user-defined geographic phenomenon that can be modeled or represented using geographic data sets. Examples include streets, sewer lines, manhole covers, accidents, lot lines, and parcels.
Geographical Resource Analysis Support System (GRASS) - 1. A public-domain raster GIS modeling product of the US Army Corps of Engineers Construction Engineering Research Laboratory. 2. A raster data format that can be used as an exchange format between two GlSs.
Georectify - The process of referencing points on an image to the real world coordinates.
Georeference - To establish the relationship between page coordinates on a paper map or manuscript and known real-world coordinates.
Geospatial - A term used to describe a class of data that has a geographic or spatial nature.
Geostationary Satellite - An earth satellite that remains in fixed position in sync with the earth's rotation.
GIS - Geographic information system. A computer system of hardware and software that integrates graphics with databases and allows for display, analysis, and modeling.
Grid-Cell Data - Grid-cell data entry places a uniform grid over a map area, and the area within the cell is labeled with one attribute or characteristic, such as elevation averaged over all points. Grid cells can be layered with differing types of information.
Global Positioning System (GPS) - A system developed by the U.S. Department of Defense based on 24 satellites orbiting the Earth. Inexpensive GPS receivers can accurately determine ones position on the Earth's surface.
Ground Truth - Information collected from a survey area as remote sensing data is being collected from the same area (see control).
Hierarchical - A way of classifying data, starting with the general and going to specific labels.
Hydrography - Topography pertaining to water and drainage feature.
Hypsography - 1 ) The science or art of describing elevations of land surfaces with reference to a datum, usually sea level. 2) That part of topography dealing with relief or elevation of terrain.
Image - A graphic representation or description of an object that is typically produced by an optical or electronic device. Common examples include remotely sensed data such as satellite data, scanned data, and photographs. An image is stored as a raster data set of binary or integer values representing the intensity of reflected light, heat, or another range of values on the electromagnetic spectrum. Remotely sensed images are digital representations of the earth.
Imagery - A two dimensional digital representation of the earth's surface. Examples are a digital aerial photograph, a satellite scene, or an airborne radar scan.
Index - A specialized lookup table or structure within a database and used by an RDBMS or GIS to speed searches for tabular or geographic data.
Infrastructure - The fabric of human improvements to natural settings that permits a community, neighborhood, town, city metropolis, region, state, etc., to function.
Initial Graphics Exchange Specification (IGES) - An interim standard format for exchanging graphics Polygon data among computer systems.
Internet - A system of linked computer networks, worldwide in scope, that facilitates data communication services such as remote login, file transfer, electronic mail, and newsgroups. The Internet is a way of connecting existing computer networks that greatly extends the reach of each participating system.
Internet Protocol (IP) - The most important of the protocols on which the Internet is based. It allows a packet to traverse multiple networks on the way to its final destination.
Interpolate - Applied to logical contouring by determining vertical distances between given spot elevations.
IT - Information Technology
Land Information System (LIS) - The sum of all the elements that systematically make information about land available to users including: the data, products, services, the operating procedures, equipment, software, and people.
Land Information System (LIS) - NJ State 45:8-28(e) - Any computer coded spatial database designed for multi-purpose public use developed from or based on property boundaries.
Latitude - The north-south measurement parallel to the equator.
Layer - A logical set of thematic data, usually organized by subject matter.
Layers - Refers to the various "overlays" of data each of which normally deals with one thematic topic. These overlays are registered to each other by the common coordinate system of the database.
Longitude - The angular distance, measured in degrees, cast or west from the Greenwich meridian, or by the difference in time between two reference meridians on a globe or sphere.
Lot Number - A numerical parcel designation, that when combined with a block number is unique to a single parcel of land within a given municipality.
Manual Digitizing - Conversion of an analog measurement into a digital form by using a manual device such as a calculator.
Map - A representation of a portion of the earth, usually drawn on a flat surface. (From Latin mappa, a napkin, sheet or cloth upon which maps were drawn.)
Map Projection - A mathematical model for converting locations on the earth's surface from spherical to planar coordinates, allowing flat maps to depict three dimensional features. Some map projections preserve the integrity of shape; others preserve accuracy of area, distance, or direction.
Map Units - The coordinate units in which the geographic data are stored, such as inches, feet, or meters or degrees, minutes and seconds.
Metadata - Data describing a GIS database or data set including, but not limited to, a description of a data transfer mediums, format, and contents, source lineage data, and any other applicable data processing algorithms or procedures.
NCGIA - National Center for Geographic Information Analysis
Network Analysis - Addresses relationships between locations on a network. Used to calculate optimal routes, and optimal locations for facilities.
NSGIC - National States Geographic Information Council
NSDI - National Spatial Data Infrastructure
OPRHP - New York State Office of Parks, Recreation and Historical Preservation
ORPS - New York State Office of Real Property Services (formerly Equalization and Assessment)
Orthophoto - A photograph of the earth's surface in which geographic distortion has been removed.
Overlay - A layer of data representing one aspect of related information.
Parcel - Generally refers to a piece of land that can be designated by number.
Photogrammetry - The system of gathering information about physical objects through aerial photography and satellite imagery.
Plane-Coordinate System - A system for determining location in which two groups of straight lines intersect at right angles and have as a point of origin a selected perpendicular intersection.
Planimetric Map - A map which presents the horizontal positions only for the features represented; distinguished from a topographic map by the omission of relief in measurable form. The natural features usually shown on a planimetric map include rivers, lakes and seas; mountains, valleys and plains; and forests, prairies, marshes and deserts. The culture features include cities, farms, transportation routes and public-utility facilities; and political and private boundary lines. A planimetric map intended for special use may present only those features which are essential to the purpose to be served.
Plat - A scale diagram void of cultural, drainage and relief features, showing only land boundaries and subdivisions together with data essential to its legal description.
Plotter - Equipment that can plot a graphic file using multiple line weights and colors. Types available today are: pen, laser, and electrostatic plotters.
Point Data - Level of spatial definition referring to an object that has no dimension, e.g., well or weather station.
Points - Items such as oil wells, utility poles, etc. Specific objects with exact location noted.
Polygon - A vector representation of an enclosed region, described by a sequential list of vertices or mathematical functions.
Positional Accuracy - Term used in evaluating the overall reliability of the positions of cartographic features relative to their true position.
Precision - Refers to the quality of the operation by which the result is obtained, as distinguished from accuracy.
Protocol - A definition for how computers will perform when talking to each other. Protocol definitions range from how bits are placed on a wire to the format of an electronic mail message. Standard protocols allow computers from different manufacturers to communicate; the computers can use completely different software, providing that the programs running on both ends agree on what the data means.
Quadrangle - A four-sided region, usually bounded by a pair of meridians and a pair of parallels.
Quality Control - Process of taking steps to ensure the quality of data or operations is in keeping with standards set for the system.
Raster - A grid-type data format used to interpret gray-scale photographs and satellite imagery. Imagery is stored as dots or pixels, each with a different shade or density.
Raster Data - Machine-readable data that represent values usually stored for maps or images and organized sequentially by rows and columns. Each "cell" must be rectangular but not necessarily square, as with grid data.
RDBMS - See relational database management systems.
Rectified - Referencing points, lines, and/or features of two dimensional images to real world geographic coordinates, to correct distortion in the image.
Rectify - The process by which an image or grid is converted from image coordinates to real-world coordinates. Rectification typically involves rotation and scaling of grid cells, and thus requires resampling of values.
Registration - The procedure used to bring two maps or data layers into concurrence via known ground location control points or the procedure of bringing a map or data layers into concurrence with the earth's surface.
Relational Database Management System (RDBMS) - A database management system with the ability to access data organized in tabular files that may be related together by common field (item). An RDBMS has the capability to recombine the data items from different files, thus providing powerful tools for data usage.
Remote Sensing - Recording imagery or data and information from a distance. Photography is a form of remote sensing. Satellites provide a remote sensing platform for developing geology and soils analysis with sensors sensitive to various bands of the electromagnetic spectrum.
Resolution - 1. The accuracy at which the location and shape of map features can be depicted for a given map scale. For example, at a map scale of 1:63,360 (1 inch=1 mile), it is difficult to represent areas smaller than 1/10 of a mile wide or 1/10 of a mile in length because they are only 1/1 0-inch wide or long on the map. In a larger scale map, there is less reduction, so feature resolution more closely matches real world features. As map scale decreases, resolution also diminishes because feature boundaries must be smoothed, simplified, or not shown at all. 2. The size of the smallest feature that can be represented in a surface. 3. The number of points in x and y in a grid (e.g., the resolution of a USGS one-degree DEM is 1.201 x 1.201 mesh points).
Rubber-sheet - A procedure to adjust the entities of a geographic data set in a non-uniform manner. From- and to- coordinates are used to define the adjustment.
Scale - The relationship between a distance on a map and the corresponding distance on the earth. Often used in the form I :24,000, which means that one unit of measurement on the map equals 24,000 of the same units on the earth's surface.
Scanner - A scanner is an optical device that recognizes dark and light dots on a surface and converts this recognition into a digital file. However, scanners generally do not create a map database in a logically correct format, so additional computer-aided manipulation and often manual editing are used to add intelligence required by a specific GIS platform.
Scanning - Also referred to as automated digitizing or scan digitizing. A process by which information originally in hard copy format (paper print, mylar transparencies, microfilm aperture cards) can be rapidly converted to digital raster form (pixels) using optical readers.
Schematic Map - A map prepared by electronically scanning or digitizing in which the lines are not dimensionally or positionally accurate.
SDTS - Spatial Data Transfer Standard
SED - New York State Education Department
SEMO - New York State Emergency Management Office
Server - Software that allows a computer to offer a service to another computer. Other computers contact the server program by means of matching client software. Also a computer using server software.
Source Material - Data of any type required for the production of mapping, charting, and geodesy products including, but not limited to, ground-control aerial and terrestrial photographs, sketches, maps, and charts; topographic, hydrographic, hypsographic, magnetic, geodetic, oceanographic, and meteorological information; intelligence documents; and written reports pertaining to natural and human-made features.
Spatial Data - Data pertaining to the location of geographical entities together with their spatial dimensions. Spatial data are classified as point, line, area, or surface.
Spatial Index - A means of accelerating the drawing, spatial selection, and entity identification by generating geographic-based indexes. Usually based on an internal sequential numbering system.
Spatial Model - 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 calculation of Euclidian distance between objects, buffer generation area, and perimeter calculation); (2) coincidence models (such as a 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, TlNs, and grids. Functions are organized in a sequence of steps to derive the desired information for analysis.
Stakeholders - Any constituency in the environment that is affected by an organization's decisions and policies.
Standards - In computing, a set of rules or specifications which, taken together, define the architecture of a hardware device, program, or operating system.
State Plane Coordinate System - The plane-rectangular coordinate systems established by the United States Coast and Geodetic Survey (now known as National Ocean Survey), one for each state in the United States, for use in defining positions of geodetic stations in terms of plane-rectangular (X and Y) coordinates. Each state is covered by one or more zones, over each of which is placed a grid imposed upon a conformal map projection. The relationship between the grid and the map projection is established by mathematical analysis. Zones of limited east-west dimension and indefinite north south extent have the transverse Mercator map projection as the base for the state coordinate system, whereas zones for which the above order of magnitude is reversed have the Lambert conformal conic map projection with two standard parallels. For a zone having a width of 158 statute miles, the greatest departure from exact scale (scale error) is 1 part in 10,000. Only adjusted positions on the North American datum of 1927 and NAD 1983 may be properly transformed into plane coordinates on a state system. All such geodetic positions which are determined by the National Ocean Survey are transformed into state plane-rectangular coordinates on the proper grid, and are distributed by that bureau with the geodetic positions. State plane coordinates are extensively used in recording land surveys. and in many states such use has received approval by legislative enactment.
SUNY - State University of New York
System - A group of related or interdependent elements that function as a unit.
Tax Map - An accurate map of a municipal territory prepared for the purpose of taxation. Showing among other things, the location and width of streets, roads, avenues and each individual lot of land within the municipality.
Text Data - Information in a GIS system such as property owners' names and lot dimensions.
Thematic Layer - Mapping categories, consisting of a single type of data such as population, water quality, or timber stands, intended to be used with base data.
Thematic Map - A map that illustrates one subject or topic either quantitatively or qualitatively.
Theme - A collection of logically organized geographic objects defined by the user. Examples include streets, wells, soils, and streams.
TIGER - Supersedes DIME files.
TIGER - See Topologically Integrated Geographic Encoding and Referencing.
Topographic Map - A map of land-source features including drainage lines, roads, landmarks, and usually relief, or elevation.
Topologically Integrated Geographic Encoding and Referencing data (TIGER) - A format used by the US Census Bureau to support census programs and surveys. It is being used for the 1990 census. TIGER files contain street address ranges along lines and census tract/block boundaries. These descriptive data can be used to associate address information and census/demographic data to coverage features.
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 (sets of connected points), areas (sets of connected arcs), and routes (sets of sections) that 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 which arcs connect to each other and the cost of traversing along each arc in each direction. Coordinates are only necessary to draw the path after it is calculated .
Transformation - The process of converting data from one coordinate system to another through translation, rotation, and scaling .
Transmission Control Protocol (TCP) - One of the protocols on which the Internet is based.
Vectors - Lines defined by "x", "y" and "z" coordinate endpoints. Roads, rivers, contour lines, etc. presented as vector lines.
Vector Data - A coordinate-based data structure commonly used to represent map features. Each linear feature is represented as a list of ordered x, y coordinates. Attributes are associated with the feature (as opposed to a raster data structure, which associates attributes with a grid cell). Traditional vector data structures include double-digitized polygons and arc-node models.
Vector Display - A vector display on a computer screen is produced by drawing vectors on the screen. A raster display, in contrast, is produced on a screen as rows of dots of "on" or "off' which produce the picture.
Wide Area Network (WAN) - A network that uses high-speed, long distance communications networks or satellites to connect computers over distances greater than those traversed by local area networks (LANs)--about 2 miles.
Workstations and Terminals - A workstation is a device or a combination of devices integrated to provide the user with graphic data entry, display, and manipulation. These devices are used for map digitizing and map-related applications, geographic analysis and ad hoc query. Most systems still use some type of inexpensive edit-query workstations or terminals to provide low-cost access to both maps and related data.
