GIS Glossary
| Term | Category | Description |
|---|---|---|
| Aerial Image | type of image, data or file format | Low altitude image of the earth, usually taken from a plane or drone. |
| ArcGIS | software or other technology used in mapping | Popular GIS software suite from Esri, used worldwide. |
| ArcGIS Desktop | software or other technology used in mapping | Popular GIS desktop software from the ArcGIS suite. Superseded by ArcGIS Pro. |
| ArcGIS Enterprise | software or other technology used in mapping | Server-based GIS solution from Esri. |
| ArcGIS Online | software or other technology used in mapping | Cloud-based GIS Solution from Esri. Can be used with ArcGIS Enterprise. |
| ArcGIS Pro | software or other technology used in mapping | Popular GIS desktop software from the ArcGIS suite. |
| Attribute | terminology | Information appended in tabular format to spatial features. |
| Band | terminology | A raster dataset contains one or more layers called bands. For example, a colour image has three bands (red, green, and blue) while a DEM has one band (holding elevation values). |
| Basemap | terminology | An underlying map (usually raster) that provides a background of geographical context for the content you want to display. |
| Bathymetry | terminology | Underwater depth of ocean floors or lake floors, often depicted by tinted bands of colour. |
| British National Grid | projection or coordinate system | The Ordnance Survey National Grid reference system. Read more... |
| Buffer | terminology | Common GIS geoprocessing task to create a buffer around input features to a specified distance. |
| Cadcorp | software or other technology used in mapping | British-based software development company focused on GIS and web mapping software. |
| Central Meridian | terminology | Centreline of longitude for map projections. |
| Clip | terminology | Common GIS geoprocessing task to cut one layer by another. |
| Computer-Aided Design (CAD) | software or other technology used in mapping | Software to aid in the creation of technical designs and plans, not specifically geographic. |
| Contour | terminology | Lines on a map joining points of equal elevation. Contour lines very close together indicate a steep slope and contours further apart show a gentle slope. |
| Coordinate | terminology | A group of numbers used to indicate the position of a point either 2-dimensionally or 3-dimensionally. |
| Coordinate System | terminology | A geographic coordinate system (GCS) uses a three-dimensional spherical surface to define locations on the earth. |
| Dangle Node | terminology | Unconnected node of a dangling line. |
| Datum | terminology | A datum is built on top of a selected spheroid and can incorporate local variations in elevation. A datum is used with a Geographic Coordinate System (GCS) |
| Digital Elevation Model (DEM) | type of image, data or file format | A GIS grid or raster representing elevation. |
| Digital Surface Model (DSM) | type of image, data or file format | A 3-dimensional model representing surface elevation, which captures both the natural and artificial features of the environment such as buildings and tree canopies. |
| Digital Terrain Model (DTM) | type of image, data or file format | A 3-dimensional model representing ground elevation. |
| Digitise | terminology | The process of converting geographic data either from a hardcopy or a scanned image into vector data by tracing the features. |
| Dissolve | terminology | Common GIS geoprocessing task that aggregates features based on specified attributes. |
| Edge Match | terminology | A procedure to adjust the position of features extending across map sheet boundaries. |
| Elevation | terminology | Height above a given level, such as mean sea level. |
| Envelope | terminology | A rectangular area with a spatial reference that is defined by the extent of a feature or group of features. |
| Esri | software or other technology used in mapping | Popular GIS software vendor |
| EuroGlobalMap | map data provider or data set | A 1:1 million scale topographic dataset covering 55 countries and territories in the European region. OpenData from EuroGeographics. |
| Feature Class | terminology | Homogeneous collections of common features in ArcGIS, each having the same spatial representation, such as points, lines, or polygons, and a common set of attribute columns. |
| Gazetteer | terminology | A geographical index. |
| GEBCO | map data provider or data set | The General Bathymetric Chart of the Oceans (GEBCO) is a set of OpenData bathymetry data sets. Read more... |
| Generalisation | terminology | Common GIS geoprocessing task to reduce detail in data. |
| Geocode | terminology | Common GIS task to take a text-based description of a location, such as an address or the name of a place, and return geographic coordinates. |
| Geodatabase | type of image, data or file format | The primary data storage model for ArcGIS software products and services. |
| Geographic Coordinate System (GCS) | terminology | A geographic coordinate system (GCS) defines a three-dimensional spherical surface and coordinate system to define locations on the earth. |
| Geographic Transformation | terminology | A geographic transformation is a mathematical operation that converts the coordinates from one geographic coordinate system to another. |
| Geography Markup Language (GML) | type of image, data or file format | The XML grammar defined by the Open Geospatial Consortium (OGC) to express geographical features. |
| GeoJSON | type of image, data or file format | An popular text-based open standard GIS format. |
| Geometry | terminology | A vector feature has its shape represented using geometry. The geometry is made up of one or more interconnected vertices. |
| GeoNames | map data provider or data set | The GeoNames geographical database covers all countries and contains over eleven million place names that are available for download free of charge. Read more... |
| GeoPackage (GPKG) | terminology | An open, non-proprietary, platform-independent and standards-based data format for GIS. |
| Geoprocessing | terminology | Geoprocessing is a framework and set of tools for processing geographic and related data. |
| Georeferencing | terminology | Georeferencing is the process of taking a raster image and adding geographic information to the image so that GIS software can 'place' the image in its appropriate real world location. |
| GeoServer | software or other technology used in mapping | GeoServer is an open source server for sharing geospatial data. |
| GeoTIFF | type of image, data or file format | A TIFF image with embedded georeferencing information. |
| GIS | terminology | A geographic information system (GIS) is a framework for gathering, managing, and analysing spatial data. Read more... |
| GPS | type of image, data or file format | Satellite-based radionavigation system owned by the United States government. Read more... |
| GPX | type of image, data or file format | An XML schema designed as a common GPS data format for software applications. Read more... |
| GRASS | software or other technology used in mapping | Open source GIS software suite. QGIS can be used as a user-friendly graphical interface to GRASS. |
| Hillshading | type of image, data or file format | Hillshading is a technique for creating relief maps, showing the topographical shape of hills and mountains using shading. Hillshading can be created by hand or from DEMs. |
| Hypsometric Tints | terminology | Colours placed between contour lines to indicate elevation. |
| Intersect | terminology | Common GIS geoprocessing task that computes a geometric intersection of the input features. |
| KML/KMZ | type of image, data or file format | Keyhole Markup Language (KML) is a file format used to display geographic data in an Earth browser such as Google Earth. A KMZ file consists of a main KML file and zero or more supporting files that are packaged using a Zip utility into one unit. |
| Lambert Azimuthal Equal Area | projection or coordinate system | Equal-area map projection named after the Swiss mathematician Johann Heinrich Lambert. The projection preserves areas and is widely used in GIS when representing distribution or density. |
| Lambert Conformal Conic | projection or coordinate system | Conformal conic map projection named after the Swiss mathematician Johann Heinrich Lambert. The projection preserves angles locally and is popular in cartography. |
| Landsat | type of image, data or file format | Freely available satellite imagery and remote sensing data at a resolution of 30 metres. |
| Latitude | terminology | A geographic coordinate that specifies the north–south position of a point on the Earth's surface. |
| Layer | terminology | GIS software displays maps and data in layers, drawn in a particular order. |
| Leaflet | software or other technology used in mapping | An open-source JavaScript library for mobile-friendly interactive maps. Read more... |
| LiDAR | type of image, data or file format | An acronym for "light detection and ranging". It is a method of creating accurate 3D models of the Earth’s surface using lasers, usually mounted in aircraft or drones. Lidar is particular useful in surveying, assesing flood risk and archaeology. Read more... |
| Longitude | terminology | A geographic coordinate of a point on the Earth's surface measured east or west of the prime meridian. |
| Map Projection | terminology | A mathematical procedure used to represent the 3-dimensional surface of the earth on a 2-dimensional plane such as a paper map or screen. |
| MapInfo | software or other technology used in mapping | Popular GIS software suite from Pitney Bowes, used worldwide. |
| Maplex Label Engine | software or other technology used in mapping | An ArcGIS extension used for placing map labels automatically. |
| MapServer | software or other technology used in mapping | MapServer is an open source platform for publishing spatial data and interactive mapping applications to the web. |
| MasterMap | type of image, data or file format | The OS MasterMap is the premier digital product of the Ordnance Survey. |
| Mercator | software or other technology used in mapping | A cylindrical map projection widely used for navigation charts and interactive maps. Read more... |
| Meridian | terminology | The half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. |
| Metadata | type of image, data or file format | Information about data such as coverage, format, accuracy, rights and contact information. Read more... |
| MySQL | database for storing map data | MySQL is an open-source RDBMS. |
| NASA | map data provider or data set | The US space agency that allows free access to satellite imagery and DEMs. |
| NaturalEarth | map data provider or data set | Public domain worldwide dataset available at 1:10m, 1:50m, and 1:110 million scales. |
| NetCDF | type of image, data or file format | NetCDF (network Common Data Form) is a file format for storing scientific multidimensional datasets, such as geographic data based on time. |
| Network | terminology | Interconnect set of lines representing routes upon which people, goods, etc. can travel. |
| Node | terminology | Points that connect lines in a network. |
| OpenCycleMap | map data provider or data set | An OpenStreetMap rendering layer like the standard tile layer, but primarily aimed at showing information useful to cyclists. |
| OpenData | type of image, data or file format | Data that anyone can access, use and share. |
| OpenLayers | type of image, data or file format | OpenLayers is an open-source JavaScript library for displaying map data in interactive maps. Read more... |
| OpenSeaMap | map data provider or data set | A software project collecting freely usable nautical information and geospatial data to create a worldwide nautical chart. |
| OpenStreetMap (OSM) | map data provider or data set | A collaborative project to create a free editable map of the world. Read more... |
| Ordnance Survey (OS) | map data provider or data set | The national mapping agency for Great Britain. Read more... |
| OSGB 1936 | projection or coordinate system | The datum used by the Ordnance Survey. |
| OSNI | map data provider or data set | The official producer of geographic mapping data for Northern Ireland. |
| Polygon | terminology | A GIS object that stores geographic coordinates that enclose an area. |
| PostGIS | database for storing map data | Spatial extension for PostgreSQL. |
| PostgreSQL | database for storing map data | An open source RDBMS also known as Postgres. |
| Python | software or other technology used in mapping | A programming language often used in GIS. |
| QGIS | software or other technology used in mapping | A popular open source GIS. |
| Raster | type of image, data or file format | A raster image is an image file format that's defined by a pixel with one or more numbers associated with it. |
| Rasterise | terminology | The process of converting vector data to raster data. |
| Relational Database Management System (RDBMS) | database for storing map data | Software used for managing relational databases, such as Oracle, SQL Server, MySQL and PostgreSQL. |
| Remote Sensing | terminology | The science of obtaining information about objects or areas from a distance, typically using drones, aircraft or satellites. The technology samples emitted and reflected electromagnetic (EM) radiation from the Earth in order to detect and monitor the physical characteristics of an area such as the condition of vegetation. |
| Robinson | projection or coordinate system | A popular map projection that is a compromise between equal-area and conformal that produces a good quality overall view of the world. |
| Rubber sheeting | terminology | A GIS process used to align two or more layers. This process moves the features of a layer using a piecewise transformation that preserves straight lines. |
| Satellite image | type of image, data or file format | Images of Earth collected by imaging satellites |
| Scale | terminology | The scale of a map is the ratio of a distance on a map to the corresponding distance on the ground. Small scale maps generally show less detail than large scale maps, but cover large parts of the Earth. |
| Self-intersection | terminology | Part of a polygon which twists around such that it intersects itself, causing a loop. |
| Shapefile | type of image, data or file format | Popular open GIS vector format developed by Esri. |
| Sliver Polygon | terminology | A sliver polygon is a small polygon feature commonly occurring along the borders of polygons following a overlay of two or more polygon datasets or as a result of inaccurate digitising. |
| Snapping | terminology | The process of moving a feature to match or coincide exactly with another point or feature's coordinates when your pointer is within a specified distance (tolerance). |
| Spatial Analysis | terminology | The methods to study the location, distribution, and relationship of spatial phenomena. |
| Spatial Query | terminology | Database query that makes use of objects defined in a geometric space. |
| Spheroid | terminology | Definition of the shape of the Earth based on an ellipse using two radii. |
| Spheroid | terminology | A spheroid is a three-dimensional shape created from a two-dimensional ellipse and is used within a datum. |
| SQL | software or other technology used in mapping | Language used in programming and designed for managing data held in an RDBMS |
| SRTM | type of image, data or file format | The Shuttle Radar Topography Mission (SRTM) was a research effort that obtained DEMs on a near-global scale using the space shuttle. Read more... |
| Topology | terminology | A set of rules and behaviors that model how GIS points, lines, and polygons share coincident geometry. |
| Transverse Mercator | projection or coordinate system | Popular map projection that is an adaptation of the standard Mercator projection. It is widely used in national and international mapping systems. |
| USGS | map data provider or data set | The United States Geological Survey (USGS) are a primary source of GIS data. |
| UTM | projection or coordinate system | A global coordinate system using zones based on Transverse Mercator. |
| Van der Grinten | projection or coordinate system | Compromise map projection used in Maps International world maps. |
| Vector | terminology | Vector data is used to represent real world features in a GIS. A vector feature can have a geometry type of point, line or a polygon. Each vector feature has attribute data associated with it. |
| Vertex/Vertices | terminology | Vertices (singular Vertex) are used to define the shape and location of line and polygon feature representations. |
| Web Map Service (WMS) | type of image, data or file format | Web Map Service (WMS) is a standard developed by the Open Geospatial Consortium (OGC) for serving georeferenced map images online. |
| Web Feature Service (WFS) | type of image, data or file format | Web Feature Service (WMS) is a standard developed by the Open Geospatial Consortium (OGC) for serving geographical features as vector data online. |
| Web Coverage Service (WCS) | type of image, data or file format | Web Coverage Service (WCS) is a standard developed by the Open Geospatial Consortium (OGC) for serving geographical coverge data online - raw data that can be multidimensional, for instance incuding temporal information. |
| Web Map Tile Service (WMTS) | type of image, data or file format | Web Map Tile Service (WMTS) is a standard developed by the Open Geospatial Consortium (OGC) for serving pre-rendered map tiles online. |
| WGS 1984 | projection or coordinate system | A popular geodetic datum used by the United States and GPS. |