Geographic Information Glossary

A
AddressBase®
AddressBase-Premium is the OS vector data set representing addresses and supersedes Address-Point. It provides the most comprehensive view of addresses and properties at all stages of a property and address lifecycle – from planning permission to historic addresses. Both postally addressable objects and OWPA (objects without postal address) are included.
AddressBase-Premium, AddressBase-Plus and AddressBase are OS Licenced Data products.
Address-Point
A legacy dataset. An OS vector data set representing postal address delivery points.
OS support and maintenance for Address-Point is scheduled to end on 31 October 2014.
Address-Point is superseded by AddressBase®
Address-Point is an OS Licenced Data product. - Address-Point Metadata
Annotation
  1. In cartography, text or graphics on a map that provide information for the map reader; it can be used as a singular entity, or plural to refer to several pieces of information. Annotation may identify or describe a specific map entity, provide general information about an area on the map, or supply information about the map itself. In this sense, it could also be referred to as labels or (a) label.
  2. In ArcGIS Annotation is also a specific term, to mean text or graphics that can be individually selected, positioned, and modified. Annotation can be stored a separate file of features that can be added to many maps or as map annotation in one data frame in a specific map.
    Annotation Group
    A container within a map document for organizing and managing text or graphics that provide additional information about features or general areas of a map.
    Annotation Feature Class
    A geodatabase feature class that stores text or graphics that provide information about features or general areas of a map (annotation).
    Annotation class
    A subset of annotation in an annotation feature class that contains properties that determine how the subset of annotation will display.
ArcGIS
The GIS suite of software used by HCC, produced by ESRI.
History
In the past, ArcView 3 and ArcInfo were two separate products. ArcInfo Workstation was a powerful geoprocessing and digitising environment, while ArcView 3 was used to view data and produce maps. ArcInfo and ArcView 3 were combined to produce ArcGIS Desktop, leaving Arcview 3 as a piece of legacy software, which is no longer available. It is however, still used by the majority of staff at HCC. The newest version of ArcView is contained within ArcGIS Desktop (currently version 10).
ArcGIS Desktop
This is the primary application used to compile and author geographic information. It is available at three levels of functionality:
Basic (formerly ArcView)
Provides comprehensive mapping and analysis tools with simple editing and geoprocessing.
Standard (formerly ArcEditor)
Includes advanced editing capabilities for shapefiles and geodatabases in addition to the full functionality of ArcGIS for Desktop Basic.
Advanced (formerly ArcInfo)
the flagship ArcGIS for Desktop product. It builds on the functionality of Standard with advanced geoprocessing. It also includes legacy applications for ArcInfo Workstation.

Within version 9 of the software are three separate sub-applications to Desktop:
ArcMap
This is the main application of ArcGIS and where all of the maps are viewed and created.
ArcCatalog
The interface for managing the data within the GIS system. It is here that new datasets can be created and the tables viewed easily.
ArcToolbox
Links to Geoprocessing Tools used for manipulating the data. The Toolbox can be accessed from either ArcCatalog or ArcMap.

In ArcGIS 10 ArcCatalog and ArcToolbox have been integrated into separate Tabs within the ArcMap interface.
ArcGIS Extensions
Extra applications to add more analysis tools and functionality. For example Crime Analyst used by the Community Safety Team adds specialist tools such as Hotspotting
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B
Boundary-Line
An OS vector data product representing civil administrative boundaries (e.g. County, Parish, Parliamentary Constituency etc.).
Boundary-Line is an OS OpenData product.
Buffer
Zone at a specified distance around features – useful for proximity analysis (e.g. find all postcodes within 500m of a development site).
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C
Centroid
The centroid is the geometric centre of a two dimensional object, being the arithmetic mean of all the points in that object. The centroid of a convex object always lies within that object. However a non-convex object might have a centroid which lies outside that object, perhaps within a neighbouring object. The centroid of a ring lies within the central void. Centroids not contained by the ‘parent’ object can present difficulties when modelling spatial relationships where polygons or lines are represented by their centroids.
Co-ordinate
A method used to describe a location in terms of a series of figures, given in two groups, (x,y) representing the distance from an origin. In cartographic/GIS terminology the ‘x’ co-ordinate is sometimes known as the Easting and the ‘y’ co-ordinate as the Northing.
Copyright
Copyright is a right granted by law that is designed to protect original works; the right to copy is the legal possession of the owner and no one else. Unauthorised copying of copyright material constitutes an illegal act, which may lead to prosecution or civil proceedings. O.S. mapping & digital data is copyright © controlled.
Copyright issues when using maps. (Link Only available to HCC Staff).
Coverage
A coverage was the original file format for ArcInfo when it was a separate entity to ArcView 3, although can still be used in 3 and ArcGIS Desktop. Unlike shapefiles and geodatabase feature classes, coverages can contain more than one type of feature (e.g. points and polygons).
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D
Database
An ordered collection of information managed and stored electronically in tabular form.
Data-Frame
Description Comming Soon
Data-View
Description coming Soon
Digitise
The process of converting analogue data (e.g. data on paper maps) into digital data used in a GIS, by recording x,y co-ordinates for map features.
E
Event Theme
A temporary geographic representation made from a table of features with x, y co-ordinates, before it has been saved as a separate feature class.
Extension
An add-on application that provides additional and specialised tools to ArcView 3 or ArcGIS.
Many of the Extensions within ArcView 3 were written by HCC, and are needed for adding the correct copyright text or viewing photography.
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F
Feature Class
  1. A set of features that has been added to (or exported from) the map. This could refer to a Shapefile, Geodatabase Feature Class, or any Theme/Layer.
  2. A Geodatabase Feature Class.
    This is the main spatial data file format that is used by ArcGIS; it can either be a polygon, line, point or annotation feature class.
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G
Generalisation
Description coming Soon
Geocoding
The process of adding points to a digital map using addresses, postcodes or grid references – the computer equivalent of pushing pins into a wall map.
GIS
Geographic Information System
An organised collection of computer hardware, software, geographic data and personnel, designed to efficiently capture, store, manipulate, analyse and present spatial data.
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I
Icons
Pictorial images appearing on the screen to indicate utility functions, files, folders or applications (programmes).
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L
Label
  1. In cartography, text placed on or near a map feature that describes or identifies it. This is similar to annotation.
  2. In ArcGIS, descriptive text, usually based on one or more feature attributes. Labels are placed dynamically on or near features in a layer. Labels cannot be individually selected and modified by the user.
    Label Class
    In ArcMap, a category of labels that represents features with the same labeling properties. For example, in a schools layer, label classes could be created to define information and style for each type of school: Primary, Secondary or Special could have different colours.
Land-Line
Large scale O.S. vector data, the digital equivalent to the 1/1250 and 1/2500 national grid series maps.
Layer
This is the term used within ArcGIS to refer to any set of features added to the map document. The layer has an associated attribute table and may also have Labels or Annotation. The layer could be a Geodatabase Feature Class, Shapefile, Coverage or Event Theme.
It is not the same thing as a Layer File, although could refer to one.
( In ArcView 3 this was referred to as a Theme)
Layer File
Description coming Soon
Layout
A Layout is the window that provides interactive map layout capabilities in ArcView. Each layout organises a list of graphic objects. It can then draw those objects to the screen, send them to a printer or save them as one of several standard graphics file formats.
Line
A set of ordered co-ordinates representing the shape of geographic features too narrow to be displayed as an area at a given scale (e.g. roads & rivers) or those with no area (e.g. contours).
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M
Map
An abstract representation of the physical features of part of the Earth’s surface graphically displayed on a planar surface.
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N
National Grid
The grid system by which the O.S. references locations relative to a working origin located slightly south-west of the Isles of Scilly. This ensures that all locations on the mainland of Great Britain almost always have positive co-ordinates of less than 1000km. Co-ordinates, or National Grid References (NGRs), are expressed in metres and decimals of a metre according to the precision required.
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O
Ordnance Survey (OS)
The national mapping agency of Great Britain. OS maintain the definitive record of geographic features in Great Britain and create innovative, high quality maps and datasets. Intellectual property rights in OS maps and mapping data is owned by the Crown, © Crown copyright and database rights apply.
See also The Ordnance Survey website .
Ordnance Survey (OS)
OS Licenced data includes the products listed below including 'derived data' created using or in conjunction with OS Licensed Data. Intellectual property rights in OS maps and mapping data is owned by the Crown, © Crown copyright and database rights apply. Users must comply with the terms and conditions of the Public Sector Mapping Agreement Member Licence. See also OS OpenData.
  • OS MasterMap® Topography Layer
  • OS MasterMap® Integrated Transport Network™ (ITN)
    including Road Routing Information (RRI) and Urban Paths Theme
  • OS VectorMap™ Local
  • 1:25000 Scale Colour Raster
  • 1:50000 Scale Colour Raster
  • Code-Point®
  • Code-Point® with polygons
  • AddressBase™, AddressBase™ Plus, AddressBase™ Premium
OS OpenData
Free map data released by OS under the terms of the OS OpenData Licence.
OS retain the IPR and copyright in OS OpenData™ and users must comply with the requirements of the OS OpenData Licence.
See also OS Licenced Data.
OSCAR
A legacy dataset. Ordnance Survey Centre-line Alignment of Roads, a vector dataset.
OSCAR is superseded by OS MasterMap® Integrated Transport Network™ ITN.
OSCAR is an OS Licenced Data product.
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P
Pixel
A contraction of the words ‘picture element’. A single cell within an image such as a scanned map or photograph. Zooming into an image will reveal individual pixels hence image or raster data, as it is known, has a finite resolution.
Point
A single (x,y) co-ordinate that represents a geographic feature too small to be displayed as a line or an area (e.g. a mountain peak or a spot height).
Polygon
A multisided figure (poly = many) that represents an area on the Earth.
Project
In ArcView 3, each separate piece of work is done within a project. A project is a collection of themes, views, and layouts. Only one project is open at a time. The project window in ArcView is like the table of contents for your project. When you save a project you are saving a snapshot of the current state of all the objects that project references. The project file has the extension .apr.
ArcGIS (9, 10) does not work in this way - each layout is stored in a seperate map document with the filepath.mxd
PMSA
Membership of the Public Sector Mapping Agreement gives eligible public sector organisations free access to Ordnance Survey digital map products. The PSMA is a partnership between the Department for Business, Innovation and Skills and Ordnance Survey.
Each PSMA member organisation has a Principal Contact who acts as the main point of contact between that organisation and Ordnance Survey and is the focal point for all general and policy queries relating to the PMSA (including copyright issues), is responsible for placing OS Data orders and for managing Contractors and End-Users Licences.
The Principal Contact for Hertfordshire County Council is Steve Bayley.
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R
Raster Data
A cellular based data structure made up of rows and columns of pixels. Raster images are made up of groups of pixels representing map features. Raster data has no attributes. Ordnance Survey 1:25,000 and 1:50,000 maps are held digitally as raster data. OS VectorMap Local (1:10,000 data) exists in both vector and raster formats.
The Raster Data Model
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S
Shapefile
The default spatial data file format for ArcView3. The data in a shapefile represents some sort of geographical feature or location. Shapefiles are superseded by geodatabase files (.gdb) but are currently still supported by ArcGIS (i.e. ArcMAP10.2).
Strategi
Small scale O.S. vector data, the digital equivalent of their 1/250,000 Travelmaster mapping. Map features in Strategi have been heavily generalised.
Strategi is an OS OpenData product.
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T
Theme
A collection of features or images drawn in a view. A Theme has an associated legend that defines the symbolisation of the features. A theme may have associated graphics; these graphics are visible only when the theme is visible.
(In ArcGIS this is referred to as a Layer.)
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V
Vector Data
A co-ordinate based data structure. Geographic data stored in the form of (x,y) co-ordinates positioning the ends of line segments or points.
The Vector Data Model
View
In ArcView 3 the View Window provides a means to display and query a collection of user-defined Themes.
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For other definitions please see the GIS Dictionary on the ArcGIS Resource Centre.

 

Portions of this document include intellectual property of ESRI and its licensors and are used herein under license. Copyright © [2010] ESRI and its licensors. All rights reserved.