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Ordnance Survey - Glossary: mapping terminology and acronyms Category: Electronics and Engineering > mapping Date & country: 24/09/2007, UK Words: 414

Identifier
A form of identifying or labelling a feature. An identifier need not be unique or unambiguous. Types of identifier are address, text label and digital identifier.

Independent Polygon
One of the options for OS MasterMap product feature geometry/topology in which the data is simplified into area, point and line features with no relationship between them and with their own explicit geometry. For example, in the Independent Polygon product, the bounding line between two areas will be represented three times, each with its own description of the geometry: once as a line feature, once as part of the bounding line of the first area feature and once as the bounding line of the second area feature.

Inferred Links
Line features representing inferences about the real world, rather than topographic statements of fact. These sensibly subdivide certain types of area feature where there is no appropriate topographic detail. They are normally used to: divide road sections, separate individual garden plots in residential areas where no dividing fence, wall or hedge exists, close junctions btween roads and car parks or hard standing areas, close fields which have simple breaks in the hedge or wall rather than gates. These will be automatically created using software and initially OS expects to be able to create polygons for around 95% of urban areas using this method. Inferred links sensibly subdivide certain types of area feature where there is no appropriate topographic detail. Quality will be variable initially, but we are investigating methods of improving this information.

Integrated Services Digital Network
A telecommunications standard which enables the transmission of voice data and certain images over telephone lines through end-to-end digital circuits.

Internet
The combined collection of interconnected global computer networks that use TCP/IP protocols and are public domain i.e potentially available to all.

Internet Service Provider
Organisations that offer commercial connection to the Internet network.

Interoperability
See OpenGIS.

Interpolation
The estimation of values of a surface at an unsampled point based on the known values of surrounding points.

Intranet
A private network that uses Internet standards and protocols but enables full control within an organisation for the provision of corporate information and services to employees.

ISDN
See Integrated Services Digital Network.

ISO
See International Standards Organisation.

Isoline
A line joining points of equal value. Examples of these include height contours on a map or isobars showing atmospheric pressure on a weather map.

ISP
See Internet Service Provider.

Java
A full object-oriented programming language developed by Sun Microsystems. Java is architecturally neutral and portable in that it can support applications operating across a wide variety of operating systems.

JavaBeans
A component model for the Java programming language. Components written in Java can be 'plugged together' using the JavaBeans protocols.

JavaScript
An object-based language which enables non-programmers to create applications similar to Java. It supports only some of the functionality of Java in an effort to overcome some of its complex features.

Joint Photographic Experts Group
An organisation that has defined various file compression techniques. The most common graphics format on the Internet.

JPEG
See Joint Photographic Experts Group.

Land Information System
A system for capturing, storing, checking, integrating, manipulating, analysing and displaying data about land and its use, ownership and development.

Land Parcel
An area of land, usually bounded by real world features or implied alignments and usually with some implication for land ownership or land use.

Land Terrier
Traditionally a document system comprising a set of marked maps and ledgers containing textual information to record land and property - can be emulated by many GISs.

Large-Scale
The term used to refer to a map or map data that concentrates on small areas. It is called large scale because the features that appear on the map will look larger than those at a small scale. For example a building may appear as its outline (or footprint).

Laser Induced Direction and Range
Airborne laser scanning system which accurately measures DEMs. May be used for flood monitoring and prediction, building detection and building heighting, tree height measurement and general DEM production.

Latitude
The angular distance north or south between a point on the earth's surface and the equator. The distance is measured with reference to an idealised spheroid shape of the earth.

Layer
Equivalent to Theme.

Licensed Partner
Any organisation that has entered into a formal licence agreement with OS to market map information or to incorporate map data with their application or service. A Licensed Partner may also be a customer in their own right.

LIDAR
See Laser Induced Direction And Range.

Line
A series of connected coordinated points forming a simple feature with homogeneous attribution.

Line Feature
The spatial abstraction of an object in one dimension. Lines may intersect with other lines. They are defined as a series of two or more coordinate pairs and may be curved or straight. Curved lines consist of a series of very short straight line segments. Lines may be concurrent with other lines under certain conditions. As an object abstraction a line has no width.

Line Segment
A vector connecting two coordinate points.

Link or Edge
Links are the representation of line features. They are made up of one or more consecutive non-intersecting link segments with common attributes between two terminating nodes. Links have no connection with other links except at the start or end, via common (shared) terminating nodes (points). Al links contain their terminating coordinates. Links may form the boundaries of polygons and may be shared between polygons.

Link-Node Topology
A data structure used to represent connectivity between line features. Link-node topology supports the definition of linear feature and polygon boundaries and supports analysis functions such as network tracing.

LIS
See Land Information System.

Local Holdings
The situation where a customer has to hold and manage data which is supplied to them.

Logical Record
A logical record contains all the information relating to a data entity e.g. a feature record. A logical record may comprise one or more physical records.

Longitude
The angular distance of a point east or west of an arbitrarily defined meridian, usually taken to be the Greenwich meridian. The distance is measured with reference to an idealised shape of the earth.

Map Data
Digital data that has a spatial component. Typically these are digital maps but can also include data that has some form of spatial attribute that can be linked to a real world location - i.e an address.

Mean High Water-Springs
Depiction of the encroachment of land by tidal waters at mean highest levels - spring tides in Scotland.

Mean Low Water-Springs
Depiction of the limits of tidal waters at mean lowest ebb - spring tides in Scotland.

Metadata
Graphical or textual information about the content, quality, condition, origins and characteristics of data.

MHW or MHWS
See Mean High Water/Springs.

MLW or MLWS
See Mean Low Water/Springs.

Modelling
The process of creating a representation of part of the real world and subjecting it to some form of parameters and variables for the purpose of predicting, simulating or describing the real world.

Name or Text Feature
The proper name or label of an object (real world) or feature (object abstraction) consisting of one or more text strings. A name position is defined by a coordinate pair.

National Geospatial Data Framework
A UK initiative involving various public and private sector organisations involved in GIS and Map Data who want to create the infrastructure to make disparate data sets easily accessible.

National GPS Network
The infrastructure of active and passive GPS reference stations which allow surveyors to determine precise coordinates in GPS and British National Grid spatial reference systems. The National GPS Network provides the physical definition of the British National Grid, the primary spatial reference system used in the OS MasterMap. A central component of the OS MasterMap.

National Grid
A metric grid based on the Tranverse Mercator Projection developed by Ordnance Survey in 1936 for use in Great Britain. Referred to in GIS by the code 'OSGB36®' it is the de facto standard projection for display of UK based mapping.

National Land Information System
A conveyancy service designed to make the legal processes associated with buying a property more efficient. It combines land and property data with local authority information to cover the legally recuired local land search coving land charges and inform.

National Land Use Database
A database of land use. Currently contains information on brown field sites supplied by Local Authorities but will in the future cover the entire country and different land cover.

Neatline
The outer grid lines, forming the boundary of the map sheet.

Network
A model representing the interconnected elements through which some form of resource can be transmitted or will flow.

Newsgroups
Similar to Bulletin Boards except that the reader membership can be controlled. These are often used by more specialised groups for exchange of information where a common interest is held andcan vary in size depending on the size of audience intended.

NG
See National Grid.

NGDF
See National Geospatial Data Framework.

NLIS
See National Land Information System.

NLPG
See National Land and Property Gazetteer.

NLUD
See National Land Use Database.

Node
An object representation of a point which either does not form any part of a link (isolated node or polygon seed point; or is the representation of a point at the start or end of a link (terminating node). The position of a node is represented by a single coordunate pair; which is repeated within all links logically connected at that node and/or containing it.

Noise
In a scanning context this refers to random, incorrectly-read pixel values, normally die to electrical interference or device instability.

Northings
See Rectangular Coordinates.

Object
Object when referring to a geographic feature will not be used. Feature is the preferred term.

Object Database
Stores software objects rather than rows of data in tables.

Object Database Management Systems
The software which manages and controls an object database.

Object Orientation
A data model that treats components of a program or database as individual entities. These 'objects' encapsulate knowledge about how the entity responds and reacts to the system and inherits functionality from generic classes of objects.

Object-Based Data
Data inwhich one entity (i.e. One feature) represents one real world object (e.g. A building or land parcel).

ODBMS
See Object Database Management Systems.

Off-Line Supply
The supply off data to a customer on physical media (e.g. CD, DVD).

Office for National Statistics
UK government agency.

OGC
See Open GIS Consortium.

OGIS
Open Geodata Interoperability Specification.

Online
A computing device or program that is activated and ready for operation is said to be online.

Online Supply
The supply of data to a customer using Internet technologies.

ONS
See Office for National Statistics.

OO
See Object Orientation.

Open GIS Consortium
A consortium of vendors, producers and users of geospatial data dedicated to defining the standards to allow different GIS software components to internally exchange GI and requests and thus work seamlessly. This functionality is called interoperability.

Orbital Perturbation
The deviation of an orbit from some orbit taken as standard; in particular the deviation from a Keplerian orbit.

Ordnance Datum
The mean sea level at Newlyn in Cornwall calculated between 1915 and 1921, taken as a reference point for the height data on Ordnance Survey maps.

Ordnance Survey of Ireland
National mapping agency of Ireland.

Ordnance Survey of Northern Ireland
National mapping agency of Northern Ireland.

Orientation
Orientation of a point or a text feature measured in degrees anticlockwise from grid east.

Origin
The zero point in a system of rectangular Cartesian coordinates.

Orthogonal
At right angles to each other.

Orthoimage
See Orthophoto.

Orthophoto
Photographic image, rectified to remove the distortions caused by variations in terrain height, resulting in an image in which all pixels are to the same scale.

OSI
see Ordnance Survey of Ireland.

OSNI
See Ordnance Survey of Northern Ireland.

Overhaul
The process of refashioning the old County Series 1:2500 scale maps to adequate National Grid standards. It included the adjustment of the detail on the old maps to the control points of the 1936 retriangulation, the recompilation of the maps on the national Transverse Mercator Projection and with sheet lines corresponding to the National Grid., the elimination of errors (particularly those caused by distortion of materials and inadequacy of old revision methods), the revision of detail and finally, the fair drawing of all maps to a new specification. Early experiments were carried out in the Cotswolds and therefore the method is often referred to as the Cotswold Adjustment. Overhaul was carried out between 1948 and 1980.

PAF
See Postal Address File.

Paradigm
A set of assumptions, concepts, values and practices that constitutes a way of viwing reality for the community that shares them, especially in an intellectual discipline.

Parallel
A line of latitude.

Parameter
A quantity that is fixed for the case in question, but may vary in other cases.

Parcel
See Land Parcel.

Pay as You Use
A service provided by Licensed Partners giving access to Ordnance Survey data for business use on a transaction basis with or without added value services. The transactions available will be defined as View, Plot, Data Export and Analysis. The transaction will not include any update maintenance provision. Each access to the data will incur a data charge related to the type of transaction. In the case of data export, the data will include a business licence for a period of 12 months only.

PAYU
See Pay as You Use.

Period Licence
A licence to use a data product or any other value added service or product derived from detailed datasets for business use for an agreed period of one or more years. It covers the initial supply of the data and supply of update.

Perl
A scripting language popular for writing CGI applications due to its ability to create powerful data and text manipulation programs.

Perturbation
See Orbital Perturbation.

Photogrammetry
The science, art and technology of obtaining reliable measurements and maps from aerial photographs.

Pixel
A picture element of a raster image as displayed on a screen or raster plot.

Platform Independent
A term usually applied to a piece of software that can operate on many different hardware platforms e.g. PC, Unix, Mac, VAX etc.