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Glossary

A B C D E F G H I J K L M N O Q R S T U V W X Y Z

A

Absorption band: The wavelengths of electromagnetic radiation that are absorbed by a substance. Some components of the atmosphere have a number of absorption bands.
Access Grid: A collection of resources and technologies that enable audio and video-based collaboration between people in different locations.
Active microwave instrument: Radar systems carried abroad the European Radar Satellites comprising a SAR and wind scatterometer.
Aerial photography: A representation of a scene recorded on photographic film from the air. Acquisition platform is usually an aircraft.
AGN: Access Grid Node
Amplitude: Characteristic of an electromagnetic wave.
ASAR: Advanced Synthetic Aperture Radar.
Athens: The Athens system provides access management for subscription services provided by publishers and subscription agents.
AVHRR: Advanced Very High Resolution Radiometer.
Azimuth direction: A term used in radar to describe the direction in which the airborne sensor is moving.

B

Band: A wavelength range measured by a remote sensing system.
Bit: Abbreviation for binary digit; can be represented by zero or one. The term is analogous to quantum and represents the smallest discrete package of information.
Byte: A collection of eight bites (256 levels).

C

Cities Revealed: Cities Revealed datasets include multi-dated aerial photography, LiDAR height data, land use data, building heights and colour infrared. Cities Revealed is a trademark of The GeoInformation Group.
Contrast stretch: The procedure by which the input DN range for an image, which usually spans only a small part of the available DN, is increased to encompass a larger part of the available DN. This mathematical procedure increases the contrast of the image.
Correlation: In remote sensing, it is a measure of the degree to which the DN for one band can be predicted if the DN of another band is known.

D

Data Grid: A grid computing system that deals with the sharing and management of large amounts of distributed data.
DCMI: Dublin Core Metadata Initiative
Digital elevation model: A regular grid array of numbers in which the numbers represent elevation.
DMC: Disaster Monitoring Constellation (Geospatial)

E

EA: Environment Agency
EDINA: JISC- supported national data centre based at the University of Edinburgh
EGEE: Enabling Grids for E-sciencE
Electromagnetic spectrum: The range of wavelengths of frequencies of electromagnetic radiation.
ENVISAT: ENVIronment SATellite. Advanced polar-orbiting Earth observation satellite, lunched in March 2002 by the European Space Agency, which provides measurements of the atmosphere, ocean, land and ice.
EPSRC: Engineering and Physical Sciences Research Council
ERS: European Remote Sensing Satellite. ERS-1 and ERS-2.
ERS Satellite data: Radar remote sensing data used in the understanding of the Earth's processes.
e-Science: Large-scale science, often carried out through distributed global collaborations and requiring vary large-scale computing resources.
ESA: European Space Agency

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F

False colour composite: An image whose colours do not accord with those that would be seen with human eyes. False colour composites usually include at least one input band that is invisible to our eyes. projecting the green range in blue, the red range in green and the infrared range in red forms a standard false colour composite.
Federated Access: Federated Access (e.g. Shibboleth) allows users to securely access external services using the same username and password as they do for local services at their institution. See also Shibboleth.
Filter: A mathematical procedure that alters the digital numbers in an image.
Frequency: A property of an electromagnetic wave that is a measure of the number of wave crests passing a point in unit time. It is inversely proportional to wavelength.

G

GEES: Geography, Earth and Environmental Sciences
GEMS: Grid Enabling Mimas Services
GIS: Geographic Information System
GISc: Geographical Information Science
GML: Geography Markup Language
GPS: Global Positioning System
Grid: Refers to a computational grid, an infrastructure that enables coordinated resource sharing.
Ground control point (GCP): A point that can be located on both an image and a map which is used in the process of rectification. Such points are used to produce the mapping algorithms which change a distorted image into a geometrically correct one.

H

HRV: Acronym for High Resolution Visible that refers to the two sensors carried by SPOT.

I

ICT: Information and Communication Technology
IE: Information Environment. Aims to help provide convenient access to resources for research and learning through the use of resource discovery, resource management tools and the development of better services and practice.
IEA: Information Energy Agency
Image: A general term used to describe the representation of a scene obtained either photographically or digitally.
Image enhancement: The process by which data displayed on an image can be made more obvious to the human visual system.

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J

JISC: Joint Information Systems Committee. Supports further and higher education in the use of information and communications technology.

K

KML: Keyhole Markup Language

L

Landmap: The Service comprises orthorectified satellite images and mosaics of Landsat, SPOT, ERS and ENVISAT data; a high-resolution Digital Elevation Model for the British Isles; and the new Cities Revealed dataset (from The GeoInformation Group). Learning materials are also available.
Landsat: Archives of satellite data from Landsat, a programme for image acquisition form space.
LiDAR: Light Detection And Ranging. A technique used to measue distance, speed, rotation and chemical composition of a remote target.

M

MACE: School of Mechanical, Aerospace and Civil Engineering (The University of Manchester)
Map Projection: Process by which the elliptical Earth is represented on a two-dimensional surface.
Maximum likelihood classification: Classification procedure based on the assumption that training area datasets have a normal distribution, which involves that construction of probability contours.
Microwave: Part of the electromagnetic spectrum ranging from 0.1 cm to 1 m.
Middleware: Software that provides a service to other applications, e.g. authentication, security, searching, OpenURL resolvers.
Mimas: The JISC and ESRC supported national data centre, based at The University of Manchester, providing the UK HE, FE and research community with access to key data and information resources to support teaching, learning and research across a wide range of disciplines.
Mosaic: A number of aerial photographs or satellite images joined together in order to display a larger area.
Multispectral imagery: Imagery of an area that has been recorded in a number of wavebands.

N

NCeSS: National Centre for e-Social Science
NGS: National Grid Service. Production service for the UK academic community.

O

OGC: Open Geospatial Consortium (formerly Open GIS Consortium)
OGSA-DAI: OPen Grid Services Architecture Data Access and Integration Project. Develops middleware to assist with access and integration of data from separate sources via the grid.

P

Pixel: Picture elements; the smallest definable unit on a digital image.

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R

Radiance: The power emitted by a body per unit area per unit steradian.
Radiometric resolution: The number of grey levels measured by a digital system.
Remote sensing: The acquisition and recording of information about an object without being in direct contact with that object.
RSS: Really Simple Syndication (as in RSS feeds)
RSS feed: XML for web syndication, commonly used by news websites and weblogs (Blogs). They provide items with short descriptions of web content together with a link to the full version of the content.

S

Satellite: In remote sensing, an unmanned spacecraft which orbits the Earth obtaining data.
SARoNGS: Shibboleth Access for Resources on the National Grid Service
Scattering: The random propagation of electromagnetic radiation s a results of interaction with various components of the atmosphere. Selective scattering is wavelength dependent and, depending on the relative size of the particles compared with the wavelength of radiation, either Rayleigh or Mie scattering may occur. Rayleigh scattering is inversely proportional to the fourth power of wavelength and Mie scattering is inversely proportional to wavelength.
Shibboleth: Defines a set of protocols for the secure passing of identity information between institutions and service providers. It enables Federated Access Management. See also Federated Access.
SIDS: Satellite Image Data Service (see Landmap)
SOAP: A standard for exchanging XML data over a computer network.
Spatial resolution: A measure of the amount of detail that can be observed on an image.
SPOT: Series of French polar-orbiting satellites.
Supervised classification: A classification process in which an image is separated into a number of information classes based on the statistical characteristics of training areas outline by the operator .

T

Thematic map: A map produced by classifying an image in which a colour represents a specific theme.

U

Unsupervised classification: An automatic classification process in which the image is divided into a number of spectral classes based on DN distribution.
URL: Uniform Resource Locator. The address of a resource on the internet.

V

Visible light: That part of the electromagnetic spectrum that can be detected by the human visual system. It extends from 0.4 um to 0.7 um.

W

W3C: World Wide Web Consortium. Develops specifications, guidelines, software and tools for the web.
Waveband: A term used to describe a range of the electromagnetic spectrum.
Wavelength: Characteristic of an electromagnetic wave, being the distance from peak to peak.
WCS: Web Coverage Service. Supports electronic interchange of geospatial data as 'coverages', i.e. digital geospatial information representing space-varying phenomena.
Web 2.0: Refers to a perceived second generation of web-based communities and hosted services, such as social-networking websites, wikis, blogs and folksonomies, which facilitate collaboration and sharing between users.
Web Service: A software system designed to support interoperable machine-to-machine interaction over a network.
Web Standards: Established technologies designed to deliver the greatest benefits to the greatest number of web users while ensuring the long-term viability of any document published on the web. Usually relates specifically to the standards of best practice that have an impact both on web site usability and accessibility.
WFS: Web Feature Service. Allows a client to retrieve and up grate geospatial data encoded in Geography Markup Language (GML).
WMS: Web Map Service. International standard defining a 'map' to be a portrayal of geographic information as a digital image file. A map is not the data itself. WMS-produced maps are generally rendered in a pictorial format such as PNG, GIF or JPEG.
Web Services: A software system designed to support interoperable machine-to-machine interaction over a network.
Web Standards: General term for standards and technologies used on the web, or more specifically standards for best practice in developing websites.

X

XML: eXtensible Markup Language
XSLT: eXtensible Stylesheet Language Transformations

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Source: Gibson, J.P.(2000) Introductory Remote Sensing: Principles and Concepts.