Updated: 27 January 2006

Glossary of Terms (see also our Acronyms page)

| 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 |

A

ABRS Australian Biological Resources Study
ACA Australian Coastal Atlas
ACDSEE - shareware software owned and copyright to ACDSystems, CANADA. Used by GEODATA RASTER-250K to view images.
Active Sensing - remote sensing methods that provide their own source of electromagnetic radiation for illumination, for example, radar.
AEDD Arctic Environmental Data Dictionary (US)
AEGIS Australian Environmental Geographic Information System
AEOS Australian Environmental On-line Service
AFN Australian Fiducial Network - a network of permanent GPS satellite receivers, developed by Geoscience Australia for scientific and surveying applications - used as the primary framework for the Geocentric Datum of Australia (GDA).
AGD Australian Geodetic Datum - the framework used for coordinates in Australia since 1966. It is now being superseded by the Geocentric Datum of Australia (GDA).
AHD Australian Height Datum - the datum used for the determination of elevations in Australia. The determination used a national network of bench marks and tide gauges, and set mean sea level as zero elevation.
Altitude - the vertical distance of a level, a point or an object considered as a point, measured from mean sea level.
ALTS Automated Land Titles System (databases in Vic and NSW)
AMBIS Australian Maritime Boundaries Information System - a repository for reliable data relating to maritime jurisdictional limits.
AMG Australian Map Grid - a Cartesian coordinate system based on the Universal Transverse Mercator projection and the Australian Geodetic Datum. The unit of measure is the metre.
AMG Grid - grid derived from AMG coordinates.
AMI Active Microwave Instrument - active sensing system on-board ERS-1 and ERS-2 satellites which consists of two separate radars, operating at a frequency of 5.3ghz (c-band) with three modes of operation - a Synthetic Aperture Radar (SAR) for image and wave mode and a three antenna Wind Scatterometer.
AMI Australian Mapping Initiative - Geoscience Australia's revision program for 1:100 000 scale topographic mapping.
ANGIS Australian National Geoscientific Information System
ANN Australian National Network - a network of about 70 survey marks across Australia whose coordinates have been accurately determined by GPS observations. These sites, together with the AFN sites, form the basis of the Geocentric Datum of Australia (GDA).
AOS - Acquisition of Signal. Refers to the beginning of reception of satellite telemetry by an antenna when the satellite reaches a certain elevation above the horizon.
ARIES- Proposed Australian Earth resources satellite. The concept was developed by the CSIRO and, in conjunction was the ARIES project partners, carried out a feasibility study and costing into the building, launch and operation of the satellite. To date the project is still pending.
Array Sensor - an imaging device employing an array of electronically sampled detectors in the focal plane.
ASDD Australian Spatial Data Directory
ASDI Australian Spatial Data Infrastructure
Ascending node - the point on a satellite's orbit when a satellite crosses the Earth's Equatorial plane from South to North.
ASGC Australian Standard Geographic Classification (ABS)
Atmospheric correction - image processing procedure that compensates for the effects of scattered and absorbed radiation by the atmosphere.
ATS Antarctic Treaty System
Attribute - a descriptive characteristic of a feature. An attribute has a defined set of attribute values.
Attribute accuracy - component of data quality describing the likelihood of an attribute of a spatial feature being erroneous.
ATSR-M - along-track scanning radiometer with microwave sounder (ERS).
Australia Unfolded - Geoscience Australia's interactive atlas on CD-ROM used for making customised maps of Australia.
Automated cartography - the preparation and presentation of maps using machines controlled by computers.
AVHRR Advanced Very High Resolution Radiometer - sensor on-board the NOAA series of satellites.
Azimuth - geographic orientation of a line given as an angle measurement in degrees clockwise from north.
Azimuth range - for radar images this term represents the distance measured along a line between the limits of the radar beam in the direction of the satellite or aircraft.

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B

Band - a selection of a wavelength interval in the electromagnetic spectrum.
Band-pass filter - a wave filter that has a single transmission band extending from a lower cutoff frequency greater than zero to a finite upper cutoff frequency.
Bandwidth - the number of cycles per second between the limits of a frequency band.
Base mapping - usually associated with topographic mapping covering country or region at different scales.
Bathymetric surveying - is the measure of the depth and shape of the ocean floor. Usually associated with the mapping of the resources of the sea bed.
BIL Band Interleaved by Line, a data format used to store satellite imagery on digital media.
BIOMASS Biological Investigations of Marine Antarctic Systems and Stocks
BIS Bio-Geographic Information System
BMP - an abbreviation for Windows Bitmap. BMP is a common raster data format supported by many Microsoft Windows products and applications.
Brightness - the attribute of visual perception in accordance with which an area appears to emit more or less light.

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C

Cadastral survey - a survey of the boundaries of land parcels.
Cadastre - a public register usually recording the quantity, value and ownership of land parcels in a country or jurisdiction.
Calibration - the act or process of comparing certain specific measurements in an instrument with a standard.
CAMRIS Coastal and Marine Resources Information System
Cartography - the art and science of producing maps, charts and other representations to spatial relationships.
CCD Charged Coupled Device - a device in which electrons are stored at the surface of a semiconductor.
CCT Computer Compatible Tape - a one quarter inch magnetic tape reel which is used to store digital data.
Cell - an area on the ground from which electromagnetic radiation is emitted or reflected.
CGAComposite Gazetteer of Antarctica
Change detection - sensing of environmental changes between two or more time periods.
Characteristic curve - a curve showing the relationship between exposure and resulting density in a photograph image, usually plotted as density (D) against the logarithm of the exposure (log E) in candela- meter-seconds. It is also called the H and D curve, the sensitometric curve, and the D log E.
Chemical fog - density produced on photographic paper or films by chemical means, such as too energetic or contaminated developer.
COGIS Cooperative Geographic Information System (ACT Govt)
COMARIS Coastal Marine Information System
Completeness - component of data quality describing the completeness of coverage within a data set(s).
Contour - an imaginary line drawn on a map joining all the points on the earth that are the same height above sea level.
Control - a system of points which are used as fixed references for positioning other surveyed features.
Control, ground - control obtained by ground surveys as distinguished from control obtained by photogrammetric methods; may be for horizontal or vertical control, or both. Ground (in-situ) observations to aid in the interpretation of remote sensing data.
Control point - any station in a horizontal and/or vertical control system that is identified on a photograph or digital image and used for correlating the data shown on that photograph/image.
Coordinates - linear or angular quantities which designate the position of a point in a given reference or grid system.
Coordinate, geographic - a system of spherical coordinates for describing the positions of points on the earth. The declinations and polar bearings in this system are the latitudes and longitudes respectively.
Coordinates, grid - a plane-rectangular coordinate system based on and mathematically adjusted to a map projection in order that geographic positions (latitudes and longitudes) may be readily transformed into plane coordinates and the computations relating to them made by the ordinary methods of plane surveying.
COPYFILE - shareware software owned and copyright by Informatix Inc, USA. Used by GEODATA RASTER-250K to reformat the raster data.
CP Centering Point or Control Point
CSLX Commonwealth State Land Exchange (Agreement)

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D

DAF Data Acquisition Facility - ACRES satellite receiving station at Alice Springs, Northern Territory, Australia.
Datum - a mathematical surface on which a mapping and coordinate system is based.
DCDB Digital Cadastral Database
DCX - a raster image format, and is a variation of PCX file. DCX is used by many MS-DOS fax boards.
DEM Digital Elevation Model - a geographic grid of an area where the contents of each grid cell represents the height of the terrain in that cell. Consists of X, Y and Z coordinates.
Descending node - point on the orbit of a satellite when a satellite crosses the Earth's equatorial plane while moving from north to south.
DGPS Differential Global Positioning System - using two GPS satellite receivers with one at a known position it is possible to increase the accuracy from a roving receiver by applying corrections derived from the fixed receiver.
DIGEST Digital Geographic Information Exchange Standard
Digital mapping system - a system for compiling spatial data directly in digital form.
Digital Quick Look System- a software application at ACRES that provides users with access to image thumbnails and text meta-data of archived satellite images via the Internet World Wide Web.
Distortion - any shift in the position of an image on a photograph which alters the perspective characteristics of the photograph. Compressionor expansion of the scale of the imagery in the azimuth direction. Change in scale from one part of the imagery to another.
Downlink - a communication link between a satellite and a ground station.
DORIS Doppler Orbitography and Radiopositioning Integrated by Satellite
DPF Data Processing Facility - ACRES satellite data processing centre in Canberra, Australia.
DPI - dots per inch.
Dynamic range - the ratio of maximum measurable signal to minimum detectable signal.

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E

EDM Electronic Distance Measurement - measurement of distance by means of electro-magnetic transmissions, including radio, visible high, laser and infra-red light.
EIA Environmental Impact Assessment
EIS Environmental Impact Statement
Elevation - the vertical distance from a datum, usually mean sea level, to a point or object on the earth's surface.
EMR Electromagnetic Radiation - energy propagated through space or through material media in the form of an advancing interaction between electric and magnetic fields.
Engineering surveying - surveying associated with the setting out and monitoring of engineering or construction works.
Enhancement, image - the process of altering the appearance of an image to extract additional information. It may be accomplished by digital or photographic (optical) methods.
EOS Earth Observing Satellite
ERC Earth Rotation Correction
ERS European Remote Sensing Satellite - ERS-1was launched 17 July 1991 and operates in a near circular sun synchronous orbit with a period of 100 minutes. The satellite altitude is 785km. The repeat coverage cycle varies, depending on mission requirements, and includes 3, 35 and 168 day cycles. ERS-2 was launched 20 April 1995 and has the same orbit parameters as ERS-1.

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F

FERIS Forest Environmental and Resources Information System (QLD)
Frequency - the number of oscillations per unit time or number of wavelengths that pass a point per time.

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G

GCOS Global Climate Observing System
GDA Geocentric Datum of Australia - a new coordinate framework for Australia which is compatible with the Global Positioning System (GPS). The GDA was adopted in 1994 and will be implemented by the year 2000.
Geocentric Datum - a datum which has its origin at the Earth's centre of mass. The advantage of the geocentric datum is that it is directly compatible with satellite-based navigation systems.
GEODATA products - comprise Geoscience Australia map information converted into digital format. Used in conjunction with geographic information systems GEODATA products assist applications such as resource management, environmental assessment, mineral prospecting, communications and transportation planning.
GEODATA RASTER-250K - digital raster data product from Geoscience Australia. The product contains scanned images of all the 1:250 000 topographic map series for Australia.
GEODATA TOPO-250K - Geoscience Australia's digital, GIS-ready, vector, topographic data derived from 1:250 000 scale mapping and covering all of Australia.
Geodesy - the study of the size and shape of the Earth's surface, the measurement of the position and motion of points on the surface and the configuration and area of large portions of its surface.
Geodetic control - a network of sites for which precise positions and/or heights are known and for which the shape and size of the Earth are taken into account.
Geodetic surveying - surveying which takes into account the shape and size of the earth. The result of a geodetic survey is a continuous series of accurately marked points on the ground, to which topographic, land and engineering surveys can be related to provide additional coordinated points for mapping and other purposes.
Geographical coordinates - a position given in terms of latitude and longitude.
Geographical grid - grid derived from geographical coordinates (commonly referred to as longitude and latitude).
Geometric correction - the removal of sensor, platform, or scene induced geometric errors such that the data conforms to a desired projection. This involves the creation of a new digital image by resampling the input digital image.
GEOREFERENCED - digital spatial data (and non-digital map features) for which the coordinates or location can be determined.
GESMAR Geodetic Survey Marks Register (WA)
GIANT Geodetic Infrastructure in Antarctica
GICS Geocoded Image Correction System - an image processing system employed at ACRES used to produce Landsat TM and SPOT panchromatic and multispectral satellite image products.
GIF Graphics Interchange Format - the image file format originally developed by CompuServe as a machine-independent image file format. GIF files are a popular way of storing 8 bit, scanned or digitised images, and the compression ratios achieved are commonly better than other 8 bit formats. This format is commonly used in Internet applications.
GIS Geographic Information System - a computer-based system used to capture, create, maintain, display and analyse spatially-related information.
GLOBE Global Land One Kilometer Base Elevation project
GLONASS Global Navigation Satellite System
GLOSS Global Sea Level Observing System
GNSS Global Navigation Satellite System
GOOS Global Ocean Observing System
GPS Global Positioning System - is a satellite based navigation system developed by the United States Department of Defense and widely used for civilian navigation and positioning.
Graticule - a network of lines on a map or chart representing the parallels of latitude and meridians of longitude of the earth.
Grey scale - a monochrome strip of tones ranging from white to black with intermediate shades of grey. The scale is placed in a setup for a colour photograph and serves as a means of balancing the separation negatives and colour dye images.
Grid - two sets of parallel lines intersecting at right angles and forming squares. A rectangular cartesian coordinate system that is superimposed on maps, charts and similar representations of the earth's surface in an accurate and consistent manner to permit identification of ground locations with respect to other locations and the computation of direction and distance to other points.
Grid convergence - the angular difference in direction between Grid North and True North. It is measured east or west from True North.
GRNS Global Research Network System (Japan)
Ground Station - a facility capable of receiving signals from earth observation satellites such as LANDSAT, SPOT, ERS and RADARSAT.
Ground Resolution Cell - the area on the ground that is covered by the IFOV of a detector.
GRS Grille de Reference SPOT - the system of using a path and row combination to identify nominal scene positioning for data from the SPOT satellites.
GSDI Global Spatial Data Infrastructure

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H

HDDT High Density Digital Tape - one inch magnetic tape containing data from a remote sensing satellite and recorded in a compressed format.
HISPID Herbarium Standards & Protocols for the Interchange of Data
HRV Haute Resolution dans le Visible - the name given to the multispectral radiometer designed for SPOT spacecraft and offering high resolution in the visible and near-infrared. The first three SPOT spacecraft (SPOT-1,-2,-3) carry two identical HRVs designed for operation in a number of viewing configurations and in different spectral modes.
HRVIR Haute Resolution Visible Infra Rouge, a sensor on board the SPOT 4 satellite.
Hydrography - features both natural and constructed of which water is the main constituent, either permanently or intermittently.
Hydrographic surveying - the measurement and description of the physical features offshore and adjoining coastal areas with special reference to their use for the purpose of navigation.
Hypsometric tints - colours on a map depicting variations in the height of the earth's surface above sea level.

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I

ICMISS Integrated Catchment Management Information and Support System
IFOV Instantaneous Field Of View - is the angle contained by the minimum area that can be detected by a scanner.
IGAE Intergovernmental Agreement on the Environment
IGPB International Geosphere-Biosphere Program
IGS International GPS Geodynamics Service
IMAGINE - software owned and copyright to ERDAS, USA. Used to update RASTER-250K map images.
INASP International Network for the Availability of Scientific Publications
INSP Integrated National Space Program
IR Infra-Red, part of the electro-magnetic spectrum ranging from 0.7 micrometres to 1000 micrometres.
IMW International Map of the World - 1:1 million scale series.
IRS Indian Remote Sensing Satellite - IRS 1b launched August 1991. IRS 1c launched September 1995. IRS 1c operates in a sun synchronous orbit at an altitude of 817km with an orbital period of 101 minutes.

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J

JERS-1 Japanese Earth Resources Satellite - JERS-1 (also referred to as FUYO-1) was launched 11 February 1992 and operates in a sunsynchronous orbit at an altitude of 568km. Orbital period is 96 minutes and the repeat coverage cycle is 44 days.
JNC Jet Navigation Map - 1:5 million scale series produced by the Department of Defence.
JOG Joint Operations Graphic - a map series at 1:250 000 scale developed by the Royal Australian Army, primarily for defence personnel use. Two versions, Air and Ground, are produced.

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K

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L

Landsat - earth observation satellites. Landsat 5, launched in March 1994 and operated by Space Imaging, USA, operates in a near polar sun synchronous orbit at an altitude of 705km, has a repeat cycle of 16 days and is still operational. Landsat 7, launched in April 1999 and operated by USGS, is equipped with the new Enhanced Thematic Mapper Plus sensor which has the same 7 spectral bands as its predecessor, TM, but has an added panchromatic band with 15 metre resolution and a higher resolution thermal band of 60 metres.
Latitude - the latitude of a place is its angular distance on a meridian, measured northwards or southwards from the terrestrial Equator.
Legal cadastre - a cadastre compiled so that the jurisdiction may have a record of ownership of all land parcels.
LGA Local Government Area>
Lineage - component of data quality describing the history or origin of features within the described data set.
LIS Land Information System - synonomous with GIS although more often associated with cadastral based systems.
Longitude - a linear or angular distance measured east or west from a reference meridian (usually Greenwich) on a sphere or spheroid.
Look angle (radar) - the direction of the look, or direction, in which the antenna is pointing when transmitting and receiving from a particular cell.
LOS Loss of Signal. Refers to the end of reception of satellite telemetry by an antenna when the satellite declines to a certain elevation below the horizon.
LOTS Land Ownership and Tenure System (SA's Cadastral LIS)
LUT Look-Up Table
LZW compression - a compression routine for raster data, patented and owned by Unisys Corporation of the United States of America.

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M

Map - a representation of the earth's surface. A cadastral map is one showing the land subdivided into units of ownership; a topographic map is one showing the physical and superficial features as they appear on the ground; a thematic map displays a particular theme, such as vegetation or population density.
Map Grid of Australia 1994 (MGA94)- a cartesian coordinate system based on the Universal Transverse Mercator projection and the Geocentric Datum of Australia 1994. The unit of measure is the metre.
Map projectionx- any systematic way of representing the meridians and parallels of the earth upon a plane surface.
Mbps Megabits per second - the rate of transfer of binary information in millions of bits per second and commonly referred to in data transmission rates from satellites to ground stations.
MCDD Marine and Coastal Data Directory
Mean High Water (MHW) - the average height of all high waters at a place over an 18.6 year period. On small and medium scale maps, Mean High Water coincides with the coastline.
Mercator projection - the conformal cylindrical projection tangential to the Equator, possessing the additional valuable property that all rhumb lines are represented by straight lines. Used extensively for hydrographic and aeronautical charts.
Metadata - summary information describing the content of a dataset.
MGI Military Geographic Information
Mining surveying - associated with the construction, monitoring and mapping of mines and associated works.
MLA Multispectral Linear Array>
MMOFE Mission Management Organization Front End - NASDA's mission management computer.
MNF Master Names File - an Geoscience Australia product containing detailed list of place and locality names with coordinates and map sheet details.
MOS Marine Observation Satellite (Japan)
Mosaicking - the assembling of photographs or other images whose edges are cut and matched to form a continuous photographic representation of a portion of the earth's surface.
MOSS Modelling of Surface Systems
MSS Multi-spectral Scanner - a sensor on board LANDSAT 4 and 5 that records four bands of digital data in the visible/near infrared region of the electromagnetic spectrum.
Multipurpose cadastre - a cadastre containing a variety of parcel-based information considered necessary for good land administration.
Multispectral - generally used for acquisition of remote sensing data in two or more spectral bands.
MW Microwave

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N

Nadir - that point on the ground vertically beneath the perspective centre of the camera lens or satellite sensor.
National Gazetteer - an ICSM product distributed through .
NATMAP - the product name of the paper topographic maps published by Geoscience Australia.
NatMIS National Marine Information System
Nautical mile - a measure of distance equal to one minute of arc of a great circle on the earth's surface. The International Nautical Mile is equal to 1852 metres.
NBMS National Bathymetric Map Series
NFI National Forests Inventory
NIR Near Infra-Red. Part of the electro-magnetic spectrum ranging from 0.7 to 1.1 micrometres.
NSCD National Spatial Cadastral Database
NSDI National Spatial Data Infrastructure (USA and others)
NTDB National Topographic Data Base
NTMS National Topographic Map Series - a civilian map series comprising a set of consistent topographic maps nation-wide, at scales of 1:100 000 and 1:250 000.
Number of looks (radar) - this term refers to the successive observations of the same area as the antenna moves along its designated path. Many observations may be required in order to characterise the backscatter properties of a surface.

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O

ONC Operational Navigation Chart - 1:1 million scale produced by DMGI-A
Orbit - path of a satellite around the earth.
Orbital elements - a set of parameters defining the orbit of a satellite. Also called orbital parameters.
Orbital period - the time taken by a satellite to make one revolution around the earth. Also referred to as the anomalous or nodal period.
Orbview - Series of privately-owned U.S. Earth resources satellites. Orbview-1 was successfully launched on 3 April, 1995. Orbiew-2 followed on 1 August 1997 and Orbview-3 is scheduled for launch sometime in 1999. Orbview-4 is under development in Orbital's Space Systems Group facility in the U.S., and is expected to be launched the following year. The constellation of satellites provide for complete land, ocean and atmospheric coverage of the Earth.
Orthographic projection - the projection by parallel rays onto a plane at right angles to the rays.
Orthophotomaps - aerial maps, true to scale.

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P

Path - the number of the north/south track of the satellite in its specific satellite grid. LANDSAT uses the WRS and SPOT the GRS. For LANDSAT, in the visibility circle for the Alice Springs receiving station, the path range is 84 to 117, from east to west.
PCX - raster data format originally developed by Zsoft and extensively used in IBM PC computer applications.
Perennial - natural hydrographic features which normally contain water for the whole year, except during unusually dry periods, in at least nine years out of ten.
Photogrammetry - the science and art of obtaining measurements from photographs.
PHOTOSHOP - software owned and copyright to ADOBE, USA. Used to edit and enhance GEODATA RASTER-250K map images.
Pixel - a contraction of the words 'picture element'. A data element having both spatial and spectral aspects. The spatial variable defines the size of the resolution cell (i.e. the area on the ground represented by the data values), and the spectral variable defines the intensity of the spectral response for that cell in a particular channel.
PLA Panchromatic Linear Array- the single band sensor onboard the SPOT 1, 2, and 3 spacecraft.
Polarisation - the direction of vibration of the electrical field vector of electromagnetic radiation.
Positional Accuracy - statistical estimate of the degree to which planimetric coordinates and elevations of features agree with their real world values.

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Q

QSIS Queensland Land Information Directory
QSIS Queensland Spatial Information Strategy
Quantization - the process of converting from continuous values of information to a finite number of discrete values.

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R

RADARSAT - the earth observation satellite launched 4 November 1995 and operated by the Canadian Space Agency (CSA). RADARSAT is equipped with a C-band SAR which can be operated in a variety of modes with swath widths ranging from 35 kilometres to 500 kilometres and with resolutions from 10 metres to 100 metres respectively.
Radiance - a measure of the energy radiated by an object per unit area in a radial direction, eg watts per metre squared per steradian (W/m²/Sr)
Raster Data - a picture or image composed of rows and columns of data cells (pixels). Satellite data and GEODATA RASTER-250K are examples of raster data.
Raster Image - a cellular data structure composed of rows and columns. Each cell has a value which represents an attribute value for the feature represented by that group of cells.
Relief - the deviation of an area of the earth's surface from a plane. It refers to the physical shape of the surface of the earth.
Relief Displacement - a shift in position of the optical image of an object caused by the height of the object above or depth below a datum plane.
Remote sensing - the acquisition of information about an object without physical contact. Usually associated with the acquisition of information about the Earth's surface by electronic and/or optical instruments from satellites, airborne platforms or ground observation.
Repeat Cycle - cycle time for a satellite to pass over a given point on the earth.
Repromat - colour-separated reproduction material on a stable base used for the printing of maps.
RESURS - Launched on 4 November 1994, RESURS-O1 is the third in a series of Russian RESURS satellites designed for environmental monitoring and mapping Earth’s natural resources.
Row - the number of the east/west grid line in the specific satellite grid. LANDSAT uses the WRS and SPOT the GRS. For LANDSAT, in the visibility circle for the Alice Springs receiving station, the row range is 61 to 91, from north to south.

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S

SAR Synthetic Aperture Radar - active radar system in which high azimuth resolution is achieved by storing and processing data on the Doppler Shift of mutiple return pulses in such a way as to give the effect of a much longer antenna.
Scale - the indication given on a map, either as a linear scale or representative fraction, of the ratio between a given distance on the map and the corresponding distance on the earth's surface.
SDTS Spatial Data Transfer Standard
Sensor - any device which gathers electro-magnetic radiation or other energy and presents it in a form suitable for obtaining information about the environment.
Slant Range - for radar images this term represents the distance measured along a line between the antenna and the target.
SLR Satellite Laser Ranging - the measurement of the distance to a satellite fitted with retro-reflectors, by measuring the time taken for a laser beam to travel to the satellite and back. These measurements are used to determine satellite orbits and to monitor the movement of the earth.
SOE State of the Environment
SO-GLOBEC Southern Ocean - Global Ocean Ecosystems Dynamics Research
SO-JGOFS Southern Ocean - Joint Global Ocean Flux Study
SOS Satellite Operations Services (ACRES) - ACRES specialised unit, the primary responsibilities for which include the management of all client satellite programming requests for Landsat, SPOT, ERS and RADARSAT data. In addition, a secondary responsibility includes the management of the long and short term satellite acquisition planning for the ACRES image archive program.
Spectral band - an interval in the electromagnetic spectrum defined by two wavelengths, frequencies, or wave numbers.
SPOT Satellite Pour L'Observation de la Terre - the SPOT series of earth observation satellites are operated by CNES, France. SPOT 1 was launched 22 February 1986, SPOT 2 was launched 21 January 1990 and is currently operational and SPOT 3 was launched 26 September 1993 and is currently fully operational. SPOT satellites are operated in a sun synchronous near polar orbit and image via two sensors in the optical area of the elctro-magnetic spectrum. Satellite altitude is 830km and the repeat cycle is 26 days. SPOT 4, launched on 24 March 1998, has an additional sensor. The HRVIR will extend the imaging capabilities of the SPOT satellites into the short-wave infrared region of the electromagnetic spectrum.
SPOT-LITE - detailed satellite images of Australia, derived from data by the panchromatic sensor on board the SPOT satellites, which can be purchased and downloaded directly from Geoscience Australia's web site. Each "tile" covers an area of approximately 25km by 25km.
Stereoscopic pair - two images of the same area taken from different camera stations so as to afford stereoscopic vision; frequently called stereopair.
Stereoscopic plotting instrument - an instrument for plotting a map or obtaining spatial solutions by observation of stereoscopic models formed by stereopairs of images.
Sun synchronous - earth satellite orbit in which the orbital plane is near polar and the satellite passes over points on the earth at the same latitude at the same local sun time.
Surveying - measurement of dimensions (contour, position, boundaries, area, height etc.) of any part of the earth's surface (land or water) or any cultural feature. Depending on the type of survey undertaken and the degree of accuracy required, "surveys" may involve the application of the theory, principles and techniques of geodesy, photogrammetry and cartography.
SWIR Short Wave Infra-Red. Part of the electro-magnetic spectrum ranging from 1 to 3 micrometres.

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T

TARDIS Titles Automated Register and Document Information System (ACT)
TASMAP Maps produced by the Tasmanian Department of Environment and Land Management.
Telemetry - radio signals transmitted between satellites and ground stations.
TERSS Tasmanian Earth Resources Satellite Station - satellite data acquisition station located in Hobart, Tasmania and operated by ACRES for the TERSS Board.
TIFF Tagged Information File Format - raster image format created by Aldus and Microsoft Corporations and designed to be a universal format. It is used extensively in desktop publishing packages. TIFF can be compressed using a wide range of compression routines. The most common of these is LZW.
TIR Thermal Infra-Red
Title - the evidence of a person's right to land.
TM Thematic Mapper - a scanner on-board the LANDSAT 4 and 5 satellites that records seven bands of digital data in the visible and infrared areas of the electromagnetic spectrum .
Topographic surveying - involves establishing the contour level and interval of the earth's surface above and below sea level based on a particular control survey system. These surveys may be done by aerial, photogrammetric and ground survey and involves recording of natural features such as hills, streams, valleys and cultural features, such as roads, bridges, railways, etc. These surveys are used to produce topographic maps.
Topography- description or representation on a map of the physical and cultural surface features.
TOPO-250K - the national, topographic vector GEODATA product primarily sourced from the 1:250 000 scale NTMS.
Torrens title - a title registered in the manner advocated by Sir Robert Torrens in South Australia.
TPC Tactical Pilotage Chart - at 1:500 000 scale produced by the Department of Defence.
Transverse Mercator projection (TM) - A conformal cylindrical map projection, originally devised by Gauss, also known as the Gauss-Kruaer projection. As its name implies, its construction is on the same principle as the Mercator projection, the only difference being that the great circle of tangency is now any nominated meridian. Meridians and parallels are curved lines, except for the central meridian or a specified zone (meridian of tangency), which remains a straight line. Projection zones are established about the central meridian and vary in width from two degrees to six degrees of longitude, with some overlap between zones. The amount of scale distortion may become unacceptable at distances greater than about 1.5 degrees in longitude from the central meridian. In a modified form the projection is in general use for topographic mapping at scales of 1:250 000 and larger. See Universal Transverse Mercator projection.

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U

UNCED UN Conference on Environment and Development
UNCLOS United Nations Convention on Law of the Sea
Universal Transverse Mercator (UTM) A world wide systematic application of the Transverse Mercator Projection applying to the region between 80 degrees S and 84 degrees N latitude. The UTM is a modified TM projection whereby the natural scale of the central meridian is scaled by a factor of 0.9996 to enable a wider area to be mapped with acceptable distortion. Each Zone is six degrees of longitude in width with a half degree of overlap within the adjoining zone and having a true origin at the intersection of the central meridian of that zone and the Equator.
UV Ultra-Violet. Part of the electro-magentic spectrum ranging from 0.03 to 0.4 micrometres.

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V

Vector data - spatial data in which the location of features is defined by points and straight lines (vectors). A road network would be described by vector data.
VLBI Very Long Baseline Interferometry

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W

WAC World Aeronautical Chart - 1:1 million scale produced for civil aviation purposes.
WCRP World Climate Research Programme
Wavelength - The distance between successive wave crests or other equivalent points in a harmonic wave.
WGS84 World Geodetic System 1984 - a geocentric geodetic datum used for the determination of geographical coordinates developed by the United States Department of Defence. For all practical purposes, GDA94 approximates to WGS84.
WRS World Reference System - the system of using a path and row combination to identify nominal scene positioning for data from the MSS and TM sensors on the LANDSAT satellite.