Glossary
Introduction
The following section provides a glossary of terms that have been used through the website.
Glossary of Terms
|
ALOS |
Advanced Land Observing Satellite |
|
ASTER |
Advanced Spaceborne
Thermal Emission and Reflection Radiometer |
|
CASI |
Compact Airborne
Spectrographic Imagery sensor with 1 m spatial resolution, and 14 wavelength bands |
|
DEM |
Digital Elevation Model |
|
eCognition |
Specialised software that enables multi-resolution
segmentation of panchromatic or multi-spectral images into highly homogeneous
image objects in any chosen resolution. These image objects represent image
information in an abstracted form and serve as building blocks and an
information carrier for subsequent classification. |
|
Geographic Information System (GIS) |
A computer-based system designed to
input, store, manipulate, and output geographically referenced data. |
|
HyMap |
An airborne hyperspectral sensor with 2.5 m spatial resolution,
120 wavelength bands |
|
JERS |
Japanese Earth Resources Satellite |
|
Landsat |
The name given to a series of satellites, the first of which was launched in 1972. The prime sensors on board have been the: v Multi-Spectral Scanner
(MSS - 80-metre
pixels and four spectral bands), v Thematic Mapper (TM - 30-metre resolution and 7
spectral bands)
v Enhanced Thematic Mapper
(ETM+ - 30-metre
resolution, 7 spectral bands and an added panchromatic band with 15-metre resolution). |
|
-
HYPERION |
Landsat Hyperion provides an advanced
high-resolution hyperspectral imager (capable of resolving a large number of
spectral bands per pixel). Hyperion is capable of resolving 220 spectral bands
at wavelengths from 0.4 to 2.5 micrometers with a 30-meter resolution |
|
Normalised
Difference Vegetation Index (NDVI) |
A commonly used vegetation index calculated from
the red and near infrared (NIR) channels such that the NDVI =
(NIR-red)/(NIR+red) and values range from –1 to +1. Vegetation with higher
NDVI values are typically of greater productivity. |
|
Near Infrared (NIR) |
The region of the
electromagnetic spectrum between 0.7 and 1.3 μm. |
|
Radiance |
A measure of
the energy radiated by an object, expressed in W m2
sr-1 μm-1. |
|
Remote
Sensing |
The science and art of obtaining information about
an object, area or phenomenon through analysis of data acquired by a device
that is not in contact with the object, area or phenomenon under
investigation. |
|
Shortwave Infrared (SWIR) |
The region of the electromagnetic spectrum between
0.13 and 2.5 μm. |
|
Spatial resolution |
The size of the smallest possible
feature that can be detected on the ground and a measure of the resolving
power of the sensor expressed as cycles per unit length on the ground. As an example, the spatial resolution (or
pixel size) of the Landsat ETM+ is 30 m.
|
|
Spectral resolution |
The bandwidth across which electromagnetic energy is
recorded by different channels of remote sensing instruments. |
|
SPOT |
The
SPOT satellite Earth Observation System has been operational since 1986, with
SPOT 5 launching in May 2002. SPOT 5
carries the HRS high-resolution stereoscopic imaging instrument and the HRG
High Geometric Resolution instrument.
SPOT is a French acronym for Systeme Pour l'Observation de la Terre. |
|
Synthetic Aperture Radar (SAR) |
An active remote sensing instrument
that generates its own source of energy, typically at X-band (10 GHz or ~ 3
cm wavelength), C-band (5.3 GHz or ~ 6 cm), L-band (1.25 GHz or ~ 25 cm) or
P-band (0.4 GHz or ~ 68 cm). Signal
processing uses the magnitude and phase of received signals over successive
pulses from elements of a synthetic aperture to create an image. |
|
- PALSAR |
Phase Arrayed L-band SAR |
|
-
POLSAR |
Polarimetric SAR |
|
-
TOPSAR |
Topographic SAR |
|
Temporal
Resolution |
The frequency of observation by remote sensing
instruments. As an example, the temporal
resolution of the Landsat ETM+ is 16 days.
|
|
Visible Reflectance (VIS) |
The region of the electromagnetic spectrum that
can be perceived by the naked eye and is located between ~0.4 and 0.7
μm. |