Glossary/Dictionary of Remote Sensing for Risk Management

Access delay
    Average requiered delay before being able to transfer a request to the satellite. Mostly depend on the control centers.

Acquisition capability
    Average acquisition capacity according to on-board energy, downlink capacity and swath.

Along track
    Dimension parallel to the path of the platform carrying the sensor

B: -

CNES
    Centre National d'Etudes Spatiales

Cross track
    Dimension perpendicular to the path of the platform carrying the sensor.

Data rate
    Link capacity available for payload communications

dB
    Decibel, an expression of power ratio

DEM
    Digital Elevation Model A topographic surface arranged in a data file as a set of regularly spaced x, y, z coordinates where z represents elevation. A DTM represents the theoretical surface on the ground (without Building, Forest, ...) while a DEM represents the theoretical surface of high points.

Descending node
    The point at which an orbit crosses the ecliptic plane going south

Design life
    The design life of a component or product is the period of time during which the item is expected by its designers to work within its specified parameters; in other words, the life expectancy of the item.

DLR
    German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt)

DTM
    A digital terrain model (DTM) is a topographic model of the bare earth that can be manipulated by computer programs. A DTM represents the theoretical surface on the ground (without Building, Forest, ...) while a DEM represents the theoretical surface of high points.

E: -

Frequency
    Number of oscillations per unit time or number of wavelengths that pass a point per unit time.

GSD
    Ground Sampled Distance

HH
    Horizontal Transmit - Horizontal Receive Polarization

HV
    Horizontal transmit - Vertical receive polarization

Hyperspectral
    Simultaneous acquisition of images of the same area in many (usually 100 or more), narrow, contiguous, spectral bands.

IAI
    Israeli Aircraft Industries

IGN
    Institut G�ographique National

Incidence
    Angle defined by the incident radar beam and the vertical (normal) to the intercepting surface. In general, reflectivity from distributed scatterers decreases with increasing incidence angle.

Inclination
    The angular distance of the orbital plane from the plane of the planet's equator, stated in degrees.

JAXA
    Japan Aerospace Exploration Agency

JRC
    Joint Research Centre

K: -

L: -

MS
    Multispectral. Sets of data obtained simultaneously, but each set obtained by sensing a different part of the electromagnetic spectrum.

Multispectral
    Sets of data obtained simultaneously, but each set obtained by sensing a different part of the electromagnetic spectrum.

NASA
    National Aeronautics and Space Administration

NASDA
    National Space Development Agency of Japan. Merged in the Japan Aerospace Exploration Agency (JAXA) since October 1, 2003.

NDVI
    Normalized Difference Vegetation Index (NDVI) is a simple numerical indicator that can be used to analyze remote sensing measurements, typically but not necessarily from a space platform, and assess whether the target being observed contains live green vegetation or not.
Source : Wikipedia

NDWI
    Normalised Difference Water Index

NOAA
    National Oceanic and Atmospheric Administration

Noise equivalent sigma 0
    A measure of the sensitivity of a given SAR

Orbit cycle
    Time taken to re-visit the same spot above the earth's surface. The time taken to make a repeat measurement at a point on the earth's surface (revisit time) may be significantly reduced if the instrument has a wide swath width, depointing capabilities or if the point is at high latitude, where the orbit tracks are closer together.

PAN
    Panchromatic refers to black and white imagery exposed by all visible light. However, panchromatic photography and digital imagery is often acquired using a minus blue filter to reduce the scattering that occurs in those blue wavelengths.

Panchromatic
    Panchromatic refers to black and white imagery exposed by all visible light. However, panchromatic photography and digital imagery is often acquired using a minus blue filter to reduce the scattering that occurs in those blue wavelengths.

Payload
    Sensing equipment carried on a platform.

Period of revolution
    Duration of one orbit around the Earth.

Pitch
    Rotates around the axis perpendicular to the orbital plane (E-W on the earth)

Polar Orbit
    An orbit that passes close to the poles, thereby enabling a satellite to pass over most of the surface, except the immediate vicinity of the poles themselves.
Source : Lamont-Doherty Earth Observatory of Columbia University

Polar Sun Synchronous
    A polar orbit where the satellite always crosses the Equator at the same local solar time

Polarization
    A property of an electromagnetic wave that describes the locus of the electric field vector as a function of time.

Q: -

Remote sensing
    The technique of collecting information from a distance. Most common mediums used are satellite imagery (and aerial imagery).

Revisit time
    Average delay between two images of the same area. Depends on the latitude of the area, but also of some satellite specifications (altitude, depointing capacity)

Roll
    Rotates around the axis tangent to the orbital plane (N-S on the earth)

SAR
    Synthetic Aperture Radar

SPOT
    Satellite Pour l'Observation de la Terre

Sun-Synchronous Orbit
    A polar orbit where the satellite always crosses the Equator at the same local solar time

Supermode
    Supermode is an image sampling process that yields a 2.5 m image from two 5 m black-and-white images acquired simultaneously

Swath
    The width of the track covered by a sensing system. Also called the range.

Topographic map
    Topographic maps, also called contour maps are maps that show topography, or land contours, by means of contour lines. Contour lines are curves that connect contiguous points of the same altitude (isohypse). In other words, every point on the marked line of 100 m elevation is 100 m above mean sea level.
Source : WIKIPEDIA

USGS
    U.S. Geological Survey

VH
    Vertical transmit - Horizontal receive polarization

VV
    Vertical transmit - Vertical receive polarization

Wavelength
    Minimum distance between two events of a recurring feature in a periodic sequence, such as the crests in a wave. It is represented by the Greek letter lambda.
Source : CCRS

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Y: -

Z: -