satellites and sensors
Terms in this set (19)
Data aquisition: RS instrument measures energy in 3 useful areas of spectrum
1. visible/near/mid infrared
passive: solar energy, determine surface spectral reflectance
active: lidar (active laser pulse), time delay (height)
2. Thermal infrared
energy measured, temp of surface and emissivity
active: pulse transmitted measures amount scattered back
passive: emitted energy at shorter end of microwave spectrum
A remote sensing system
energy source atmosphere, object, platform/sensor, data recording/transmission&ground receiving station, data processing, expert interpretation/data users
From highest frequency and shortest wavelength to lowest frequency and longest wavelength. Gamma rays, x-rays, ultraviolet, visible light, near infrared, shortwave infrared, middle infrared, thermal infrared, microwaves, and radio waves.
Measurement of EM radiation
-intrinsic properties: emission, scattering, absorption
-energy source: sun/earth/artificial
-source properties: vary in intensity, vary across wavelengths, vary with physical/chemical properties, can vary with viewing angle
Spectral Signature (spectral curves)
for a given material the amount of solar radiation that reflects, absorbs, or transmits varies with wavelength, this important property of matter makes it possible to identify different substances or classes and separate them by their ________
Data collection platforms
-satellites, space shuttles. repetitive coverage of Earth's surface on a continuing basis
-aircraft, stable wing sometimes helicopter
image creation: scanner types
whiskbroom scanner, pushbroom
point sensor using rotating mirror, build up image as mirror scans, Landsat MSS, TM
array of sensing elements (line) simultaneously, build up line by line, SPOT
revolve at speeds that match the rotation of the Earth so they seem stationary. allows satellites to observe and collect continuous info over specific areas
orbit relative to line running btween N and S poles. opposite of Earth's rotation to cover most of the surface
spectral, spatial, radiometric, temporal
Wave length range/sensor, # of bands collected. ability of a sensor to define fine wavelength intervals. the finer the __________, the narrower the wavelength range for a particular channel or band
ground cover of pixel (28.5X28.5=30m) depends on IFOV instantaneous field of view & distance btwn ground/sensor. resolution cell. Landsat TM: 28.5X28.5m, SPOT:10x10m
# of bits stored, 8 bit=[values 0-255). finest distinction btwn objects viewed in the same part of the EM spectrum. ability to descriminate very slight differences in energy. finer=more sensitive to detecting small dif in reflected/emitted energy.
shortest time it takes for satellite to revisit a spot on earth, 16 days for landsat 5. Therefore the absolute temporal ________of a remote sensing system to image the exact same area at the same viewing angle a second time is equal to this period.
smallest discernible cell, determines a sensor's max spatial resolution. feature has to be size >= __________ to be detected
natural vs. false image display
the colour in __________ with layers of blue, green and red light looks normal to the human eye. In _________, targets with high near-infrared reflectance appear red, those with a high red reflectance appear green, and those with a high green reflectance appear blue, thus giving us a "_________" presentation of the targets relative to the colour we normally perceive them to be.
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