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22 Cards in this Set
- Front
- Back
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History of remote sensing |
During WWII infrared detectors were very important because they could tell the difference between real vegitation and green camoflouge, this led to military development of multi spectral remote sensing research after the war.
After WWII US army scientists took the first photo of earth from space. (white sand New Mexico) using a german V-2 Rocket.
The strategic Satellite System was put together by the Air Force in the mid-50's.
in 1957 the soviets launched sputnik 1 nd started the space race.
Also in 1960's NASA started the space observation program in satellite remote sensing. They were not interested in a civilian satellite program because they were worried it would take away time and resources from them to mandate their mission to put a man on the moon. The national security council also did not like the civilian community looking at the earth at all.
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Development of Landsat program |
in 1972 Earth Recources Technology Satellite (ERTS) was launched marking the 1st generation of the US earth recource satellite.
in 1975 ERTS changed name to Landsat, and Landsat 2 was launched. 1978- landsat 3 was launched 1982- landsat 4 was launched 1984- Landsat 5 was launched
1985- EOSAT was put under a 10 year contract to operate Landsat system, they operated Landsat 4 and 5
1993- landsat 6 was destroyed during launch 1999- Landsat 7 was launched
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Electro magnetic radiation
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EMR is the foundation of aerial photographic interpretation and remote sensing
propagation of solar energy can be described in 2 ways:
electromagnetic waves- occur in a continuum and quanta- minimum measurable energy units known as photons
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Basic concepts of EMR:
Different spectrums at various wavelengths |
x-ray: <0.3 um
UV: 0.03-0.4um
Visible: 0.4-0.7um
Near-IR (reflected): 0.7-1.5um
Short IR: 1.5-3.0um
Mid-IR: 3.0-5.5um
Far-IR(thermal) 5.5mm-1mm
microwave can be from 11mm to 1000mm
the limits of electromagnetic spectrum are not yet fully known
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Basic conecpts of EMR:
Radiation between sun and earth |
The radiant power peaks with continuous spectrum produced by the sun approximates a "black body" at 6000k
a black body is defined as a body which absorbs and re-radiates all energy fallen upon it
the peak solar radiance striking the earth is about .47-.05um (green spectrum)
about 46% of the solar enerfy striking the earth falls between .4-.7um
therefore the sun is an excellent source of energy for measuring the reflectance of objects or scenes in the visible spectrum
the earth has an average ambient temp of about 300k
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Wave theory vs particle theory (compare and contrast):
wave theory |
James Clark Maxwell introduced the studys that state EMR travels as the speed of light in a WAVE pattern
the WAVE pattern consists of 2 force fields electric and magnetic running orthogonal to each other and perpendicular to the direction of propagation
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Wave theory vs particle theory (compare and contrast):
Particle theory |
Max Karl Ernst is the founder of PARTICLE theory
according to max EMR can behave as a wave or as a particle
in the particle model of EMR a wave consists of discrete packets of energy, or quanta called photons |
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Wave theory vs particle theory (compare and contrast):
wave parameters
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Wave theory: frequency- # of vibrations per second wavelength- distance between two adjacent wave crests period- time required for the passing of one complete wave amplitude- the height of the wave
The speed of light is directly related to frequency and wavelength and period and
the higher the energy source the higher the frequency and shorter the wave length
as a wave crosses boundaries between different media like from air to water their speed changes but their frequency remains the same
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Wave theory vs particle theory (compare and contrast):
particle parameters |
the frequency of the wave is proportional to the magnitude of the particles energy
since photons are emitted and absorbed by charged particles, they act as transporters of the EMR energy
unlike waves which are characterized by a velocity, wavelength, and frequency, PARTICLES are known as photons and each has an energy related to the frequency of the wave fiven by an equation
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Atmospheric Effects on Remote Sensing:
Specular vs Diffused reflection |
Specular (mirror like) reflection:
-the EMR incident angle is equal to its angle of reflection from the surface
- the reflecting surgace must be smooth (in the eyes of the EMR
-for example- ice sheets, calm water (lake surface), flate metal surface, airport runways, large solar panels etc
Diffused reflection:
- spreading out or scattering of radiation to all directions depending on surface roughness and orientation
-example- rough surfaces, forest canopies, fresh snow, sand (dunes), clouds, urban buildup, grassland, golf courses.
*most man made objects and water surfaces have reflectance in between these two extremes
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Atmospheric Effects on Remote Sensing:
Scattering effects
1. Rayleigh |
-scatter types: air molecules and very small particles suspended in the air
-scatters diameter- much smaller than the (upside down Y) of the EMR being scattered
-scattering process: involves re radiation by atoms
-it is impossible to predict the direction in which atom will emit a photon
-rayleigh scattering is most obvious in a clear day with few water vapor or dust in the air
- the sky appears blue because scattering of blue light in the visible spectrum is the greatest
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Atmospheric Effects on Remote Sensing:
Scattering effects
2. Mie Scattering |
-scatter types: mainly spherical particles int he atmosphere
scatter diameter: about the same as the (upside down Y) of visible spectrum of EMR
-example: water vapor, dust, smoke, or particles with diameter rangfes from a few micron to a few 10th of a micron
-while rayleigh occurs up to 30,000ft elevation, MIE scattering often happens in lower atmosphere
In a polluted with dust and smoke in the air, Mie scattering may exceed rayleigh scattering, resulting in a redish looking sky |
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Atmospheric Effects on Remote Sensing:
Scattering effects
3. Non selective scattering |
scatter types: mainly large particle in the air
scatter diameter: several times larger than (upside down Y) of the EMR being scattered
example: water droplets (in clouds) scatter all λ spectrum evenly which gives clouds and fog white appearance
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Major atmospheric Absorption agents |
-O2- molecular oxygen |
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Meteorological satellites:
TIROS |
(Television and infrared observation satellite)
the granddaddy of the current global operational meteor satellite system in the US for the past 20 years
launched in 1960
payload: -TV Camera with 3 angles -IR scanner for later missions -Earth radiation and budget instrument for later missions
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Meteorological satellites:
Tiros-N (NOAA) series |
3rd generation TIROS
operational since 1978
Tiros-N sensor instruments:
A.advanced very high resolution radiometer (AVHRR)
B. Tiros operational vertical sounder (TOVS)
C. Data collection and platform location system (DCS)
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Meteorological satellites:
GOES satellites |
Geostationary Operational Environmental Satellite.
sensor systems on board the GOES: - new and improved sensors VAS (visible IR spin-scan radiometer atmospheric sounder)
-build by hughes aircraft
-an advanced version of the VISSR developed for the worldwide geostationary meteorological satellite
VAS retains the VISSR dual ban imaging function
3 VAS operational modes: 1. VISSR cloud mapping mode 3. Multi spectral imaging provided mornal VSSR cloud mappiing function +2 more spectral band data at 13.8 km resolution 3. dwell sounding- up to 12 spectral filters covering the range at the IR region |
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Landsat Program:
TM |
Thematic Mapper
designed to have spatial and spectral resolution of image data
cross-track (185km) line scanning using an oscillating scan mirror and array of 16 detectors - with the exception of band 6 which has only 4 detectors
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Landsat Program:
ETM+ |
Enhanced Thermatic Mapper plus
instrument, produced under NASA contract with Raytheon in Santa Batrbara CA
ETM+ instrument is an eight-band multispectral scanning rediometer capable of providing high-resolution imaging information of the earths surface.
ETM+ will produce approximatley 3.8 gigabits od data for each scene, which is roughly equivelant to nearly 15 sets of encyclopedias
When the SLC is in off mode the ETM+ still acquires approximatley 75% of the data for any given scene, the gaps in the data form alternating wedges that increase in width from the center to the edge of a scene
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SPOT program:
SPOT |
Satellite Pour l'Observation de la Terre
PROGRAM BACKROUND:
This satellite observation system was designed in france and developed with the participation of sweden and belgium in the 1980's
the system was launched and operated by the french space agency CNES
the system comprises a series of spacecrafts plus ground facilities for satellite control and programming, image production and distribution
THE SPOT ORBIT:
quasi polar sun synchronous and circular
altitude- around 822km
sun synchronized at 10:30am at descending mode
cycle (phased) 26 days
The spot payload:
employs the concept of twin-vertical viewing configuration-spacecrafts ground track bisexts the swath imaged by 2 seprate imagin instruments that care called "high resolution visible imaging instruments"
each one of these covers 60 km wide ground strip
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SPOT program:
HRV |
High resolution (10m and 20m)
compatible with the preparation of topological maps at 1/100,000 scale to the required geometric accuracy
also compatible with thematic maps at scales as large as 1/25000
give rise to a concept of an observable corridor extending 850 km for nadir imagery and 80km for extreme oblique imagery
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SPOT Program:
Vegetation monitoring instrument (VMI) |
spatial resolution- 1km VMI0 - .45-.52um (blue) VMI2 - .61-.68um (red) VMI3 - .78-.89um (near-IR) VMI4 - 1.58-1.75um (mid-IR)
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