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Remote Sensing ConceptsRemote Sensing Concepts

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What is Remote Sensing?What is Remote Sensing?

"Remote sensing is the science (and to some"Remote sensing is the science (and to some

extent, art) of acquiring information about theextent, art) of acquiring information about theEarth's surface without actually being inEarth's surface without actually being incontact with it. This is done by sensing andcontact with it. This is done by sensing andrecording reflected or emitted energy andrecording reflected or emitted energy andprocessing, analyzing, and applying thatprocessing, analyzing, and applying thatinformation."information."

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Basics

Basics

EM spectrum:EM spectrum:

reflectedreflected

emittedemitted

detectiondetection

filmfilm

sensorsensor atmospheric attenuationatmospheric attenuation

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1.Energy Source or Illumination (A)

2. Radiation and the Atmosphere (B)

3. Interaction with the Target (C)

4. Recording ofEnergy by the Sensor (D)

5. Transmission, Reception,

and Processing (E)

6. Interpretation and Analysis (F)

7. Application (G)

Process involves in Remote sensing

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Q = Amount of energy held by a photon

h = Plancks constant (6.626x10^-34 js)

V = frequency (Hz)

C = 3x10^8 m/s

= wavelength (m)

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Recording typeRecording type analog (film)analog (film)

must retrieve filmmust retrieve film

resolution based on film typeresolution based on film type

digitaldigital

easier to retrieve dataeasier to retrieve data

resolution based on sensors/unit arearesolution based on sensors/unit area

RASTER DATARASTER DATA

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Sea Temperature(NOAA AVHRR)

Sea Surface height

Relative to ocean geoid

(Spaceborne radar)

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Ocean and Land Biomass (Orbview-3)

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System classificationsSystem classifications

Passive systemsPassive systems

use existing source ofEM illuminationuse existing source ofEM illumination

Active systemsActive systems

provide source ofEM illuminationprovide source ofEM illumination

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PlatformsPlatforms

airplaneairplane

low & high altitudelow & high altitude

high resolutionhigh resolution

large scalelarge scale

satellitesatellite

various altitudesvarious altitudes

low to high resolutionlow to high resolution small to large scalesmall to large scale

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I

maging characteristicsI

maging characteristics spatial resolutionspatial resolution

most important characteristicmost important characteristic

basisbasis lenslens

film or sensorfilm or sensor

ground resolutionground resolution

spatial resolutionspatial resolution

scalescale

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Imaging characteristicsImaging characteristics

spectral resolutionspectral resolution

EM wavelengths to which a system is sensitiveEM wavelengths to which a system is sensitive

componentscomponents

number of bands (more is better)number of bands (more is better)

width of bands (narrow is better)width of bands (narrow is better)

radiometricradiometric

differences between steps in exposuredifferences between steps in exposure

contrastcontrast

temporal (daily, monthly, yearly, etc.)temporal (daily, monthly, yearly, etc.)

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Selecting image characteristicsSelecting image characteristics

appropriate specificationsappropriate specifications

ground resolutionground resolution

bands & widthsbands & widths

spectral resolutionspectral resolution

determinedetermine

what youwhat you needneed to observeto observe

what you might want in the futurewhat you might want in the future

what you can affordwhat you can afford

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PhotogrammetryPhotogrammetry obtaining reliable measurements fromobtaining reliable measurements from

imagesimages

sciencescience artart

scalescale -- based on:based on:

focal lengthfocal length

height of planeheight of plane

average terrain elevationaverage terrain elevation

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PhotogrammetryPhotogrammetry

satellitesatellite

all types of imagesall types of images

advantagesadvantages

wider coveragewider coverage

tilttilt--freefree

little relief displacementlittle relief displacement

examplesexamples

Landsat TM is 30m, SPOT is 20mLandsat TM is 30m, SPOT is 20m

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Pakistan image (NOAA)

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Pakistan images (Landsat ETM)

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35

36

37

38

39

40

41

42

43

147

148149150151152

153154

155156157

TrichMir Hunza Khunjrab

Peshawar Gilgit Skardu

Bannu Rawalpindi Shakargarh

Quetta Multan Lahore

Zahidan Dalbandin Kalat Bahawalpur Bahawalnagar

Mand Panjgur Sukkur Gotki

Gawadar Turbat Karachi MirpurKhas

Sir Creek

Path

Rows

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EndingEnding