Concepts foundations of remote sensing
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Concepts & Foundations of Remote Sensing. L&K pages 1 – 12 GEO 410 Dr.Garver. Powerpoints : 3_energy.ppt & 4_LK_pg1-12.ppt Readings: Sections 1.1 to 1.4 of online text & LK1 reading Concepts/Calculations: EMR, EMS Wavelength vs. frequency Visible, IR (near IR, Thermal IR)

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Concepts & Foundations of Remote Sensing

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Concepts foundations of remote sensing

Concepts & Foundations of Remote Sensing

L&K pages 1 – 12

GEO 410

Dr.Garver


Quiz 1

  • Powerpoints: 3_energy.ppt & 4_LK_pg1-12.ppt

  • Readings: Sections 1.1 to 1.4 of online text & LK1 reading

  • Concepts/Calculations:

    • EMR, EMS

      • Wavelength vs. frequency

      • Visible, IR (near IR, Thermal IR)

      • Reflected vs. emitted

    • SB Law, Weins Law – Sun/Earth example

    • How energy interacts with atmosphere (absorption, scattering (3 types), reflection)

      • Albedo

    • Atm. Windows, main gases that absorb

Quiz 1


1 1 introduction

  • Defines r.s.

  • Electromagnetic energy sensors on airborne and spaceborne platforms

  • Sensors acquire data on the way earth/atm features reflect and emit EMR.

1.1 Introduction


Figure 1

  • Electromagnetic r.s. of earth resources

  • Illustrates generalized process and elements involved in r.s.

    • Data acquisition (a to f) – GEO 410

      • a – d <= energy/atm

      • e - f <= sensors/data

    • Data analysis (g to h) – GEO 420

      • interpretation/analysis/output/GIS/end users

Figure 1


Remainder of chapter basic principles of r s

  • Fundamentals of EMR

  • Interactions w/atm

  • Interactions with surface

  • Ideal r.s. system

    • Limitations

  • Close relationship between r.s., GPS and GIS

Remainder of chapter – Basic principles of r.s.


1 2 energy sources radiation principles

  • EM spectrum

  • C = vl(1.1)

  • Wave theory - EM waves obey this eqn

  • Categorize EMR by wavelength along spectrum

1.2 Energy Sources & Radiation Principles


1 2 energy sources radiation principles1

  • VISIBLE = 0.4 – 0.7

    • Blue = 0.4 - mm 0.5 mm

    • Green= 0.5 - 0.6 mm

    • Red= 0.6 - 0.7 mm

  • IR – only thermal IR is related to heat

  • Wave theory C = vleqn 1.1

  • Particle Theory Q = hv eqn 1.2

    • Discrete photons

  • Can relate these two models:

    • Q= hc/leqn 1.3

1.2 Energy Sources & Radiation Principles


1 2 energy sources radiation principles2

  • Energy is inversely proportional to wavelength.

    • Longer wavelength = less energy

    • Implication for r.s.- microwave harder to detect than VIS or IR.

    • Systems operating at longer wavelengths need to view large areas of earth to get a detectable signal.

1.2 Energy Sources & Radiation Principles


Concepts foundations of remote sensing

  • Sun is source of EMR for r. s.

  • But, all matter at T above absolute zero (0 K) emits EMR.

  • So, terrestrial objects are also sources of radiation but at a different wavelength and magnitude.

    • SB Law (1.4)

    • Energy emitted varies as T4


Concepts foundations of remote sensing

  • Blackbody – hypothetical ideal radiator

    • Absorbs and emits all energy equally

  • Dominant wavelength

    • Wein’s law (1.5)

    • Figure 1.4 – spectral distribution of energy

    • Sun vs. Earth

    • Dividing line between reflected and emitted

    • Radar – active not passive (supplies own energy source)

      • Flash on a camera


1 3 energy interactions in atm

  • All radiation detected by sensors passes through some pathlength of atm

  • Scattering – unpredictable - different size particles

  • Absorbers – effective loss of energy, most effective absorbers (water vapor, CO2, O3)

  • Atmospheric windows – wavelengths on which the atm is particularly transmissive.

  • Fig. 1.5

1.3 Energy Interactions in Atm


Concepts foundations of remote sensing

2 Energy Sources Used in R. S.

R. S. is limited to Atmospheric Windows

Common Sensors

Fig. 1.5


Concepts foundations of remote sensing

  • Fig. 1.5

    • Vis range coincides with an atm window

    • Thermal IR bands: 3 - 5 mm and 8 – 14 mm

    • Multispectral scanners – sense simultaneously through multiple narrow wavelength windows through Vis and IR

    • Radar and passive micro: 1mm – 1m window


Concepts foundations of remote sensing

  • Take home message:

  • Interaction and interdependence between primary sources of EMR, atm windows and spectral sensitivity of sensors.

  • Need to consider 1) spectral sensitivity of sensors available,

  • 2) presence/absence of atm windows in the spectral range you are interested in, and

  • 3) the source, magnitude , and spectral composition of the energy available in these ranges.

  • End of section 1.3


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