1 / 14

Concepts & Foundations of Remote Sensing

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)

taran
Download Presentation

Concepts & Foundations of Remote Sensing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Concepts & Foundations of Remote Sensing L&K pages 1 – 12 GEO 410 Dr.Garver

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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 = vl eqn 1.1 • Particle Theory Q = hv eqn 1.2 • Discrete photons • Can relate these two models: • Q= hc/l eqn 1.3 1.2 Energy Sources & Radiation Principles

  8. 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

  9. 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

  10. 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

  11. 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

  12. 2 Energy Sources Used in R. S. R. S. is limited to Atmospheric Windows Common Sensors Fig. 1.5

  13. 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

  14. 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

More Related