Chapter 1

Question 1

• Define Remote Sensing

Answer 1

Collection of information about an object or system without coming into direct physical contact with it. That information is nearly always carried by electromagnetic radiation (EMR).

Question 2

What sort of measurements in Remote Sensing (laundry list)

Answer 2

Measuring force fields, EMR, or acoustic energy employing cameras, radiometers and scanners, lasers, radio frequency receivers, radar systems, sonar, thermal devices, seismographs, magnetometers, gravimeters, scintillometers, and other instruments

Question 3

Seven reasons we do remote sensing?

Answer 3

Unobtrusive.
Automated.
Useful for extreme conditions.
Combination of spatial and temporal coverage.
Extends our senses (beyond visible light)
Near real-time
No political boundary?

Question 4

Spatial coverage

Answer 4

Global, regional, local

Question 5

Seven Applications of remote sensing

Answer 5

• Meteorology
• Oceanography
• Glaciology Sea Ice Research
• Geology
• Agriculture
• Hydrology
• Disaster control

Question 6

Meteorlogy uses of remote sensing

Answer 6

– Profiling atmospheric temperatures and water vapor
– Measuring wind speed
– Watching evolution and trajectories of storms

Question 7

Oceanography uses of remote sensing

Answer 7

– Measuring sea surface temperatures and salinity – Mapping of ocean currents
– Measuring sea level rise and variability

Question 8

Glaciology uses of remote sensing

Answer 8

– Mapping motion of glaciers and ice sheets
– Monitoring ice melt
– Determining navigability of polar oceans

Question 9

Geology uses of remote sensing

Answer 9

– Identification of rock types

– Location of geological faults and anomalies

Question 10

Agriculture uses of remote sensing

Answer 10

– Monitoring extent and type of vegetation
– Mapping soil types
– Estimating vegetation biomass

Question 11

Hydrology uses of remote sensing

Answer 11

– Assessing water resources
– Forecasting melt water runoff from snow
– Determining soil moisture

Question 12

Diaster control uses of remote sensing

Answer 12

– Warnings of sand and dust storms
– Flooding
– Monitoring of pollution

Question 13

Analog benefits (4)

Answer 13

– Medium is film
Benefits
• Easy to view
• High spatial resolution
• Sometimes cost-effective 
• Compact

Question 14

Analog drawbacks (4)

Answer 14

– Medium is film
Drawbacks
• Difficult to transmit remotely
• Difficult to edit after acquisition
• Limited response to light (visible and near infrared wavelengths only)
• Degradation over time can limit archive capabilities

Question 15

Digital benefits (4)

Answer 15

• Wide variety of detectors
     – Electromagnetic and other types 
     – Large amplitude range
• Data easily transmitted remotely
• Data easily edited/manipulated/enhanced after acquisition 
• Long-term archive

Question 16

Digital drawbacks (3)

Answer 16

• Storage requirements can be large
• Reduced spatial resolution in many cases
• Requires sophisticated equipment and analysis techniques to use

Question 17

Four types of Remote Sensing Systems

Answer 17

• Active Sensor – illuminates subject from an artificial (on- board) energy source
• Passive sensor – uses naturally emitted radiation from the sun or the object being observed
• Imaging sensor – creates a “picture” by scanning across a linear array of detectors while the array moves through space
• Non-imaging sensors – measures along a transect or at a point

Question 18

5 characters for Summarizing Remote Sensing Systems

Answer 18

• Platform:Ground,airborne,satellite
• Media: digital or analog
• Illumination: passive or active
• Detector configuration: imaging, single-point, transect or sounding
• Spectralrange:visible,infrared,microwave,etc.

Question 19

Conduction

Answer 19

transfer of kinetic energy between atoms or

molecules

Question 20

Convection

Answer 20

transfer of kinetic energy by physically moving mass that contains that energy

Question 21

Radiation

Answer 21

propagation via waves or particles through a vacuum or medium

Question 22

Sources of EMR (active and passive)

Answer 22

– Sun and Earth are both passive sources of EM radiation

– Lasers and radars are active sources of EM radiation

Question 23

How is EMR generated?

Answer 23

– Kinetic: motion of atoms or molecules producing heat (thermal)
– Electrical: generation of electric fields radio frequency
– Magnetic: polarization of charged atoms (microwave)
– Chemical: molecular excitation (visible)

Question 24

Electromagnetic waves (basic definition)

Answer 24

Energy travels in waves described by
– Wavelength λ ( of frequency f/v), crest to crest
– Amplitude (a), crest to midline

Question 25

Visible wavelength range

Answer 25

λ = 390 nm – 750 nm (3.9 - 7.5 x10^-7 m)
Blue:.4-.5 μm
Green: .5-.6 μm
Red: .6 - .7 μm

Question 26

Most common remote sensing data types (EMR)

Answer 26

visible, infrared, thermal, and microwave

• Sun (most impt)
– Reflected solar energy 0.3 – 2.5 (3) μm
• Earth
– > 6 μm for self-emitted energy

μm = 1x 10^-6 m

Question 27

Applications for Remote sensing (Summary)

Answer 27

• Remotely gathering information carried by EMR
• Quantitative analysis of digital information
– Image interpretation from hard copy is history
– Additional computational and analytical skills are required
• Global change issues can be addressed
• Highly interdisciplinary

Question 28

Microwave wavelength range

Answer 28

λ = 1 mm – 1 m ( 1 x 10^-7 to 1 x 10^-9 nm))

Question 29

Infrared wavelength range

Answer 29

λ = .75 - 30 μm (1,000 nm – 30,000 nm)

near IR = .75 to 1.3 μm
mid (short-wave) = 1.3 - 3 μm
thermal IR = two bands 3 - 5 μm and 8-14 μm
far IR = 3 - 30 μm

Question 30

Collateral data

Answer 30

Aka ancillary data

Digital elevation models (DEMs), maps, political boundary files, population stats, etc. often in GIS

Question 30

Formula for relationship between wavelength and freq

Answer 30

c = λv

3.0 x 10^8 m/s = λ (in μm or nm) x v (in Hz, or 1/s)

Question 31

Add spectral ranges

Answer 31

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