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Remote sensing > RS Fundamentals > Flashcards

RS Fundamentals Flashcards

1
Q

Remote sensing

A

involves the use of instruments or sensors to capture the spectral and spatial relations of objects and materials observable from a distance

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2
Q

Components

A
  • Energy source
  • Radiation and atmosphere
  • Interaction with target (changes nature)
  • Energy recorded by sensor
  • Transmission, reception, processing
  • Interpretation and analysis
  • Application of information
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3
Q

In RS main types of radiation processes are…

A
  • emission
  • reflection
  • absorption
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4
Q

(ENERGY SOURCE) RS focuses on….

A

Measurement and information content of EM radiation

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5
Q

EM spectrum

A

-each interval makes up band or channel by:
colour
descriptive label
specified wavelengths

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6
Q

RS uses range of EM radiations

A

0.1 micrometers - 1m

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7
Q

UV radtiation

A

100-400 nm
Shortest wavelength used
-Induced fluorescence in the visible

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8
Q

Visible

A

0.4-0.7 micrometers
-Only visible wavelengths
(RGB)

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9
Q

Near Infrared

A
  1. 7-1.2 micrometers
    - Just beyond visible
    - Discriminated Green Vegetation well
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10
Q

Mid Infrared

A
  1. 2-8 micrometers

- Between NIR and thermal

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11
Q

Short Wave Infrared

A
  1. 2-3 micrometers
    - Detects solar radiation
    - Good for soil and veg moisture

3-8 micrometers

  • Solar reflected and surface emitted
  • Good for High temp sources
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12
Q

Thermal Infrared

A

8-14 micrometers

-Used to map surface Temp

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13
Q

Microwave

A

Penetrate cloud cover

-Detects Moisture

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14
Q

Passive energy source

A
  • reflected energy from sun

- radiation emitted by objects

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15
Q

Active energy source

A

sensor generates own energy

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16
Q

Atmospheric interactions

A

-Interacts with incoming and outgoing EM radiation
-Gases (N, O, CO2, O3) + particles effects:
absorption
reflection & scattering
transmission

17
Q

Atmospheric absorbers

A

Oxygen - filters UV below 0.1 micrometers
O3 - eliminates UV below 0.3 micrometers
Water vapour - strong absorber ~6 micrometers
CO2 - absorbs in TIR and from 2.5-4.5 micrometers

18
Q

Scattering

A

redirection of EM radiation from original path due to gas or particles in atmosphere
-amount is dependent on wavelength, amount of particles and distance travelled

19
Q

Rayleigh Scattering

A

particle &laquo_space;wavelength
shorter wavelength = more scattering
all directions

20
Q

Mie Scattering

A

particle >= wavelength

still spread out but more in direction of EM travel

21
Q

Non Selective scattering

A

particle > wavelength

dominantly direction of EM travel

22
Q

At surface radiation…

A
  • is absorbed
  • passes through target
  • reflects
23
Q

Spectral response

A
  • signature dependent on degree of reflectance
  • Texture dependent (in comparison to wavelength)
  • smooth = reflection one direction
  • rough = all direction
24
Q

Land cover types do not always coincide with spectral reflectance curves due to variability of….

A
  • solar elevation
  • slope
  • aspect
  • atmosphere
  • obstructions
25
Q

Spectral reflectance signatures

  1. ) snow
  2. ) glacier ice
  3. ) rock
  4. ) water
A
  1. ) snow = high reflectance in visible
  2. ) glacier ice = lower in visible and near IR
  3. ) rock = high absorption
  4. ) water = high absorption
26
Q

Water as target

A

Long wavelength = absorbed
Short wavelength = reflected
suspended sediment = better reflectivity

27
Q

Resolution

A

Ability to discriminate information:

  • spatial
  • spectral
  • radiometric
  • temporal
28
Q

Spatial Resolution

A

Min seperation at which objects appears independent and isolated
-Expressed a pixel size

Eg
MODIS - 1km
SPOT - 20m
IKONOS - 1m

29
Q

When pixel size is smaller (greater spatial resolution)…

A

Pixel is more likely to be homogenous - closer to original value of target

30
Q

Spectral Resolution

A

Number of bands provided by sensor and associated spectral bandwidths

31
Q

Radiometric resolution

A

Indicated sensitivity of a sensor

For digital images the radiometric resolution = range of values coded by sensor

32
Q

Temporal Resolution

A

Observation frequency
- cycle based on certain orbital characteristics and atmospheric conditions

Meteorological : 15-20 min
Landsat 5-7 : 16 days
Radar : 28 days

Remote sensing (3 decks)

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