remotely-sensed datasets Flashcards

1
Q

two types of scanners

A

across track and along-track

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2
Q

aka across track

A

whiskbroom

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3
Q

aka along track

A

pushbroom

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4
Q

what mirror is used by across-track scanner (whiskbroom)

A

rotating/oscilliating mirror

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5
Q

how does the across-track scanner (whiskbroom) scan the terrain

A

along scan lines at right angles to flight line

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6
Q

what is the typical angle of arc below the aircraft for data collection in across-track scanner (whiskbroom)

A

90 to 120 degrees

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7
Q

describe how energy is processed in across-track scanner (whiskbroom)

A

incoming energy is separated into several components, sensed independently

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8
Q

cone of angle within which incident energy is focused on the detector in across-track scanner (whiskbroom)

A

IFOV

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9
Q

what does IFOV mean

A

instantaneous field of view

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10
Q

what the scanner sees

A

IFOV

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11
Q

equation for diameter of circular ground area viewed in across-track scanner (whiskbroom)

A

D = H’ B

D = diameter of circular ground area
H’ = flying height
B = IFOV in radians

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12
Q

residence time of measurement for across-track scanner (whiskbroom)

A

dwell time

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13
Q

relationship between signal coming from the target to extraneous/background electronic noise in across-track scanner (whiskbroom)

A

signal to noise ratio

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14
Q

ground resolution element or ground resolution D

A

spatial resolution

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15
Q

the ability to discriminate very slight energy differences

A

radiometric resolution

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16
Q

ability to discriminate fine spectral differences

A

spectral resolution

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17
Q

T or F. the ground distance between adjacent sampling points in a digital scanner image needs to be exactly equal to the dimensions of the IFOV projected onto the ground

A

F. not necessarily

18
Q

ground distance between 2 lines that can be distinguished in a photograph

A

ground resolution distance

19
Q

type of scanner that record multipectral image data along a swath beneath an aircraft

A

along-track scanners (pushbroom)

20
Q

describe the mirror used in along-track scanners (pushbroom)

A

there is no mirror

21
Q

describe the detectors in along-track scanners (pushbroom)

A

they are in a linear array

22
Q

describe the size of the ground resolution cell in along-track scanners (pushbroom)

A

it is determined by the IFOV of a single detector projected onto the ground

23
Q

how is the ground sampling distance set in along-track scanners (pushbroom)

A

it is set by the sampling interval deltaT used for A to D signal conversion

24
Q

what are the advantages of along-track scanners

A
  • longer dwell time
  • robust geometric integrity
  • smaller in size and weight
  • higher reliability
  • longer life expectancy
25
Q

what are the disadvantages of along-track scanners (pushbroom)

A
  • need more calibrations
  • limited spectral sensitivity of commercial detectors
26
Q

what are the passive sensors used to capture multispectral images under gamma domain

A

gamma-ray spectrometer

27
Q

what are the active sensors used to capture multispectral images under gamma domain

A

none

28
Q

what are the passive sensors used to capture multispectral images under visible domain

A
  • multispectral scanner
  • imaging spectrometer
  • aerial camera
  • video camera
29
Q

what are the active sensors used to capture multispectral images under visible domaint

A

none

30
Q

what are the passive sensors used to capture multispectral images under longer optical domain

A

thermal scanner

31
Q

what are the active sensors used to capture multispectral images under the longer optical domain

A

none, but in between like right after visible is: laser scanner

32
Q

what are the passive sensors used to capture multispectral images under microwave domain

A

passive microwave radiometer

33
Q

what are the active sensors used to capture multispectral images under microwave domain

A
  • radar altimeter
  • imaging radar
34
Q

images whose measurements are made for different ranges of the EM spectrum

A

multispectral images

35
Q

when was the first Landsat satellite launced

A

1972

36
Q

uses of multispectral images

A

landcover, vegetation, surface mineralogy, surface water mapping

37
Q

5 example of operational multispectral systems/imagery

A
  1. NOAA-17: National Oceanic and Atmospheric Administration
  2. Landsat-7 (Land Remote-Sensing Satellite (System))
  3. Terra ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer sensor)
  4. SPOT-5 (Satellite pour l’Observation de la Terre “Satellite for observation of earth”)
  5. Ikonos (from greek word ‘eikon’ or icon)
38
Q

oldest civic earth observation program

A

Landsat-7

39
Q

first program that released processed data

A

Terra ASTER

40
Q

what governments are in charge of SPOT-5

A

french, swedish, belgian governments

41
Q

first commercial high resolution satellite

A

Ikonos