remotely-sensed datasets

Question 1

two types of scanners

Answer 1

across track and along-track

Question 2

aka across track

Answer 2

whiskbroom

Question 3

aka along track

Answer 3

pushbroom

Question 4

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

Answer 4

rotating/oscilliating mirror

Question 5

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

Answer 5

along scan lines at right angles to flight line

Question 6

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

Answer 6

90 to 120 degrees

Question 7

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

Answer 7

incoming energy is separated into several components, sensed independently

Question 8

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

Answer 8

IFOV

Question 9

what does IFOV mean

Answer 9

instantaneous field of view

Question 10

what the scanner sees

Answer 10

IFOV

Question 11

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

Answer 11

D = H’ B

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

Question 12

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

Answer 12

dwell time

Question 13

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

Answer 13

signal to noise ratio

Question 14

ground resolution element or ground resolution D

Answer 14

spatial resolution

Question 15

the ability to discriminate very slight energy differences

Answer 15

radiometric resolution

Question 16

ability to discriminate fine spectral differences

Answer 16

spectral resolution

Question 17

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

Answer 17

F. not necessarily

Question 18

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

Answer 18

ground resolution distance

Question 19

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

Answer 19

along-track scanners (pushbroom)

Question 20

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

Answer 20

there is no mirror

Question 21

describe the detectors in along-track scanners (pushbroom)

Answer 21

they are in a linear array

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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

Question 24

what are the advantages of along-track scanners

Answer 24

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

Question 25

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

Answer 25

- need more calibrations - limited spectral sensitivity of commercial detectors

Question 26

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

Answer 26

gamma-ray spectrometer

Question 27

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

Answer 27

none

Question 28

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

Answer 28

- multispectral scanner - imaging spectrometer - aerial camera - video camera

Question 29

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

Answer 29

none

Question 30

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

Answer 30

thermal scanner

Question 31

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

Answer 31

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

Question 32

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

Answer 32

passive microwave radiometer

Question 33

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

Answer 33

- radar altimeter - imaging radar

Question 34

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

Answer 34

multispectral images

Question 35

when was the first Landsat satellite launced

Answer 35

1972

Question 36

uses of multispectral images

Answer 36

landcover, vegetation, surface mineralogy, surface water mapping

Question 37

5 example of operational multispectral systems/imagery

Answer 37

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)

Question 38

oldest civic earth observation program

Answer 38

Landsat-7

Question 39

first program that released processed data

Answer 39

Terra ASTER

Question 40

what governments are in charge of SPOT-5

Answer 40

french, swedish, belgian governments

Question 41

first commercial high resolution satellite

Answer 41

Ikonos