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GIS > GIS Section 5.2 > Flashcards

GIS Section 5.2 Flashcards

1
Q

What is remote sensing?

A

the science/art of acquiring information about an object (ex earth’s surface)

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2
Q

What data model does remote sensing use?

A

raster

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3
Q

What is RADAR?

A

Radio Detection and Ranging

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4
Q

What are the seven elements of remote sensing?

A
  • Energy source (illumination)
  • Radiation and the atmosphere
  • interaction with the target
  • recording of energy by sensor
  • transmission/reception/processing
  • interpretation/analysis
  • application
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5
Q

What regions of the EM spectrum are used in remote sensing?

A
  • visible
  • infrared
  • microwave (RADAR)
  • ultraviolet, visible, near infrared (LiDAR)
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6
Q

What visible colour has a shorter wavelength?

A

violet

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7
Q

What EM range is infrared?

A

0.7-100micrometers

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8
Q

what is infrared light useful for detecting?

A
  • chlorophyll activity (plants)
  • emitted/thermal IM (temperature
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9
Q

What EM range are microwaves in? (RADAR)

A

1micrometer to 1m

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10
Q

What is RADARSAT?

A

Canada’s instrument to detect changes, especially in far north

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11
Q

Does cloud cover prevent RADAR sensing?

A

Nope! RADAR penetrates cloud cover

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12
Q

What 3 forms of interaction can take place when energy hits a target?

A
  • absorption
  • transmission
  • reflection
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13
Q

Why does water look blue?

A

stronger reflectance of non-blue colours

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14
Q

What can easily be confused with shallow water?

A

water with lots of sediment

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15
Q

How do we ensure constant light conditions in satellite images?

A

at a given latitude, the sun will be in the same position in the sky during the same season
- ie. imaging is ‘sun-synchronous’ and covers each area at a constant local ‘sun time’

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16
Q

How has remote sensing evolved recently?

A

moving from analog to digital

17
Q

how can a satellite image be displayed?

A
  • pixels
  • each pixel represents radiation/brightness with a digital number
18
Q

How does georeferencing work?

A

-Ground Control Points
- match GCPs to known locations

19
Q

What five categories of image processing are most common?

A
  • Pre-processing
  • Image enhancement
  • image transformation
  • image classification
  • analysis of special feature/data integration
20
Q

What is pre-processing in image analysis?

A
  • radiometric corrections: correct for sensor irregularities and unwanted noise
  • geometric corrections: correcting for distortions due to sensor-earth geometry, conversion to coordinates
21
Q

What is image enhancement in image analysis?

A

operations to improve appearance of imagery for visual interpretation

22
Q

What are the three operations in image enhancement (for image analysis)?

A
  • contrast stretching: increase tonal distinction
  • spatial filtering: to enhance specific spatial patterns (filter)
  • atmospheric corrections
23
Q

What is contrast stretching?

A

changing digital values to use more available visual range

24
Q

What are common forms of noise in imagery?

A
  • striping/banding, or dropped lines
25
Q

What is spatial filtering in imagery?

A

used to enhance the appearance of an image
- usually by using math calculation on a window of pixels

26
Q

What does a low-pass filter do?

A

emphasize larger homogenous area
- smooth an image’s appearance

27
Q

What do high-pass filters do?

A

sharpen the image
- often apply a low-pass filter and subtract results from original

28
Q

What is image transformation?

A

generates new images to highlight particular features/properties of interest
- usually image subtraction (cutout image)

29
Q

What is digital image classification?

A

automated process of identifying homogenous groups of pixels
- objective to assign all pixels to particular class/theme

30
Q

What types of image classification are there?

A
  • supervised: analyst identifies some homogenous areas, used as training data
  • unsupervised
31
Q

What is it called when data from different sensors are merged/integrated?

A

multisensor data fusion
- integrate ancillary(supplementary) data - ex image draped over elevation model

32
Q

When was landsat 9 launched?

A

sep 27, 2021
- simultaneously image 4 visible spectrum bands, 1 near IR, 3 shortwave IR, one panchromatic band

GIS (9 decks)

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