Unit 8

Question 1

How is hyperspectral remote sensing different from multispectral?

Answer 1

It has 100s of bands that range spectral resolutions. Can estimate the relative abundance of certain features not just their presence or absence.

Question 2

What is the benefit of imaging spectroscopy

Answer 2

Can use the full spectrum for analysis giving higher resolutions
= determine vegetation health, water content, types of vegetation etc.

Question 3

How does a spectral sample from imaging spectroscopy differ from multispectral such as landsat

Answer 3

Instead of inferring the spectral signature from about 5 bands per pixel we have contiguous spectral bands giving a more accurate view of the signature

Question 4

Where does the best spectroscopy occur currently?

Answer 4

Airborne, but increasing interest in spaceborne

Question 5

Why is imaging spectroscopy area-based?

Answer 5

Since it flies over numerous targets there is gridded data that allow for formation of images based on the spectral bands

Question 6

What are examples of airborne imaging spectrometers?

Answer 6

AVIRIS, AVIRIS-NG, CASI/SASI

Question 7

How can we use a library of vegetation spectra?

Answer 7

TO map vegetation types and conditions

Question 8

What are examples of space borne imaging spectrometers?

Answer 8

Hyperion, Hyspiri, ENMAP

Question 9

What is the challenge of imaging spectroscopy and being area-based?

Answer 9

Have to tease out individual objects from the mixed pixels (spectral mixing) through unmixing methods

Question 10

What is linear spectral unmixing?

Answer 10

Using information to determine the fraction or percentage of each feature from known/expected spectral signatures that they have

Question 11

What is an endmember?

Answer 11

A pixel that is assumed to have a pure spectral signature for a given land cover class (Ie. open water)

Question 12

What is a common method of unmixing in land use/land cover studies?

Answer 12

Sub-pixel fractions: applied to optical multi-spectral imagery to derive fractions of specific land cover types

Question 13

What radiation does thermal remote sensing use?

Answer 13

emitted longwave radiation from emitted the earth’s surface (terrestrial)

Question 14

What are the major uses of thermal remote sensing?

Answer 14

To monitor surface temp changes (dirunal, seaonal, interannual) + the earth’s energy budget

Question 15

the internal true temperature of an object from the molecular vibrations

Answer 15

Kinetic temperature

Question 16

define radiant temperature

Answer 16

result of emitted energy from an object also called the apparent or brightness temperature

Question 17

How does wein’s displacement law relate to thermal remote sensing?

Answer 17

All objects emit EM energy and the amount/wavelength is based on the temperature of the object. Hotter objects have smaller wavelengths (inverse relationship).

Therefore we can use this to distinguish features in thermal remote sensing

Question 18

What is a blackbody?

Answer 18

A theoretical object that is a perfect emitter and absorbs all energy = does not reflect anything

Question 19

What happens to emissivity if the radiant temperature is lower than the actual kinetic temperature of an object?

Answer 19

The emissivity will be low

Question 20

What example increases the emissivity?

Answer 20

Water content

Question 21

Are most thermal sensors imaging sensors?

Answer 21

Yes, in comparison LIDAR is not

Question 22

What are some examples of thermal imaging sensor missions?

Answer 22

Landsat, MODIS, ASTER, GOES, ECOSTRESS

Question 23

How can evaporation be used with thermal imaging?

Answer 23

Evaporation causes a slight decrease in temperature so we can infer water stress