hyperspectral images

Question 1

typical number of spectral bands in hyperspectral imaging

Answer 1

more than 100

Question 2

describe bands in hyperspectral imaging

Answer 2

• narrow (less than 10 to 20 nanometers width)
• contiguous (adjacent)

Question 3

implication of hyperspectral imaging bands being narrow and contiguous

Answer 3

enables the extraction of reflectance spectra at pixel scale

Question 4

for hyperspectral imaging, what absorption band is typically used to determine mineralogical content of rocks

Answer 4

0.4 to 2.5 microns

Question 5

what minerals are detected by hyperspectral imaging

Answer 5

phyllo-silicates, carbonates, sulphates, iron oxides and hydroxides

Question 6

two types of process in hyperspectral imaging

Answer 6

electronic processes and vibrational processes

Question 7

individual atoms or ions in minerals absorb photons of specific wavelengths, which cause absorptions at certain wavelengths in reflectance spectra

Answer 7

electronic processes

Question 8

molecular bonds absorb photons, which results in vibration of these molecules

Answer 8

vibrational process

Question 9

example of electronic process involved in hyperspectral imaging

Answer 9

Fe3+ atoms in iron oxides and hydroxides

Question 10

example of vibrational processes that are involved in hyperspectral imaging

Answer 10

Al-OH bonds in clay minerals
bonds in H2O and OH- in hydrous minerals
CO3 2- in carbonate minerals

Question 11

aim at quantifying the statistical or physical relationship between measurements at a pixel scale and field or laboratory spectral responses of target materials of interest.

Answer 11

spectral matching algorithms

Question 12

observed as pixel reflectance values that result from spectral mixture of a number of ground classes present at the sensed surface

Answer 12

spectral unmixing

Question 13

when is spectral unmixing linear

Answer 13

1. no multiple scattering in the same material (no multiple bounces)
2. no interaction between materials (each photons sees only one material)
3. scale of mixing is large compared to grain size of material

Question 14

sources that contribute to spectral mixing

Answer 14

1. optical imaging systems integrate reflected light from each pixel,
2. all materials present in the field of view contribute to the mixed reflectance sensed at a pixel, and
3. variable illumination conditions due to topographic effects result in spectrally mixed signals