Drive PPT Flashcards
Measures emitted energy; based on measuring EM in the infrared region; 3-5µm (MIR) and 8-14µm (TIR)
thermal remote sensing
the main factor in thermal remote sensing
Surface temperature
T or F: thermal remote sensing cannot be performed during night time
False. it can be performed during night time.
“the radiation maximum shifts to longer wavelengths as temperature decreases” is based on what law
Wien’s Law
T or F: as energy varies. spectral characteristics also varies
True
wavelength at which blackbody radiation curve reaches
maximum
Dominant wavelength
Materials that absorb and radiate only a certain fraction compared to a blackbody
Greybody
radiate only a certain fraction of a blackbody, but this fraction changes with wavelength.
Selective Radiator
The fraction of energy that is radiated by a material compared to a true blackbody
Emissivity
emissivity values are most important and are used to distinguish between ____________
surface geologies
highlight the areas where a surface material of interest is predominant; reduces the influence of differences in surface temperature
band ratio
minimize the common information (i.e. surface temperature) and enhance the visibility of the differences in the bands. Include Principal Component Analysis (PCA) or Decorrelation Stretching, and Rock emissivity mapping
Transformations
absorption bands in thermal infrared are mainly
caused by
silicate minerals (e.g. quartz, feldspar)
T or F: many rock and soil types show distinct
spectra in the thermal infrared.
True
detection and monitoring of small areas with thermal anomalies; related to fires, such as forest fires or underground coal fires, or to volcanic activity, such as lava flows and geothermal fields
Thermal hotspot detection
Imaging spectrometry which typically acquire images in a large number of spectral bands (more than 100).
Hyperspectral imaging
absorption in the wavelength region from 0.4 µm to 2.5 µm is commonly used to determine
mineralogical content of rocks
Processes that cause absorption of electromagnetic radiation occur at a
molecular and atomic level
two types of hyperspectral imaging processes:
electronic and vibrational processes
individual atoms or ions in minerals absorb photons of specific wavelengths, which cause absorptions at certain wavelengths in reflectance spectra; Fe3+ atoms in iron
oxides and hydroxides
Electronic processes
molecular bonds absorb photons, which results in vibration of these molecules; Al-OH bonds in clay minerals, bonds in H2O and OH−in hydrous minerals, and in CO32− in carbonate minerals.
Vibrational processes
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.
Spectral matching algorithms
calculates the spectral similarity between an unknown reflectance spectrum, (consisting of band values ti), and a reference (field or laboratory) reflectance spectrum, (consisting of band values ri), and expresses the spectral similarity of the two in terms of the vector angle, θ, between the two spectra as calculated using all the bands
spectral angle mapper (SAM)
observed as pixel reflectance values result from the spectral mixture of a number of ground classes present at the sensed surface
Spectral unmixing
Mixing is linear if:
- multiple scattering does not occur inside the same material
- no interaction between materials occurs
- the scale of mixing is very large as opposed to the grain size of the materials.
what are the sources contributing to spectral mixing
optical imaging systems, all materials present in the field of view, variable illumination conditions
