Final Exam Text Flashcards
remote sensing
the process of collecting information related to the electromagnetic energy reflected or emmited by a target on the ground using a device a considerable distance away from the target on board an aircraft of spacecraft
wavelength & frequency
the distance between the crests of two waves
- think of it like the ocean
- longer wavelength means increased space between crest
- longer wavelength means less frequency
micrometer
nanometer
one-millionth of a meter
one-billionth of a meter
visible light spectrum
0.4-0.7
band
a narrow range of wavelengths that may be measured by remote sensing
infrared
Near Infrared
shortwave infrared
thermal infrared
wavelengths between 0.7 and 100
- 7 and 1.3
- 3-3.0
- 0-14.0
atmospheric windows
those wavlengths of electromagnetic energy in which most of the energy passes through earths atmosphere
Why is there no point to have a sensor measuring wavelengths such as untrviolet because…
they are completley absorbed by the atmosphere, so no reflectant energy to measure
atmospheric window
Rayleigh scattering
scatteering of light caused by atmoshoeric particles smaller than the wavelength being scattered
mie scattering
scattering of light caused by atmospheric particles the same size as the wavelength being scattered
non-selective scattering
scattering of light caused by atmospheric particles larger than the wavelength being scattered
_____ wavlengths are scattered more then _____ wavelengths
shorter, longer
-explains why sky is blue during day, shorter blue wavelengths scattered far more then longer red
transmission
absorption
occures when light passes through a target and interacts with something else after
when light is trapped and held by a target
incident energy
spectral reflectance
total ammount of energy that strikes a surface
-calculated by adding up the ammounts of energy that were transmitted, absorbed, and reflected by a surface
I=R+A+T
the percentage of the total incident energy that was reflected from that surface
(R/I) x 100
spectral signature
a unique identifier for a particular item, generated by charting the percentage of reflected energy per wavelength against a value for that wavelength
NDVI returns a value between __ and __, the ______ the value the healthier he vegetation.
-1, +1
higher
.low values mean unhealthy vegetation
. very low means nothing is growing at all
. more red energy reflection and low near infrared means unhealthy
spatial resolution
the size of the area on the ground represented by one pixels worth of energy measurment
brightness values
the energy measured at a single pixel according to a predetermined scale;also refered to as digital numbers
8 bit imagery is a digital image that carries a range of brightness values from __ to __
0(black) to 255(white)
multispectral imagery
remotely sensed imagery created from the bands collected by a sensor capable of sensing several bands of energy
hyperspectral imagery
remotely sensed imagery created from the bands collected by a sensor capacble of sensing hhundreds of bands at once