quiz 1 Flashcards
what is continuity in remote sensing
field based observations are only discrete “points in space. Remote sensing allows for spatially continuous data.
what three things does remote sensing provide
1.)continuity
2.)scale
3.)visibility
what is scale in remote sensing
scale is the relationship between reality and what is actually displayed
Explain active vs passive remote sensing
-active: active is when the remote sensing device emits electromagnetic radiation
-passive: passive is when the sun or other objects send out the electromagnetic radiation
true or false: energy can be emitted, transmitted, reflected, or absorbed
true
what is electromagnetic radiation
rediation that propagates as a wave of electric and magnetic field perpendicular to each other
what is particle radiation
radiation of energy by fast moving subatomic particles
what is acoustic radiation
radiation that takes the form of mechanical waves
gravitational radiation
takes the form of gravitational waves
what is wavelength
wavelength is the distance between peaks
what is frequency
frequency is how often you see a peak on the same side
what is the relationship between frequency and wavelenght?
inverse relationship. Long wave length means lower frequency
what are wave and quanta in electromagnetic radiation, and is electromagnetic radiation made up of both?
yes electromagnetic radiation is made of both waves and quanta.
waves are continuous and quanta are discrete particles
is energy inversely related to wavelength?
yes the longer the wavelength the less energy
what is the stefen-boltzman law
this law defines the relationship between temperature and energy emited
true or false: matter at temps above absolute zero continuously emit electromagnetic radiation
true
what is a black body
a blackbody is a hypothetical ideal radiator that totally absorbs and reemits all energy incident upon it
does temperature impact wavelength?
yes it does
what is wins displacement law
gives you the wavelength of an object based on its heat. You have to convert from celsius to kelvin by adding 273.15. The formula is A/T where A is a constant 2897.8 and T is abosulte temp in kelvin
what variables affect radiation going through the atmosphere
-difference in path length
-magnitudde of energy being senses
-atmosphere condition
-wavelength involved
what are the two ways atmosphere interacts with radiation
scattering and absorption
what is rayleigh scattering
spreading radiation everywhere around a particle because the wavelengths are larger than the particle
what is mie scattering
mie scattering the wavelengths are about the size of the particles and the vast majority of scattering is in the direction of the wave
what is non selective scattering
the wavelength is smaller than the large particles and scattering is in random directions
what are the three fundemental interactions energy has with the earth
transmitted energy, reflected energy, and absorbed energy
what is the energy balance equation
incident energy(EI) = reflected energy(ER) + transmitted energy(ET) +absorbed energy (EA)
-incident energy is the energy coming in
what is spectral reflectance
the portion of incident energy that is reflected
what is a spectral reflectance curve?
an average reflectance value compiled from large number of features
what is a spectral signature
its the spectral response which allows the assessment of an object. these come from spectral reflectance curves
what are the spatial and temporal effects influencing spectral signature
1.)temporal effects: factors change the spectral signature of an object over time
2.)spatial effects: factors that change the spectral signature of a feature at a given point in time at different locations
what is atmospheric correction
difference between two “signatures” caused by atmospheric scattering and absorption in the instrument
what is geometric impact on spectral signature
geometry impacts the amount of energy reflected by an object
what is specular reflectors
are flat surfaces that manifest like a mirror
what are diffuse reflectors
reflectors are rough surfaces that reflect uniformly in all directions
for remote sensing do we want diffuse of specular reflectors
we want diffuse
describe spectral bands
every sensor records certain energy wave lengths that can then be chopped into even finer portions of the wavelength known as bands
what is a digital number
a digital number is a value assigned to each pixel that represnets energy or the color is has
what are the 3 ways images are stored
1.) band sequential
2.)band interlead by line
3.) band interlead by pixel
what is DSM
digital surface model which describes the elevation of uppermost surfaces
what is DTM
digital terrain model which is elevation of bare land
what is DEM
digital elevation model which is a general description of elevation
what is the canopy height model and how do you get canopy heights
you subtract DSM from DTM to get CHM which is height of trees
what are the 3 ways reference data might be used
1.) to aid in analysis and interpretation of data
2.)to calibrate a sensor
3.)to verify data information
what are the 4 distortions of map projections
-shape
-size
-distance
-bearing
when making a map projection how many out of the 4 distortions are you able to choose
you can only ever not have 2 aspects distorted out of the 4
what are the basic elements of image interpretation
-shape
-size
-pattern
-tone
-texture
-shadow
-site
what are the 4 types of resolution
1.)temporal
2.)spatial
3.)spectral
4.)radiometric
describe temporal resolution
how often the same area is observed to detect changes over time
describe spatial resolution
spatial resolution is the limit on how small an object can be on earths surface and still be delineated from its surroundings
describe spectral resolution
sensors ability to distinguish features based on spectral properties
-depends on the number of spectral bands and wave lengths
describe radiometric resolution
sensors ability to differentiate among brightness
true of false: spatial resolution is inversely related to the number or wavelengths (spectral resolution) and the radiometric resolution
true
describe how spatial resolution is a function of sensor size
with a larger pixel you get worse resolutions therefore smaller sensors have better resolution but a smaller area is seen. because these sensors are small they also capture little energy and might not see anything
what are the 3 types of projections
1.)cylindrical
2.)conical
3.)planar
what is gnomic, orthographic and stereographic
these are all view points on earth
1.)othorgraphic:lines point down towards infinity and are parallel, its the best in theory
2.)gnomonic is a view point at earths center
3.)stereogrphic is a view point at earths surface
