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48 Cards in this Set
- Front
- Back
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What are the two types of image enhancement?
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Contrast enhancement
Spatial enhancement |
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What does contrast enhancement do?
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increases the contrast between objects and background.
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Give examples of contrast enhancement
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Linear contrast stretch
Histogram equalization |
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define spatial enhancement
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spatial filtering designed to highlight or suppress specific features in an image based on spatial frequency
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spatial frequency=?
high= low= |
image texture
high=rough low=smooth |
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name 2 types of ways filters can be designed using a moving window
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change the formula for calculations
weighting the individual pixels in the filter/window |
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what are the four types of spacial filters
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low pass
high pass edge convolution |
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describe effects of low pass filter
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used to emphasize larger, homogenous landscape, blurs smaller details
smooths appearance |
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describe effects of high pass filter
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opposite of low
sharpens appearance of fine details |
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describe effects of edge filter
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highlights linear features like roads and boundaries
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describe effects of convolution
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a moving kernel with a weighting factor for each pixel
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name two types of image classes
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information class
spectral class |
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define information class
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categories of interest that analyst tries to identify=
land use, land cover |
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define spectral class
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groups of pixels with similar brightness values in different spectral channels of image
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define steps in supervised classification
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identify homogenous representative samples of each information class (training areas)
run classification |
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name two ways analyst selects appropriate training sites
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familiarity with study area
knowledge of actual surface cover types presented in image |
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name 3 types of supervised classification classifiers
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minimum distance to mean classifier
parallelpiped classifier maximum likelihood classifier |
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explain unsupervised classification
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spectral classes are grouped based soley on numerical information of the image
then analyst matches spectral classes to information classes use data clustering algorithms |
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is supervised classification manual or automatic
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manual
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is unsupervised classification manual or automatic
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automatic
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name 4 indications of accuracy assessment
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overall accuracy
producer's accuracy user's accuracy kappa coefficient |
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define overall accuracy
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the percentage of correctly classified pixels
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define producer's accuracy
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measure of accuracy of particular classification scheme
shows percentage of particular ground class was correctly classified |
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define user's accuracy
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measure of reliability of an output map
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define kappa coefficient
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statistical measure of agreement, beyond chance, between two maps (output map and ground-truthed map)
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name three types of advanced sensors
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hyperspectral remote sensing
thermal remote sensing radar remote sensing |
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why use hyperspectral
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many applications that require great details of earth's surface
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why use thermal remote sensing
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detects thermal energy and is useful in detecting temperature of objects on Earth's surface
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why use radar remote sensing
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radar is weather independent and can achieve high resolution
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name 5 applications of hyperspectral sensor
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atmosphere
water resources vegetation: crop identification geology: mineral mapping urban land cover classification-road material, centerline extraction |
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what are main advantages of hyperspectral remote sensing?
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NEED TO FILL IN
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name 2 aspects of thermal remote sensing
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infrared spectrum
thermal sensors |
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name common divisions of infrared energy
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reflected infrared
thermal infrared |
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what type of track is usually used in thermal sensors
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across track sensors
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what time of day can thermal sensors be used
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both day and night
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name 4 things measured by thermal sensors
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surface temperature (land and water)
atmospheric sounding (temperature and humidity) radiation balance emissivity |
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name wavelengths in reflected infrared
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near-infrared
short-wavelength mid-wavelength |
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name wavelengths in thermal infrared
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long wavelength
far infrared |
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how does spatial resolution of thermal sensors compare to visible bands
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spatial resolution is lower
IE. landsat: band 7=60 m band 1=30 |
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name 4 satellites with infrared capability
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trmm
landsat-7 eos terra eos aura |
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name 6 hyperspectral sensors
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hyperion
hydice AISA CASI AVIRIS ASD (analytical spectral device) |
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name 5 applications of thermal imagery
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military investigation
forest fire monitoring heat loss examination volcano activity detection examining evapotranspiration from vegetation |
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how could thermal remote sensing be used in urban settings
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detecting heat loss from buildings
examining urban heat islands |
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name 3 types of remote sensing based on wavelength regions
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visible and reflective infrared remote sensing
thermal infrared remote sensing microwave remote sensing |
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what does RADAR stand for
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radio detection and ranging
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describe differences between passive and active remote sensing
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passive uses sensors that detect the reflected or emitted EM energy from Earth's surface
active sensors detect reflected signals from objects that send out artificial energy-radar |
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name 4 components of radar (RATE)
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transmitter
receiver antenna electronic systems to analyze data |
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what are four image characteristics of radar
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radar shadow
foreshortening layover diffuse and specular reflectance |
