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76 Cards in this Set
- Front
- Back
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Greenhouse Effect
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atmosphere lets in the suns emitted wavelength but does not let out the earth's reemitted dominant wavelength
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Lambertian vs Specular Reflection
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Lambertian = perfectly scattered
Specular = perfectly reflected in one direction |
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Absorption
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photons hit surface and change atoms and molecules thus absorbing energy; the process by which radiant energy is converted to other forms of energy
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Black Body
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One that emits radiation at the maximum possible rate at all wavelengths
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Wien's Displacment Law
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the dominant wavelength of emitted energy from a body is determined by
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Earth's absorptions and emissions
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absorbs solar energy at high Frequencies (visible) and radiates energy by Emission at low frequencies (Infrared)
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Pixel
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a brightness value associated with a given area on the ground. For color, a pixel has three brightness values, onr for Red, Green , and Blue
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Radiance
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radiant flux density scattered from a surface per unit solid angle
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Reflectance
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the radiance leaving a surface divided by the irradiance endtering a surface
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Why is the sky blue?
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Because of Raleigh Scattering - gas molecules are much smaller than wavelength of light. Shorter waves are scattered more, because they are closer in size to the molecules and because they contain higher energies
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Why do shorter wavelengths have greater energy?
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Q (energy) = hf
f = c/wavelength Q=hc/wavelngth wavelength goes down energy goes up |
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Why are sunsets orange?
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Mie scattering - dust particles are similar in size to the wavelengths of light. Shorter waves are more fully blocked than the longer waves, producing orange and red skies
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Why are clouds white?
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Non-selective scattering - particle sizes (water molecules) are much larger than the wavelengths of light, so all wavelengths are scattered equally, giving a white color to clouds and fog
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Camera obscura
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first permant image - 1826 - pewter plate coated with Bitumen, exposed, then washed with oil
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Polar Orbit
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90 degrees to the equator
entire surface of the earth can be covered twice a day with AVHRR |
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Sun-synchronous orbit
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Ex: aster
special case polar orbit: does not go directly over the poles, but at a greater angle |
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geo-synchronous orbit
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always located directly above the equator with a zero incilnation
very high orbit |
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Landsat MSS
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Spectral Region: .5 to 1.1 um (visible and reflected IR)
Spectral Bands: 4 Swath Width: 185x185km Pixel Size: 79 by 79 m in visible and reflected IR |
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Landsat 4/5 TM
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Spectral Region:
VIS and RIR - .45 to 2.35 um (bands 1-5 and 7) TIR - 10.5 - 12.5 um (band 6) Bands: 7 Swath Width: 185x170km Pixel Size: VIS and RIR - 30 by 30 m Thermal IR - 120 by 120 m 8 bit sensor 705 km flyover inclination: 98.2 degrees |
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f/stop
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focal length / lens diamter
narrower diameters give greater depth perception |
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Methods for measuring elevation
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1) Comparing shadow lengths
2) Relief Displacement 3)Differential Parallaz |
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Differential Parallaz
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can be found by finding the differneces in the distances between the top and bottom of the object on adjacent photos, moving them close together along the line of flight direction
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Orthophotos
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require six pieces of data for each data point: x,y,z roll,pitch, and yaw
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Supervised Classification
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giving the computer information about what end members I am interested in
Ex: Minimum Distance Parallelpiped Mahalanobis Distance Maximum Likelihood |
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Unsupervised Classification
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letting the program sort out differences on its own
Ex: K-means and ISODATA |
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Minimum Distance
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takes one band on the y axis and another on the x axis and plots set classifications. The distance from the mean of each class on the plot is calculated for any point. The class that is closest to the point is the class of the point
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Parallelpiped
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classes plotted on x/y axis with one band as x and another as y. boxes drawn around classes. whichever box a pixel falls in on the plot is the class it is assigned too
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Maximum Likelihood
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defined classes plotted on x/y axis, Z axis is the probability density that a point on the x/y axis belongs in each class
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Mahalanobis Distances
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points are assigned to class based on how high a density of each class they are in
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K-means
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Analyst provides the number of clusters ENVI assigns each pixel to the cluster whose Mean vector is closest. The program then Iterates until no more change occurs
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ISODATA
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Iterative Self‐Organizing DATA analysis
Like K‐Means, except that the number of clusters Can change from one iteration to the next. If a cluster Has too much variability it is split. Clusters that fall Below a certain number of pixels are eliminated. |
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Phenology
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changes in plant growth cycles
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Photosynthesis needs
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A leaf needs water, CO2, and sunlight, and growth can occur in the presence of Chlorophyll
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Palisade parenchyma and spongy parenchyma cells
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VNIR light is transmitted through the cuticle and upper epidermis to ... ; also where photosynthesis occurs ; form in Mesophyll nearest to where light enters the plant
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Dark-adapted plants have...cuticles
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thin cuticles to allow more light to enter
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Plants growing in bringht light have... cuticles
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thick cuticles to guard against excessive water loss
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chlorophyll b and a absorb in...
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the blue (.43 and .45 um) and the red (.66 and .65 um)
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Carotenes absorb in...
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in violet, blue, and a little green,
appears yellow |
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What happens when plants senescence or undergo stress...
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Chlorphyll disappears and the carotenes and other pigments can dominate turning leaves yellow or red/ fall colors
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What wavelengths do healthy plants reflect the most?
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NIR - 700-1200 nm range
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Why do plants reflect NIR?
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To avoid overheating otherwise proteins would denature
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Additive reflectance
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addition energy reflected by lower leaves
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Dominate factors controlling leaf reflectance
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leaf pigments in the palisade mesophyll: chlorohpyll a,b / b-carotene etc
scattering in the spongy mesophyll leaf water content |
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Effect of Water in Plant Reflection
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turgid plants absorb 1.3-2.5 um as the leaves dry, absorption decreases and reflectance increases--because energy is scattered at intercellular walls
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BDRF
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Bidirectional Reflectance Distribution function - ratio of radiance reflected in one direction to the sun's incident irradiation from another direction
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Plant reflectance will vary according to..
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different planting times during season
differences in irrigation differences in fertilization or weeding different row spacing between crops different canopy structure |
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NDVI
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Normalized Difference Vegetation Index:
NDVI = (NIR - R)/(NIR + R) = (TM4-TM3)/(TM4 + TM3) |
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NDWI
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Normalized Difference Water Index:
NDWI = (NIR-SWIR)/(NIR+SWIR) |
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When do you want to acquire data for classifying vegetation:
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acquire data early in the growing season because different plants grow at different rates creating different spectral signatures
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When do you want to acquire data for monitoring biomass:
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If the goal is monitoring biomass, collect at the height of the growing season
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Hourglass approach to spectral ID
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Decreasing Noise: Minimum Noise Fraction
Finding end-members: Pixel Purity Index Visualizing end-members: nD-visulizer ID: SAM, SFF Mapping: SAM, Mixture Tuned Matched Filter |
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Mimimum Noise Fraction
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determines the dimensionality of the data
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Pixel Purity Index
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finds the most spectrally pure or "extreme" pixels in multispectral and hyperspectral data
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n-Dimensional Visualizer
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view, understand, and cluster pixels to find the corners of the data cloud in n-space and thus get scene endmembers
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Spectral Angle Mapper
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measures the angle between spectra and a reference spectrum by treating them as vectors in n-dimensional space
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Mixture Tuned Matched Filter
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computes both the matched filter score and the measure of infeasibillity that the match is correct. We choose the area of high score and low infeasibility
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Silicate Mineral Melting Temperatures
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High --> Low
OlivinePyroxenAmph.MicaClayQuartz |
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Silicate
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Solitary SiO4 - Olivine
Chains of SiO4 - Pyroxenes Double chains - Amphiboles Sheets - micas 3D framework - quartz and feldspars Ring structures: Beryl, Zeolites |
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Color Centers - Electronic Process
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imperfections and lattice defects in crystals can produce discrete energy levels and electrons can bind to them. Movement of an electron into such an energy level can cause color changes, as seen in minerals like fluorite
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Conclusions on TIR imaging
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can be a powerful way to map not only "hot things" like lava and fire, but also to map lithology
does best in arid regions whith little moisture or vegeation |
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Sediment detection
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Visible range (580-690 nm) can provide information on the type of suspended
NIR (714-880 nm) may give info on the amount of SM. |
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Why are sea surface temps cool in the east but high in the west?
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Because of upwelling
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El Nino
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SST's are higher than normal in eastern pacific. surface waters become nutrient poor and there is significant die off of organisms
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La Nina
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cooler in the east pacific
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How does one distinguish snow from clouds in AVHRR or GOES imagery?
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clouds and snow have same reflection in VNIR but in SWIR clouds reflect a lot
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Porosity
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ability to hold water
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Permeability
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ability to pass water
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Solid phase minerals in soils
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primary minerals: quartz, feldspar, micas
secondary: clays (kaolinite, illit, montmorillonite), carbonates, sulfates, phosphates, oxides |
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Liquid gas phase in soils
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water CO2 O2 and other organic matter
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Clay minerals in soils
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Muscovite-->illite
biotite-->vermiculite illite forms with moderate acidity and alters to smectite in high acidity kaolinite forms in very waeathered, leached soils illite and vermiculite are associated with youthful soils smectite is middle stage soil kaolinite is old soil illite and smectite in colder climates kaolinite in warm temperate regions hematitie forms in tropical soils |
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Silt and sand reflectance
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silt reflects much better than sand, sand reflects better than organic matter
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Land Degradation results
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in an increase in albedo or surface reflectivity
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Mt. Rainier Study
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Hydrothermally altered rocks on strat volc are closely linked to destructive volcanic debris flows and catastrophic edific failure. altered rocks form zones of weakness along fractures, dikes and bedding surfaces. they contribute to formation of large, cohesive debris flows
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Classification and Flow of Volcanic ROcks
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Basalt Andesite Dacite Rhyolite
1160C---------------------900C Low Resistance----High Resistance Decreasing Mobility--------> |
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Geoid
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location of sea level around the earth
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Lidar
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light detection and ranging - a laser radar in light frequency range, uses photons where radar uses electromagnetic waves
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