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
color gun
colour composite
equipment used to display a color pixel on a screen through the use of the colours red, green, and blue
an image formed by placing a band of imagery into each of the three colour guns to view an image in colour rather than grayscae
true colour composite vs. false colour composite
aranged normally vs. arranged with different colours
.standard false composite: when infrared is in red gun
z value
the elevation assigned to an X/Y coordinate
vertical datum
a baseline used as a starting point in measuring elevation values( which are either abive or below this value)
Much geospatial data in N.A utilize the _____ as this origin point for elevations
NAVD88(North American Vertical Datum 1988)
Digital Raster Graphic
Digital Line Graph
a scanned version of a USGS topographic map that has been georeferenced so that they’ll match up with other geospatial data sources when used in GIS.
the features such as roads, rivers, or boundaries digitized
-vector datasets representing transporation features,hydrography features, or boundaries
Digital Terrain Model
a representation of a terrain surface calculated by measuring elevation vaalues at a series of locations
-used in conjunction with GIS
X and Y:
X, Y, and Z:
X, Y, and Zs:
2 dimensional -no z value 2.5 dimensional -one z value for each coordinate 3 dimensional -multiple z values for each coordinate
TIN
Triangulated Irregular Network
- a terrain model that allows for non-equally spaced elevation points to be used in the creation of the surface
- selected elevation points deemed most important are used in constructing the model
- type of DTM
DEM
Digital Elevation Model
- a representation of the terrain surface, created by measuring a set of equally spaced elevation values
- can be converted to a raster grid representation for use with other geospatial data, such as satellite images or GIS
- DEM resolution size is equal to raster grid cells size
LIDAR
a process in which a series of laser beams fired at the ground from an aircraft is used both to create highly accurate elevation models and also to measure the height of objects from the ground
point cloud
name given to the massive number of elevation data measurements collected by lidar
Digital Surface models
a measurement of the heights of ground elevations as well as the objects on top of the ground as captured by LIDAR
the industry standard data format used for LIDAR data is ___
LAS
slope aspect
the direction that a slope is facing
hillshade
a shaded relief map of the terrain created by modelling the position of the sun in the sky relativve to the landscape
sun altitude
sun azimuth
the value between 0 and 90 used in constructing a hillshade to model the suns elevation above the terrain
the value between 0 and 360 used in constructing a hillshade to model the suns position in the sky to show the direction of the suns rays striking the surface
draping
base heights
a process in which an image is given z values to match the heights in a digital terrain model
the z values of a digital terrain model that can then be applied to an image in the process of draping
vertical exageration
a process whereby the z-values are artificially enhanced for purposed of terrain visualization
____ are working maps
charts
geographic scale vs. map scale
geographic is real-world size
large scale map means…
smaller area shown
1:1 vs 1:40,000
largest scale is 1:1
small scale maps mean…
larger area shown
1:1 vs 1:40,000
smallest scale is 1:40,000
GPS
A technology usinng signals broadcast from satellites for navigation and position determination on earth
constellation
the full complement of sattelites comprising a GNSS
almanac
ephermis
pseudorange
trilateration
multipath
data concerning the status of GPS sattelite, which is included in the information being transmitted by the sattelite
data refering to the GPS sattelites position in orbit
the calculated distance between a GPS sattelite and reciever
finding a location in relation to three points of reference
an error caused by delay in the signal due to reflecting from surfaces before reaching the reciever
Differential GPS
a method of using a ground based correction in addition to the sattelite signals to determine position
-need to have known coordinates
Wide area augemented system
a sattelite based augmentation system that covers the united states and other portions of N.A
-imporves overall GPS position accuracy
swath width
the width of the ground area the sattelite is imaging as it passes over earth surface
spatial resolution
the ground area represented by one pixel of sattelite imagery
Pan-sharpening
the technique of fusing a higher resolution panchromatic band with lower resolution multispectral bands to improve the clarity and detail seen in the image
temporal resolution
spectral resolution
length of time a sensor takes to come back and image the same location on the ground
-finer a sensor’s temporal resolution, the fewer days it will take between return times
the bands and wavelengths measured by a sensor
Describe how Landsat 1,4,5,7,and 8 are equipped
1- MSS(multispectral scanner) which can map 4 bands
4,5- added TM(Thematic Mapper) which can map seven bands
7-had neither MSS or TM but had ETM+(Enhanced Thematic Mapper Plus)
-seven bands+ an 8th band which is panchromatic
8-OLI(Operational Land Imager), which has similar capabilities to ETM+
- TIRS:Thermal infrared sensor, the instrument that aquires thermal imagery
- 2 new bands aimed at monitoring clouds and coastal zones
- so 3 new bands making 11
