Midterm Flashcards
remote sensing
is the process of collecting data about objects or landscapes without coming in direct physical contact with them
airborne
attached to an airplane or drone
spaceborne
satellite or outer space
standard unit (SI)
metric system
algorithm
a set of instructions for solving a problem
vector data
data represented with points, lines and polygons, GIS data
raster data
Data within pixel on an image
blue-green-red
blue: .4 - .5 microns
green: .5 - .6 microns
red: .6 - .7 microns
kilo
thousand
mega
million
giga
billion
terra
trillion
infrared
0.7-3 microns
near-IR
0.7-1.3 microns
thermal
3-14 microns
microwaves
1cm - 1m, used in RADAR
panchromatic
.4-.7, whole color spectrum but gives a picture in black and white
normal color
shows the visible
color infrared
infrared band; colors we can’t see at all with our eyes
vertical angle
looking directly above, 2D
oblique angle
from an angle or from the side, gives 3D images and data
USGS
United States Geologic Survey
NASA
National Aeronautics and Space Administration
NOAA
National Oceanic and Atmospheric Administration
LASER
light amplification by stimulated emission of radiation
JPL
jet propulsion laboratory
image
made of of pixels
pixel
make up image, picture elements
DN
digital number, within pixels, contains data that can be turned into a color
spectral resolution
number of bands a sensor or satellite has or uses
band
refer to a specific wavelength range of the electromagnetic spectrum that is used to capture and measure the reflectance or radiance of an object or surface
spatial resolution
- size or resolution of an image
- 10m vs 100m
- larger number means lower resolution
temporal resolution
how often a sensor returns to a particular area; repeat time
Landsat 4-5 (TM), 7 (ETM), 8-9 (OLI, TIRS)
- spatial resolution: 15m, 30m
- temporal resolution: 16 days
- spectral resolution: 7 bands (TM), 8 bands (ETM), and 11 bands (OLI, TIRS)
MODIS (EOS satellites)
- spatial resolution: 250, 500m, 1000m
- temporal resolution: 1-2 days
- Spectral resolution: 36 bands
VIIRS
- spatial resolution: 375m, 750m
- temporal resolution: Daily, 8-Day, 16-Day, Monthly, Yearly
- spectral resolution: 22 bands
SRTM
- Shuttle radar topography mission
- One time shuttle
- 30m US, 90m global
- provided topographical data we still use today
Sentinel 2
- temporal resolution: 5 days
- spatial resolution: 10m, 20m, 60m
- spectral resolution: 13 bands
thermal remote sensing applications and what satellites and sensor?
- Use landsat, modis, VIRS
- sea surface temperatures
- climate change
- wildfires
- predict storms
spectral signatures
- dominate color of an item
- helps identifies the item when image is taken in the air
- for ex: vegetation usually green
- spectral reflection of plants, can be used to classify imagery
- can also identify water
phenology
- the study of the timing of recurring biological events, the causes of their timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different species
- basically the study of cyclical patterns (ex: when leaves drop, when plants flower, agricultural patterns, etc)
- trees losing their leaves agricultural patterns
NDVI
- Normalized Difference Vegetation Index
- quantifies vegetation by measuring the difference between near-infrared (which vegetation strongly reflects) and red light (which vegetation absorbs)
- basically measures changes in greeness
- measure of photosynthetic activity, goes from -1 to 1.
passive remote sensing
- record electromagnetic energy that is naturally reflected or emitted from the surface of the Earth
- reflective and emitted energy
- thermal sensors, Landsats
active remote sensing
- provide their own illumination that is transmitted from the sensor towards Earth; Whatever “backscattered” energy comes back is then recorded by the remote sensor.
- gives off pulses
- Radar, LiDAR
- Lasers and microwaves
RADAR
- Radio Detection and Ranging (sometimes called active microwave remote sensing)
- uses microwaves
- best for topography and micro-topography
LIDAR
- Light Detection and Ranging
- transmits relatively short wavelength
InSAR
- Interferometric Synthetic Aperture Radar
- Produces DEMS (3D maps)
- Studies earthquakes in real time
- Was on SRTM
small footprint LIDAR
- LIDAR discrete returns system, All terrain mapping
- Samples returned energy from each outgoing laser pulse
- Most commercial airborne LIDAR is this kind
- data recorded as x,y,z points
large foot print LIDAR
- LIDAR waveform systems
- records the continuous range of the energy pulse (intensity) reflected by surfaces in the vertical dimension
- Captures data like a flashlight, instead of like a laser pointer
- Waveforms systems are ICESat, GEDI
How is LIDAR processed and used?
- Uses algorithms to process and create detailed 3D maps and models
- Coastal erosion
- Canopy height
- Earthquakes
Google Earth Engine and how its done?
- Allows you to zoom in anywhere on earth; can see how something has changed
- Took all landsat and shows changes over past 40 years
NOAA GOES
- NOAA made GOES satellite
- most of it is thermal, gives info on weather.
- Real time weather
- Fire, moisture content
FIRM (Global Fire website)
- global fire weather set since 2000
- can see every fire on earth today
- uses Landsat modis
- threshold 300 d Fahrenheit
Global forest cover change, how did they do it?
- see how vegetation changes
- took NDVI and saw if greenness increased or decreased and came back
- Use a threshold for what they think forest is and over a certain timeframe to show how its changed
