Remote Sensing Data Acquisition. 1. Major Remote Sensing Systems

Remote SensingRemote Sensing

Data AcquisitionData Acquisition

1. Major Remote Sensing 1. Major Remote Sensing SystemsSystems

Major Remote Sensing SystemsMajor Remote Sensing Systems

► Aerial photographyAerial photography ► Electro-Optical remote sensingElectro-Optical remote sensing ► Microwave remote sensingMicrowave remote sensing ► Close range remote sensingClose range remote sensing

Aerial PhotographyAerial Photography

► Detector Detector ► Process Process ► VehicleVehicle► Products: aerial photographs Products: aerial photographs

► http://nationalmap.gov/viewer.html

► http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm

Electro-Optical Remote SensingElectro-Optical Remote Sensing

► Detector Detector ► Process Process ► VehicleVehicle► Products: Digital images Products: Digital images

http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=4396

Buffalo, NY November 20, 2000

http://www.esri.com/news/pressroom/hurricanemaps.html

Biloxi Coast–Before Hurricane Katrina, April 12, 2005

Biloxi Coast–After Hurricane Katrina, August 31, 2005.

Microwave Remote SensingMicrowave Remote Sensing► Uses antennas as Uses antennas as

detectorsdetectors► Passive microwave Passive microwave

systems systems ► Active microwave Active microwave

systems, RADAR systems, RADAR

http://www.erh.noaa.gov/buf/

http://rst.gsfc.nasa.gov/Sect8/Sect8_3.html

Close Range Remote SensingClose Range Remote Sensing

► Visual interpretation vs. digital image Visual interpretation vs. digital image processing processing

2. Resolutions2. Resolutions

► Spectral resolution Spectral resolution ► Radiometric resolution Radiometric resolution ► Spatial resolution Spatial resolution ► Temporal resolutionTemporal resolution

Spectral ResolutionsSpectral Resolutions

AVIRIS

Landsat 7

French SPOT

DS-1260

1.0m 2.0m

AVIRIS

Landsat 7

French SPOT

DS-1260

1.0m 2.0m

AVIRIS

Landsat 7

French SPOT

DS-1260

1.0m 2.0m

Spectral ResolutionsSpectral Resolutions

Green

Red Near Infrared NIR

http://rst.gsfc.nasa.gov/Intro/Part2_17.html

► The dimension and the number of specific The dimension and the number of specific wavelength intervals in the EM spectrum to wavelength intervals in the EM spectrum to which a sensor is sensitive, e.g. B, G, R NIR which a sensor is sensitive, e.g. B, G, R NIR bandsbands

Radiometric ResolutionRadiometric Resolution

► The sensitivity of a detector to differences The sensitivity of a detector to differences in signal strength as it records the radiant in signal strength as it records the radiant flux reflected or emitted from the terrainflux reflected or emitted from the terrain

256 levels 16 levels 4 levels 2 levels

8 bit 4 bit 2 bit 1 bit

Spatial ResolutionSpatial Resolution

► A measure of the smallest angular or linear A measure of the smallest angular or linear separation between two objects that can be separation between two objects that can be resolved by the sensor, 30m, 1m, 1km resolved by the sensor, 30m, 1m, 1km

10m 20m 40m 80m

Temporal ResolutionTemporal Resolution

► How often a given sensor obtains imagery How often a given sensor obtains imagery of a particular area, e.g., 16 days, daily of a particular area, e.g., 16 days, daily

Pixels and IFOVPixels and IFOV

► Pixel - picture Pixel - picture elementelement

► IFOV - Instantaneous IFOV - Instantaneous Field of View Field of View the ground area the ground area viewed by the sensor viewed by the sensor at a given instant at a given instant

3. Color Theory3. Color Theory

► Additive primariesAdditive primaries► Subtractive primariesSubtractive primaries

Additive PrimariesAdditive Primaries

► blue, green, and red blue, green, and red  superimposing blue, green, and red light:  superimposing blue, green, and red light:

blue  + green + red = white blue  + green + red = white      green + red  = yellow      green + red  = yellow      green + blue = cyan      green + blue = cyan      red   + blue = magenta      red   + blue = magenta

Color TheoryColor Theory

► Yellow, magenta, and cyan are Yellow, magenta, and cyan are complements of blue, green, and red, complements of blue, green, and red, respectively respectively

►   Various combinations of the three primaries Various combinations of the three primaries produce different colorsproduce different colors

Subtractive PrimariesSubtractive Primaries

► yellow, magenta, and cyan yellow, magenta, and cyan each absorbs its complementary color from each absorbs its complementary color from white light white light           yellow  = white - blue           yellow  = white - blue           magenta = white - green           magenta = white - green           cyan = white - red           cyan = white - red

Subtractive PrimariesSubtractive Primaries

► Superimposing yellow, magenta, and Superimposing yellow, magenta, and cyan dye: cyan dye:       yellow  + magenta + cyan = black       yellow  + magenta + cyan = black        yellow  + magenta = red        yellow  + magenta = red        yellow  + cyan = green        yellow  + cyan = green        magenta + cyan = blue        magenta + cyan = blue

True and False Color ImagesTrue and False Color Images

True and False Color ImagesTrue and False Color Images

http://www.crisp.nus.edu.sg/~research/tutorial/opt_int.htm

► Readings Chpt 2.7Readings Chpt 2.7

4. Introduction of Satellite 4. Introduction of Satellite Systems Systems

►   Land observation satellite systemsLand observation satellite systems

                vehicles - spacecraft vehicles - spacecraft         devices - electro-optical sensors         devices - electro-optical sensors         images - digital images         images - digital images         target - earth resources        target - earth resources

Satellite SystemsSatellite Systems

►   Advantages vs. aerial photography Advantages vs. aerial photography

provide a synoptic view provide a synoptic view systematic, repetitive coverage systematic, repetitive coverage multiple spectral information multiple spectral information digital format for quantitative analysis digital format for quantitative analysis less expensive less expensive

History of Satellite SystemsHistory of Satellite Systems

► Landsat (Land Satellite) system Landsat (Land Satellite) system  - launched in 1972  - launched in 1972  - first satellite for observation of the earth's  - first satellite for observation of the earth's landland

areas areas  - important in earth resources studies and a - important in earth resources studies and a

model for later satellite systemsmodel for later satellite systems

History of Satellite SystemsHistory of Satellite Systems

► Early Landsat (1,2,3) was named Earth Resources Early Landsat (1,2,3) was named Earth Resources Technology Satellite (ERTS) and designated by a Technology Satellite (ERTS) and designated by a letter, i.e. A,B,C, renamed later as Landsat 1, 2, 3letter, i.e. A,B,C, renamed later as Landsat 1, 2, 3

► Early Landsat applied spectrums used in aerial Early Landsat applied spectrums used in aerial photography but at a satellite altitudephotography but at a satellite altitude

► Early Landsat carried Return Beam Vidicon (RBV) Early Landsat carried Return Beam Vidicon (RBV) and Multispectral Scanner (MSS) sensor systems and Multispectral Scanner (MSS) sensor systems

► New generation of Landsat (4,5,7) carries MSS and New generation of Landsat (4,5,7) carries MSS and Thematic Mapper (TM) and other more Thematic Mapper (TM) and other more sophisticated sensor systems sophisticated sensor systems

Satellite OrbitsSatellite Orbits

► Geosynchronous orbits Geosynchronous orbits ► Sun-synchronous orbitsSun-synchronous orbits► InclinationInclination► Ascending and descending nodes   Ascending and descending nodes   

Geosynchronous OrbitsGeosynchronous Orbits

► Revolve at an angular rate that matches Revolve at an angular rate that matches the earth's rotation the earth's rotation

► Weather satellites, communication Weather satellites, communication satellitessatellites

► Views the full range of variation of solar Views the full range of variation of solar illumination illumination

http://www.crisp.nus.edu.sg/~research/tutorial/spacebrn.htm

Sun-Synchroneous OrbitsSun-Synchroneous Orbits

http://www.crisp.nus.edu.sg/~research/tutorial/spacebrn.htm

► Maintain a constant angular relationship Maintain a constant angular relationship with the solar beam, the satellite will always with the solar beam, the satellite will always pass overhead at the same local time for pass overhead at the same local time for similar illumination and shadowing similar illumination and shadowing conditions conditions

http://www.youtube.com/watch?v=LttI1IofXRI

Satellite OrbitsSatellite Orbits

► Inclination Inclination the angle between the orbital plane and the angle between the orbital plane and the equatorial plane the equatorial plane

► Coverage of the earth's surface Coverage of the earth's surface

http://www.atmos.umd.edu/~owen/CHPI/IMAGES/orbitss.html

Satellite OrbitsSatellite Orbits

► Descending node Descending node  - the point the satellite  - the point the satellite crosses equator on crosses equator on southward tracksouthward track

►   Ascending node Ascending node  - the point the satellite  - the point the satellite crosses equator on crosses equator on northward tracknorthward track

http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/chapter2/chapter2_2_e.html

Satellite OrbitsSatellite Orbits

► Most satellites cross over the equator at Most satellites cross over the equator at about 9:30am, an optimal time with about 9:30am, an optimal time with respect to sun angle and cloud cover respect to sun angle and cloud cover

ReadingsReadings

► Chapter 6Chapter 6