Principles of Remote Sensing Image from NASA Goddard

Principles of Remote Sensing Image from NASA – Goddard Space Flight Center, NOAA GOES-8 satellite, 2 Sep ’ 94, 1800 UT CS 128/ES 228 - Lecture 10 a 1

Scanning planet Earth from space CS 128/ES 228 - Lecture 10 a 2

A hierarchy of remote sensing n Satellite sensing n Aerial photography n Ground-truthing Image from Avery. Interpretation of Aerial Photographs. CS 128/ES 228 - Lecture 10 a 3

History of remote sensing n Earliest vehicle was …? n Tournachon (‘Nadar’) took 1 st aerial photograph in 1858 (since lost) n Earliest conserved aerial photograph: Boston, J. Black, 1860 n Early applications were in military reconnaissance CS 128/ES 228 - Lecture 10 a 4

WWII – heavy use of aerial reconnaissance Images: Avery. 1977. Interpretation of Aerial Photographs. 3 rd ed. Burgess Press, Minneapolis, MN. CS 128/ES 228 - Lecture 10 a 5

“Spy planes” & the Cold War CS 128/ES 228 - Lecture 10 a 6

Satellite sensing n Russian Sputnik (1957) - radio transmitter only n Rapid response by US: CORONA (1960) n Early applications: military reconnaissance CS 128/ES 228 - Lecture 10 a 7

Advantages of satellites n Wide coverage n Vertical (orthogonal) view at near-infinite height n Automated, 24/7 operation n Rapid data collection CS 128/ES 228 - Lecture 10 a 8

Spectral bands Three important spectral bands: n visible light n infrared radiation n microwave radiation Image from NASA 1987. SAR: Synthetic Aperture Radar. Earth Observing System, Vol. IIf. CS 128/ES 228 - Lecture 10 a 9

Classes of sensors Photographic n panchromatic n color Multi-spectral scanners § image scanned across sensors § sensors for many wavelengths Infrared (IR) § film (near IR) § thermal IR sensors for longer wavelengths Radar § RAdio Detection And Ranging § active imaging CS 128/ES 228 - Lecture 10 a 10

§ IR penetrates haze and light cloud Infrared cover sensors n can be used at night n used by military for camouflage detection n IR ‘signature’ often distinct from visible image CS 128/ES 228 - Lecture 10 a 11

Color IR film § Used with yellow (blueabsorbing) filter n 3 primary pigments, but not “true” (visible) color - green vegetation = red clear water = dark blue turbid water = bright blue soil = green urban areas = pale blue Top image: Committee on Earth Observation Satellites http: //ceos. cnes. fr: 8100/cdrom-98/ceos 1/irsd/content. htm Bottom image: Avery. 1977. Interpretation of Aerial Photographs. 3 rd ed. Burgess Press, Minneapolis, MN. CS 128/ES 228 - Lecture 10 a 12

Multispectral sensors n Visible + IR spectra n Comparison of film and electronic sensor spectral bands Top: Avery 1977. Interpretation of Aerial Photography. Burgess Publ. , Ninneapolis Bottom: ASTER Science page (http: //www. science. aster. ersdac. or. jp/users/parte 1/02 -5. htm#3) CS 128/ES 228 - Lecture 10 a 13

Landsat Images n Landsat 1 -4 launched 1972 – ’ 82; expired n Landsat 5 & 7 launched 1985 & 1999; both operational n TM: thematic mapper. - 7 spectral bands - designed primarily for ES themes http: //landsat. gsfc. nasa. gov/project/L 7 images. html CS 128/ES 228 - Lecture 10 a 14

TM Applications Band Spectral range (µm) “Color” Application 1 0. 45 – 0. 52 Blue-green Soil/vegetation separation 2 0. 52 – 0. 60 Green Reflection from vegetation 3 0. 63 – 0. 69 Red Chlorophyll absorption 4 0. 76 – 0. 90 Near IR Delineation of water bodies 5 1. 55 – 1. 75 Mid IR Vegetative moisture 6 10. 4 – 12. 5 Far IR Hydrothermal mapping 7 2. 08 – 2. 35 Mid IR Plant heat stress CS 128/ES 228 - Lecture 10 a 15

Hydrology example Images from Avery. Interpretation of Aerial Photographs. CS 128/ES 228 - Lecture 10 a 16

Radar sensors n active sensing n day & night, all weather n less affected by scattering (aerosols) Lo & Yeung, fig. 8. 13 n vertical or oblique perspective CS 128/ES 228 - Lecture 10 a 17

Uses of radar: altimetry n satellite-nadir distance n geoid & topographic measurements n sea elevation, tides & currents n wave/storm measurements Both images from NASA 1987. Altimetric System. Earth Observing System, Vol. IIh. CS 128/ES 228 - Lecture 10 a 18

Uses of radar: SAR n glaciology n hydrology n vegetation science n geology Image from NASA 1987. SAR: Synthetic Aperture Radar. Earth Observing System, Vol. IIf. CS 128/ES 228 - Lecture 10 a 19

Sensor resolution n Spatial: size of smallest objects visible on ground. Ranges from < 1 m to > 1 km. Inversely related to area covered by image n Spectral: wavelengths recorded. Ex. panchromatic film (~0. 2 – 0. 7 µm); Landsat Thematic Mapper bands (0. 06 to 0. 24 µm wide) n Radiometric: # bits/pixel. Ex. Landsat TM (8 bit); AVRIS (12 bit) n Temporal: for satellite, time to repeat coverage. Ex. Landsats 5 & 7 (16 days) CS 128/ES 228 - Lecture 10 a 20

Spatial resolution of satellite images A sampler of recent (civilian) satellites: Sponsor Satellite (instrument) Year Res. (m) NASA Landsat (Thematic Mapper) 1980 -90 s 30 (MSS) NASA & others EOS Terra (ASTER) 2000 15 - 90 (MSS) France SPOT-3 to 5 19932002 10 to 5 (pan) Space Imaging IKONOS-2 1999 1 (pan) 4 (MSS) Earth. Watch Quickbird-2 2001 0. 6 (pan) 2. 5 (MSS) CS 128/ES 228 - Lecture 10 a 21

Satellite image resolution Quickbird 2 n Commercial venture n 0. 63 m resolution n U. S. trying to discourage open access to finer resolution images Digitalglobe. com CS 128/ES 228 - Lecture 10 a 22

Satellite orbits Geostationary n 36, 000 km above equator Polar n varying heights n often in Sunsynchronous orbits Both diagrams from European Organisation for the Exploitation of Meteorological Satellites www. eumetsat. de/en/mtp/space/polar. html CS 128/ES 228 - Lecture 10 a 23

Satellite coverage Geostationary n no polar coverage n coverage is 24/7 n low ground resolution (~ 1 km) Polar n global coverage n coverage is discontinuous Both diagrams from European Organisation for the Exploitation of Meteorological Satellites www. eumetsat. de/en/mtp/space/polar. html CS 128/ES 228 - Lecture 10 a 24

Geostationary orbits Ex. GOES satellites n Meteorological satellites n GOES-8 at 75 o. W, GOES-9 at 135 o. W n 5 bands (1 visible, 4 thermal infrared) Image from NASA – Goddard Space Flight Center, NOAA GOES satellite, Hurricane Floyd, 15 Sep ‘ 99 CS 128/ES 228 - Lecture 10 a 25

Polar orbits Ex. Landsat & Terra satellites n 705 km height, ~100 minute orbit n 185 km swath n 16 day repeat n Sun-synchronous orbits (~0945 a. m. equator crossing) Orbit tracking data from NASA – http: //liftoff. msfc. nasa. gov/realtime/JTrack/eos. html, 5 Mar ‘ 03 CS 128/ES 228 - Lecture 10 a 26

Terra (and EOS) n Terra launched 1999 n Carries 5 instruments; the MSS imager is called ASTER (from Japan) n 14 spectral bands: - 3 VIS/near IR (15 m) - 6 short IR (30 m) - 5 thermal IR (90 m) Images from www. nasa. gov CS 128/ES 228 - Lecture 10 a 27

NYC drought The ASTER image pair depicts a 215 -square-kilometer (80 square-mile) area around Ashokan Reservoir in the Catskill Mountains, one of several Catskills reservoirs that supply water to the New York City metropolitan area. The images, taken September 18, 2000, and February 3, 2002, show a dramatic decrease in reservoir water level to the current 52 percent of capacity. Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U. S. /Japan ASTER Science Team CS 128/ES 228 - Lecture 10 a 28

Urban development study Ulaanbaatar, Mongolia - http: //corp. mmp. kosnet. com/CORP_CD_2004/ archiv/papers/CORP 2004_RADNAABAZAR_KUFF ER_HOFSTEE. PDF CS 128/ES 228 - Lecture 10 a Study used: SPOT images LANDSAT images ASTER images 1: 5, 000 maps 1: 10, 000 aerial photos 29

Ground truthing … … the fun part CS 128/ES 228 - Lecture 10 a 30