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Principles of Remote Sensing. Image from NASA – Goddard Space Flight Center, NOAA GOES-8 satellite, 2 Sep ’94, 1800 UT. Scanning planet Earth from space. History of remote sensing. Earliest vehicle was …? Tournachon (‘Nadar’) took 1 st aerial photograph in 1858 (since lost) - PowerPoint PPT Presentation
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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 9a
Scanning planet Earth from space
CS 128/ES 228 - Lecture 9a
History of remote sensingEarliest vehicle was ? Tournachon (Nadar) took 1st aerial photograph in 1858 (since lost) Earliest conserved aerial photograph: Boston, J. Black, 1860 Early applications were in military reconnaissance
CS 128/ES 228 - Lecture 9a
WWII heavy use of aerial reconnaissanceImages: Avery. 1977. Interpretation of Aerial Photographs. 3rd ed. Burgess Press, Minneapolis, MN.
CS 128/ES 228 - Lecture 9a
Spy planes & the Cold War
CS 128/ES 228 - Lecture 9a
Satellite sensingRussian Sputnik (1957) - radio transmitter only Rapid response by US: CORONA (1960) Early applications: military reconnaissance
CS 128/ES 228 - Lecture 9a
Advantages of satellitesWide coverage Vertical (orthogonal) view Multi-spectral data bands Rapid data collection
CS 128/ES 228 - Lecture 9a
Sources of EM radiationKey distinction:passive sensingactive sensing Spectral signaturesTop: Lo & Yeung, fig. 8.1 Bottom: ASTER Spectral Library (http://speclib.jpl.nasa.gov)
CS 128/ES 228 - Lecture 9a
Types of EM radiation usedThree important spectral bands:visible light infrared radiationmicrowave radiationImage from NASA 1987. SAR: Synthetic Aperture Radar. Earth Observing System, Vol. IIf.
CS 128/ES 228 - Lecture 9a
Atmospheric attenuationScatteringcaused by aerosols (water vapor, dust, smoke) more intense at shorter wavelengths why the sky is blue
Absorptioncaused by gas molecules (H2O, CO2, O2, O3) each molecule absorbs at a specific wave-length result: atmospheric transmission windows
CS 128/ES 228 - Lecture 9a
Transmission windows UV-visible-IR MicrowaveImage from NASA 1987. From Pattern to Process: The Strategy of the Earth Observing System. Vol. II.
CS 128/ES 228 - Lecture 9a
Classes of sensorsPhotographicpanchromatic color
Infrared (IR)film (near IR)thermal IR sensors for longer wave-lengthsMulti-spectral scanners sensors for many wavelengths image scanned across sensorsRadarRAdio Detection And Ranging active imaging
CS 128/ES 228 - Lecture 9a
Visual sensors: film typespanchromatic near-infrared color
Both images from Committee on Earth Observation Satellites http://ceos.cnes.fr:8100/cdrom-98/ceos1/irsd/content.htm
CS 128/ES 228 - Lecture 9a
Infrared sensorsIR penetrates haze and light cloud cover can be used at night used by military for camouflage detection IR signature often distinct from visible image
CS 128/ES 228 - Lecture 9a
Color IR filmUsed with yellow (blue-absorbing) filter 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/ceos1/irsd/content.htmBottom image: Avery. 1977. Interpretation of Aerial Photographs. 3rd ed. Burgess Press, Minneapolis, MN.
CS 128/ES 228 - Lecture 9a
Multispectral sensorsVisible + IR spectra Comparison of film and electronic sensor spectral bandsTop: Avery 1977. Interpretation of Aerial Photography. Burgess Publ., NinneapolisBottom: ASTER Science page (http://www.science.aster.ersdac.or.jp/users/parte1/02-5.htm#3)
CS 128/ES 228 - Lecture 9a
Radar sensorsactive sensing day & night, all weather less affected by scattering (aerosols) vertical or oblique perspectiveLo & Yeung, fig. 8.13
CS 128/ES 228 - Lecture 9a
Uses of radar: altimetry satellite-nadir distance geoid & topographic measurements sea elevation, tides & currents wave/storm measurements
Both images from NASA 1987. Altimetric System. Earth Observing System, Vol. IIh.
CS 128/ES 228 - Lecture 9a
Uses of radar: SAR glaciology hydrology vegetation science geology
Image from NASA 1987. SAR: Synthetic Aperture Radar. Earth Observing System, Vol. IIf.
CS 128/ES 228 - Lecture 9a
Sensor resolutionSpatial: size of smallest objects visible on ground. Ranges from < 1m to > 1 km. Inversely related to area covered by image Spectral: wavelengths recorded. Ex. panchromatic film (~0.2 0.7 m); Landsat Thematic Mapper bands (0.06 to 0.24 m wide) Radiometric: # bits/pixel. Ex. Landsat TM (8 bit); AVRIS (12 bit) Temporal: for satellite, time to repeat coverage. Ex. Landsats 5 & 7 (16 days)
CS 128/ES 228 - Lecture 9a
Spatial resolution: analog (film) imagesDepends on:lens quality & camera stability size of negative film grain
High quality aerial photograph:up to 60 lines/mm 9 x 9 (23 x 23 cm) negative scanned at 3000 dpi = ~725 megapixels if 8 bit image depth, >5 GB image size
CS 128/ES 228 - Lecture 9a
Ground resolutionG. R. = scale factor / film resolution
CS 128/ES 228 - Lecture 9a
Spatial resolution: digital (satellite) imagesA sampler of recent (civilian) satellites:
CS 128/ES 228 - Lecture 9a
Satellite image resolutionQuickbird 2Commercial venture 0.63 m resolution U.S. trying to discourage open access to finer resolution images Digitalglobe.com
CS 128/ES 228 - Lecture 9a
Satellite orbitsGeostationary36,000 km above equator Polarvarying heights often in Sun-synchronous orbits
Both diagrams from European Organisation for the Exploitation of Meteorological Satelliteswww.eumetsat.de/en/mtp/space/polar.html
CS 128/ES 228 - Lecture 9a
Satellite coverageGeostationaryno polar coveragecoverage is 24/7low ground reso-lution (~ 1 km) Polarglobal coveragecoverage is dis-continuous
Both diagrams from European Organisation for the Exploitation of Meteorological Satelliteswww.eumetsat.de/en/mtp/space/polar.html
CS 128/ES 228 - Lecture 9a
Geostationary orbitsEx. GOES satellitesMeteorological satellites GOES-8 at 75oW, GOES-9 at 135oW 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 9a
Polar orbitsEx. Landsat & Terra satellites705 km height, ~100 minute orbit 185 km swath
16 day repeat 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 9a