1. ©2008 Austin Troy Lecture 21: Major Types of Satellite Imagery By Austin Troy and Weiqi Zhou University of Vermont ------Using GIS-- Introduction to GIS

2. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Major Satellite Systems High spatial resolution – Quickbird, IKONOS, OrbView-3, SPOT-5 PAN, IRS- P6 Medium spatial resolution – Landsat-5 TM, Landsat-7 ETM+, ASTER, SPOT Low spatial resolution – MODIS, ENVISAT, GOES, AVHRR, MSS

3. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Orbits Most of these satellites are in sun-synchronous orbit The satellite passes over the same part of the Earth at roughly the same local time each day Its “inclination” is about 8 degrees off of polar orbit The fact that the earth is not perfect sphere makes the orbital plane rotate slowly around the earth (this would not happen if it were perfectly polar)

4. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Orbits Source:http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbo ok_htmls/chapter6/chapter6.html

5. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Orbits The slow motion of that orbital plane matches the latitudinal motion of the sun in the sky over the year Maintains similar sun angles along its ground trace for all orbits That means that the area the sun flies over always get the same sunlight angle, which gives constant lighting Source:http://hdsn.eoc.nasda.go.jp/experience/rm_kiso/sat ellit_type_orbit_e.html

6. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Scanners Pushbroom (along track) vs. Whiskbroom (across track) SPOT and IKONOS: Pushbroom Landsat: Whiskbroom Pushbroom scanners generally have higher radiometric resolution because they have longer “dwell time” than across-track scanners, which move laterally across landscape as also move forward Source: http://www.sci-ctr.edu.sg/ssc/publication/remotesense/spot.htm

7. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT First started by NASA in 1972 but later turned over to NOAA Since 1984 satellite operation and data handling are managed by a commercial company EOSAT LANDSAT-7 launched in 1999; developed scan line error in 2003 Only 5 is still working; outdated Source: http://www.sci-ctr.edu.sg/ssc/publication/remotesense/landsat.htm

8. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT LANDSAT 4 and 5 had two types of sensors, MSS (multi-spectral scanner) and TM (thematic mapper): MSS:Started on LANDSAT 1, terminated in late 1992. 80 m resolution with four spectral bands from the visible green to the near-infrared (IR) wavelengths. Only Landsat 3’s MSS sensor had a fifth band in the thermal-IR. Introduction to GIS

9. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Thematic Mapper * * * Mid infra red Spatial and spectral resolution Radiometric resolution: 8 bits (256 DNs) Temporal resolution: 16 days.

10. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT TM An example:August 14, 1999 (left) and October 17, 1999 (right) images of the Salt Lake City area Differences in color due to growing season

11. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT 7 Uses a new sensor called Enhanced Thematic Mapper Plus (ETM+) Stressed continuity with LANDSAT 4 and 5 in that uses similar orbit and repeat patterns, as well as a similar 185 km swath width for imaging Check out the movie Source: http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_htmls/chapter2/chapter2.html

12. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 Characteristics of ETM+: Band wavelength spectrums are slightly different from LANDSAT 5 TM Enhanced Thematic Mapper Plus

13. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT TM: applications Introduction to GIS BandNominal Spectral location applications 1BlueWater body penetration, soil-water discrimination, forest type mapping, cultural feature ID 2GreenGreen reflectance peak of veg, for veg ID and assessment of vigor, cultural feature ID 3RedChlorophyll absorption region, plant species differentiation, cultural feature ID 4Near infra redVeg types, vigor and biomass content, dilineating water bodies, soil moisture assessment 5mid infra red (1.55- 1.75  m) Veg moisture, soil moisture, diff of soil from clouds 6Thermal infra redVeg stress analysis, soil moisture, thermal mapping 7mid infra red(2.08- 2.35  m) Discriminating mineral and rock types, veg moisture

14. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Its repeat cycle is about 16 days and always crosses equator at around 10 AM. Orbit takes about 99 minutes (14.5 per day) Distance between ground tracks of consecutive orbits is 2752 km at equator because of the earth’s rotation By following earth’s rotation with each pass, it can keep crossing the equator at the same time Introduction to GIS

15. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Swath is 183 km wide, although that includes overlap, since data frame is 170 km 233 orbits, for each 16-day cycle Source: http://eosims.cr.usgs.gov:5725/DATASET_DOCS/landsat7_dataset.html

16. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Scenes are then indexed by the path and a row Source: http://eosims.cr.usgs.gov:5725/DATASET_DOCS/landsat7_dataset.html

17. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT 7 LANDSAT 7 has an excellent mission coverage archive Source: http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_htmls/chapter6/chapter6.html

18. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Products All data older than 2 years return to "public domain" and are distributed by the Earth Resource Observation System (EROS) Data Center of the US Geological Survey Available at http://edcwww.cr.usgs.gov/products/satellite/landsat7.html http://edcwww.cr.usgs.gov/products/satellite/landsat7.html The LANDSAT Reference system catalogues the world into 57,784 scenes, each 115 miles (183 kilometers) wide by 106 miles (170 kilometers) long.

19. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Composite of Red, Green and Blue. Shows manmade features as well as densely forested areas and agricultural lands.

20. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Composite of NIR, Red and Green. Shows manmade features as well as densely forested areas and agricultural lands.

21. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Composite of shortwave infrared, Near-Infrared and Red. Shows manmade features as well as densely forested areas and agricultural lands

22. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Introduction to GIS

23. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Introduction to GIS Composite of shortwave infrared, Near-Infrared and Red. Shows manmade features as well as densely forested areas and agricultural lands

24. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Introduction to GIS Same bands: shows wetlands, urban, open water, forest

25. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 LANDSAT Imagery Introduction to GIS Same bands: light yellow-green color represents northern hardwood forest. The dark green patches represent various conifer species

26. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT Launched by France Stands for Satellite Pour l'Observation de la Terre Operated by the French Space Agency, Centre National d'Etudes Spatiales (CNES).

27. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT SPOT 1 launched 1986, decommissioned and the reactivated in 1997 SPOT 2 launched 1990, still going SPOT 3 launched 1993 and stopped functioning 1996 SPOT 4 launched in 1998, still going SPOT 5 launched in 2002

28. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT Each SPOT satellite carries two HRV (high-resolution visible) sensors, constructed with multilinear array detectors, or “pushbroom scanners” These record multispectral image data along a wide swath Source: http://www.sci-ctr.edu.sg/ssc/publication/remotesense/spot.htm

29. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT The position of each HRV unit can be changed by ground control to observe a region of interest that is at an oblique angle to the satellite—up to ±27º relative to the vertical. Off-nadir viewing allows for acquisition of stereoscopic imagery (because of the parallax created) and provides a shorter revisit interval of 1 to 3 days. Source: http://www.sci-ctr.edu.sg/ssc/publication/remotesense/spot.htm

30. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT Oblique viewing capacity – Greatly improve the viewing frequency (temporal resolution): allows it to image any area within a 900 kilometer swath; can be used to increase the viewing frequency for a given point during a given cycle. For a given location, the interval ranges from a maximum of 4 days to a minimum of 1 day. – Any point on 95% of the earth may be imaged any day by one of the three satellites. Source:http://www.spot.com/home/system/introsat/acquisi/welcome.htm

31. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT Source: http://www.spotimage.fr/html/_167_224_555_233_.php Two modes: panchromatic and multispectral

32. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT Some examples: mosaic false color tiles of Australia

33. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 SPOT

34. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS Developed by Space Imaging, launched 1999 Has sun-synchronous orbit and crosses equator at 10:30 AM Highly maneuverable: can point at a new target and stabilize itself in seconds, enabling it to follow meandering features The entire spacecraft moves, not just the sensors

35. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS Can collect data at angles of up to 45°from the along track and across track axes: allows for side by side and fore and aft stereoscopic imaging At its nadir it has 11 km swath width 11 km by 11 km image size, but user specified strips and mosaics can be ordered Employs a linear array scanner

36. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS Resolutions – Panchromatic band (.45 to.90  m) at 1 m spatial resolution. – Four multispectral bands at 4 m spatial resolution. Blue (.45 to.52  m) green (.51 to.60  m), red (.63 to.70  m), near IR (.76 to.85  m) – Radiometric resolution: 11 bits, or 2048 values. – Temporal: Ground track repeats every 11 days. –For a gallery of images, see: http://www.satimagingcorp.com/gallery-ikonos.html http://www.satimagingcorp.com/gallery-ikonos.html

37. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS data Here is 1m IKONOS view of suburbs, near winter Olympics Source: spaceimaging.com

38. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS data 1m IKONOS view of Dubai Source: spaceimaging.com

39. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS data 1m IKONOS pan image of Rome Source: spaceimaging.com

40. ©2008 Austin Troy Materials by Austin Troy and Weiqi Zhou except where noted © 2007 IKONOS data 1m image of “Survivor” camp in Africa Source: spaceimaging.com

41. ©2008 Austin Troy Some other satellite platforms Quickbird IRS system: from India ERS: European remote sensing satellite Aster: a USGS sensor flying on Terra Satellite AVHRR: radar