Fundamentals of Remote Sensing. Dr. John Chadwick University of North Carolina at Charlotte

Transcription

1 Fundamentals of Remote Sensing Dr. John Chadwick University of North Carolina at Charlotte

2 What is Remote Sensing? Remote Sensing may be broadly defined as the collection of information about an object without being in physical contact with the object. -Floyd Sabins, Remote Sensing Principles and Interpretation *** For our purposes, remote sensing is the collection of information about the surface of the Earth and atmosphere by detecting reflected and emitted electromagnetic radiation from sensors aboard airplanes and satellites.

3 Remote Sensing Is. SATELLITES AND AIRPLANES ELECTROMAGNETIC SPECTRUM DISASTER MONITORING CHANGE DETECTION ESPIONAGE LAND USE MAPPING AND GIS

4 A remote sensing image is a map of the reflectance or emittance properties of an area on the Earth.

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6 Tropical Storm Fay, Yesterday

7 Katrina August 29, 2005

8 Superdome area New Orleans Quickbird image (2.4 m pixels) August 31, 2005

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10 Why is Remote Sensing Useful? A picture is worth a thousand words 1) Large spatial format can give a synoptic view; quicker than field reconnaissance with no temporal variations. 2) Can acquire data from poorly accessible and inaccessible regions. 3) Spectral range of sensors allows for collection of data in invisible wavelengths. 4) Raster format of images allows for detection of change over time.

11 1) A Synoptic View: The BIG Picture

12 Remote Sensing is accomplished without being in physical contact with observed objects (more to the point from a vantage point way, way up high) Terra satellite and AVIRIS instrument on U2 airplane

13 An image of the entire planet: GOES Image

14 SeaWiFS Data Global Biomass Electron micrographs (1000X) of dinoflagellate Ornithocercus magnificus and the diatom Asteromphalus Sparse desert vegetation and lush rainforest vegetation

15 Mapping Whole Continents Average vegetation, March 1-10, Brown: stressed vegetation that is less dense than normal. Green: vegetation that is more dense than normal MODIS data

16 Sea Surface Change from Normal

17 Mineral Exploration ASTER data Red: Ferric mineralization Ramon area, Negev Desert, southern Israel

18 CO concentrations over Malaysia Terra MOPIT Image CO (and smoke) from fires in Sumatra

19 Banda Aceh 2004 tsunami

20 Understanding planetary-scale systems and the new science of global change require global-scale data over time. You can take a whole Earth approach to studying processes. Global warming, melting of ice caps, urban sprawl, desertification, deforestation, ozone depletion studies of these benefit from the global picture that remote sensing provides.

21 2007: Smallest Ice Cap on Record

22 Satellite images are used to monitor the Antarctic ozone hole

23 2) Data can be acquired from poorly accessible and inaccessible regions Mt. Erebus Antarctica Mt. Erebus Hyperion sensor

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25 Two of Saddam Hussein s s palaces Presidential Palace Presidential Palace Quickbird MS Feb

26 Iran s s Nuclear facility at Natanz IKONOS satellite image of North Korea's No Dong missile test pad

27 Very Remote Sensing Hard to get to by car Jupiter s volcanic moon, Io

28 3) Information about the Earth s surface can be collected in invisible wavelengths

29 UV image from Apollo 16 landing site: atmosphere and aurora Oil spill image using UV sensor on an airborne platform. Oil is much more reflective than water in the UV.

30 Visible Light: Vegetation HRSC-AX image 0.2 m/pixel

31 Near IR: Vegetation

32 Grass or Astroturf? Visible image Near-IR image

33 Thermal Infrared AVHRR Visible and infrared images

34 Idaho / Montana Fires MODIS thermal bands (3.7 and 3.9 microns)

35 Thermal IR Chiliques volcano in Chile, Jan 6, 2002 ASTER Thermal IR ASTER Bands 1,2,3

36 Microwave (Radar) Until the mid-1990s some 1.2 million square miles of central Antarctica appeared ed on maps as blank white space because visible/near-ir satellites couldn t t see through clouds Radarsat: Antarctica

37 4) Raster format of images allows for detection of change over time 1 km x 1 km pixels

38 Riyadh, Saudi Arabia

39 Change Detection: Suburban Sprawl 1993 Image Red: 1994 Change Green: 1995 Change

40 Raster format allows you to measure precisely where change has occurred

41 Location, Location, Location... Location in geographic space is important in many professions: (What is the latitude and longitude of the forest fire? What is the area of a river s floodplain, and are there homes and businesses threatened by floods? Do the volcanoes in an area line up on a fault?) GIS and remote sensing are mapping technologies; they deal with spatial information. The Best Map is an Image (Erdas Imagine software slogan), and maps based on images.

42 Remote Sensors Measure Reflections or Emissions of Electromagnetic Radiation The way different materials reflect and/or emit EMR is determined by their chemical and physical properties. A remote sensing image is a map of chemical or physical properties. For example, dry soil reflects visible light more strongly than wet soil. Healthy maple tree leaves reflect near-ir light more strongly than drought-stricken leaves. An active volcano emits more thermal IR radiation than a dormant one. Different materials reflect and emit different amounts of light in different wavelengths.

43 Remote Sensing Images and Applications are Spatial and Spectral Spatial: location (latitude/longitude) of buildings in a flood plain area of trees (km 2 ) in a forest lost to deforestation area of a barrier island lost due to hurricane erosion total length (in km) of roads in Mecklenburg County Spectral: identification of different rock types around a volcano percentage of spruce trees affected by pine bark beetle locating areas on barrier islands with no dense vegetation that may be at risk for erosion identifying areas near old mines that could be targets for mining exploration or mine waste cleanup

44 Technology and Remote Sensing New tools: new applications are being found as technologies improve New sensors are being launched (like Terra, Aqua, Quickbird), have increasingly higher spatial and spectral resolution (<1 m/pixel satellites, hyperspectral sensors), computers are faster and hold more data (some hyperspectral images and GIS databases are huge!), processing software is better

45 Remote Sensing History

46 A Brief History of Remote Sensing 1830 s: Photography experiments 1800 s s and early 1900 s: cameras mounted on various platforms (pigeons, balloons, airplanes, kites)...for the synoptic big picture view 1847: Fizeau and Foucault show that IR and visible light share similar properties 1930 s: Philo Farnsworth invents the image dissector tube, the first commercially viable system for producing and transmitting an electronic image (Couch potatoes also benefit). 1956: Colwell s s research on plants with IR photography April 1, 1960: TIROS 1, first weather satellite, better hurricane warnings, Katrina would have been worse (Galveston) 1960 s: Evelyn Pruitt (Naval reasearch scientist) coins remote sensing 1967: ATS-3, First geostationary satellite for meteorology carries ITT imagers with tubes developed by Farnsworth

47 Galveston, TX, ,000-10,000 lives lost Hurricane Isabel, Sept GOES-12 IR

48 A Brief History of Remote Sensing, Continued May 1, 1960: Frances Gary Powers U2 shot down 1960: Corona ( Keyhole( Keyhole ) ) was launched 1962: Cuban Missile Crisis 1972: ERTS (Landsat( 1) launched, first Earth observation satellite for scientific use, 4-band 4 MSS sensor 1985: Landsat 5, workhorse of remote sensing, still operating 1987: AVIRIS first flown, airborne hyperspectral instrument 1990s: Global remote sensing studies are practical 1999: Landsat 7 and Eos Terra Launched Early 2000 s: IKONOS, Quickbird,, Orbview-3 3 launched, spy satellite (1 m or better panchromatic) resolution

49 Spy Satellite Technology Many advances had military origins Sputnik 1 launch in 1957 Corona image, 1966 Francis Gary Powers, 1960

50 Cuban Missile Crisis, 1962

51 NASA Planetary science also contributed to the development of remote sensing methods. Mariner 9 image of Mars Olympus Mons in 1971

52 Geotechnologies Spatial data technologies all overlap and benefit from each other GIS Remote Sensing GPS

53 Earth As Art Bahamas Landsat 7

54 Kamchatka volcano

55 Lena Delta, Russia