Introduction to Remote Sensing Dr. Hassan J. Eghbali.
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Transcript of Introduction to Remote Sensing Dr. Hassan J. Eghbali.
Introduction to Remote Sensing
Dr. Hassan J. Eghbali
• Course outline– Lectures for first part of session, practicals second part
• Course mark 70% for exam, 30% for write-up of final practical, to be handed in by the end of term (Weds Mar 23rd?)
– First week familiarise ourselves with lab PCs and sources of image data on the web
– Next 3 practicals 2 weeks each (expect you to spend time on this outside Monday session)
– Final practical (Classification): 3 weeks, write-up
Format of the course
Dr. Hassan J. Eghbali
• Books– Jensen, J. R. (2000) Remote Sensing of the Environment: An Earth
Resource Perspective, 2000, Prentice Hall, New Jersey. (Excellent on RS but no image processing, around £40 from Waterstones).
– Jensen, J. R. (2005, 3rd ed.) Introductory Digital Image Processing, Prentice Hall, New Jersey. (Companion to above, around £40 from Waterstones) BUT mostly available online at http://www.cla.sc.edu/geog/rslab/751/index.html
– Lillesand, T. M., Kiefer, R. W. and Chipman, J. W. (2004, 5th ed.) Remote Sensing and Image Interpretation, John Wiley, New York. (good all-round text-book around £35).
– Mather, P. M. (1999) Computer Processing of Remotely‑sensed Images, 2nd Edition. John Wiley and Sons, Chichester.
– Campbell, J. B. (1996) Introduction to Remote Sensing (2nd Ed), London:Taylor and Francis.
Course material
Dr. Hassan J. Eghbali
• Web– Tutorials– http://rst.gsfc.nasa.gov/Front/tofc.html– http://mercator.upc.es/nicktutorial/TofC/table.html– http://earth.esa.int/applications/data_util/SARDOCS/spaceborne/
Radar_Courses/– http://www.crisp.nus.edu.sg/~research/tutorial/image.htm– http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/fundam_e.html– http://octopus.gma.org/surfing/satellites/index.html– Glossary of alphabet soup acronyms!
http://www.ccrs.nrcan.gc.ca/ccrs/learn/terms/glossary/glossary_e.html– Other resources– NASA www.nasa.gov– NASAs Visible Earth (source of data): http://visibleearth.nasa.gov/– European Space Agency www.esa.int– NOAA www.noaa.gov– Remote sensing and Photogrammetry Society UK www.rspsoc.org
Course material
Dr. Hassan J. Eghbali
5
• Course outline– Lecture 1: Introduction to EO
– Lecture 2: Introduction to image processing (image display/enhancement) - practical 1
– Lecture 3: Introduction to electromagnetic spectrum
– Lecture 4: Image arithmetic: ratios and spectral indices - practical 2
– Lecture 5: EM spectrum and the atmosphere, plus angular info.
– Lecture 6: Information extraction: spatial filtering and classification - practical 3 (assessed practical)
– Lecture 7: Spatial, spectral, temporal resolution and tradeoffs
– Lecture 8: Orbits, swaths and coverage
– Lecture 9: Pre-processing stages and sensor scanning mechanisms
– Lecture 10: Applications plus recap
Format of the course
Dr. Hassan J. Eghbali
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• General introduction to remote sensing (RS), Earth Observation (EO).......– definitions of RS
– Why do we do it?• Applications and issues
– Who and where?
– Concepts and terms• remote sensing process, end-to-end
Lecture outline
Dr. Hassan J. Eghbali
7
The Experts say "Remote Sensing is...”• ...techniques for collecting image or other forms of data
about an object from measurements made at a distance from the object, and the processing and analysis of the data (RESORS, CCRS).
• ”...the science (and to some extent, art) of acquiring information about the Earth's surface without actually being in contact with it. This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information.”
http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/chapter1/chapter1_1_e.html
What is remote sensing?
Dr. Hassan J. Eghbali
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The not so experts say "Remote Sensing is...”
• Advanced colouring-in.
• Seeing what can't be seen, then convincing someone that you're right.
• Being as far away from your object of study as possible and getting the computer to handle the numbers.
• Legitimised voyeurism(more of the same from http://www.ccrs.nrcan.gc.ca/ccrs/eduref/misc)
What is remote sensing (II)?
Dr. Hassan J. Eghbali
Remote Sensing Examples•First aerial photo credited to Frenchman Felix Tournachon in Bievre Valley, 1858.
•Boston from balloon (oldest preserved aerial photo), 1860, by James Wallace Black.
Dr. Hassan J. Eghbali
Remote Sensing Examples
•Kites (still used!) Panorama of San Francisco, 1906.
•Up to 9 large kites used to carry camera weighing 23kg.
Dr. Hassan J. Eghbali
Remote Sensing Examples
Dr. Hassan J. Eghbali
Remote Sensing: scales and platforms
•Not always big/expensive equipment
•Individual/small groups
•Calibration/validation campaigns
Dr. Hassan J. Eghbali
Remote Sensing: scales and platforms
•Both taken via kite aerial photography•http://arch.ced.berkeley.edu/kap/kaptoc.html
•http://activetectonics.la.asu.edu/Fires_and_Floods/
Dr. Hassan J. Eghbali
Remote Sensing: scales and platforms
•Platform depends on application
•What information do we want?
•How much detail?
•What type of detail?
upscale
http://www-imk.fzk.de:8080/imk2/mipas-b/mipas-b.htm
upscale upscale
Dr. Hassan J. Eghbali
Remote Sensing: scales and platforms•E.g. aerial photography
•From multimap.com
•Most of UK
•Cost? Time?
Dr. Hassan J. Eghbali
Remote Sensing: scales and platforms
•Many types of satellite
•Different orbits, instruments, applications
upscale
Dr. Hassan J. Eghbali
Remote Sensing Examples
•Global maps of vegetation from MODIS instrument
Dr. Hassan J. Eghbali
Remote Sensing Examples
•Global maps of sea surface temperature and land surface reflectance from MODIS instrument
Dr. Hassan J. Eghbali
Remote sensing applications
•Environmental: climate, ecosystem, hazard mapping and monitoring, vegetation, carbon cycle, oceans, ice
•Commercial: telecomms, agriculture, geology and petroleum, mapping
•Military: reconnaissance, mapping, navigation (GPS)
•Weather monitoring and prediction
•Many, many more
Dr. Hassan J. Eghbali
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• Collection of data– Some type of remotely measured signal
– Electromagnetic radiation of some form
• Transformation of signal into something useful– Information extraction
– Use of information to answer a question or confirm/contradict a hypothesis
EO process in summary.....
Dr. Hassan J. Eghbali
Remote sensing process: IStatement of problem
•What information do we want?
•Appropriate problem-solving approach?
Formulate hypothesis
Hypothesis testing
•In situ: field, lab, ancillary data (Meteorology? Historical? Other?)
•EO data: Type? Resolution? Cost? Availability?
•Pre/post processing?
Data collection
•Analog: visual, expert interp.
•Digital: spatial, photogrammetric, spectral etc.
•Modelling: prediction & understanding
•Information extraction
Data analysis
•Products: images, maps, thematic maps, databases etc.
•Models: parameters and predictions
•Quantify: error & uncertainty analysis
•Graphs and statistics
Presentation of information
Dr. Hassan J. Eghbali
The Remote Sensing Process: II• Collection of information about an object without
coming into physical contact with that object
Passive: solar reflected/emitted
Active:RADAR (backscattered); LiDAR (reflected)
Dr. Hassan J. Eghbali
The Remote Sensing Process: III
• What are we collecting?– Electromagnetic radiation (EMR)
• What is the source?– Solar radiation
• passive - reflected, emitted
– OR artificial source• active - RADAR, LiDAR
Dr. Hassan J. Eghbali
Electromagnetic radiation?
•Electric field (E)
•Magnetic field (M)
•Perpendicular and travel at velocity, c (3x108 ms-1)
Dr. Hassan J. Eghbali
• Energy radiated from sun (or active sensor)• Energy 1/wavelength (1/)
– shorter (higher f) == higher energy
– longer (lower f) == lower energyfrom http://rst.gsfc.nasa.gov/Intro/Part2_4.html
Dr. Hassan J. Eghbali
Information
• What type of information are we trying to get at?
• What information is available from RS?– Spatial, spectral, temporal, angular,
polarization, etc.
Dr. Hassan J. Eghbali
Spectral information: vegetation
Wavelength, nm
400 600 800 1000 1200
refle
ctan
ce(%
)
0.0
0.1
0.2
0.3
0.4
0.5
very high leaf area
very low leaf area
sunlit soil
NIR, high reflectance
Visible red, low reflectance
Visible green, higher than red
Dr. Hassan J. Eghbali
Spectral information: vegetation
Dr. Hassan J. Eghbali
Colour Composites: spectral‘Real Colour’
composite
Red band on red
Green band on green
Blue band on blue
Approximates “real” colour (RGB colour composite)
Landsat TM image of Swanley, 1988
Dr. Hassan J. Eghbali
Rondonia 1975
Temporal information
Change detection
http://earth.jsc.nasa.gov/lores.cgi?PHOTO=STS046-078-026
http://www.yale.edu/ceo/DataArchive/brazil.html
Rondonia 1986
Rondonia 1992
Dr. Hassan J. Eghbali
when we view an RS image, we see a 'picture’ BUT need to be aware of the 'image formation process' to:
– understand and use the information content of the image and factors operating on it
– spatially reference the data
Always bear in mind.....
Dr. Hassan J. Eghbali
Remote Sensing:What is it and why do we use it?
• Many monitoring issues global or regional• Drawbacks of in situ measurement …..• Remote sensing can provide (not always!)
– Global coverage
• Range of spatial resolutions
– Temporal coverage (repeat viewing)
– Spectral information (wavelength)
– Angular information (different view angles)
Dr. Hassan J. Eghbali
33
• source of spatial and temporal information (land surface, oceans, atmosphere, ice)
• monitor and develop understanding of environment (measurement and modelling)
• information can be accurate, timely, consistent • remote access • some historical data (1960s/70s+) • move to quantitative RS e.g. data for climate
– some commercial applications (growing?) e.g. weather– typically (geo)'physical' information but information widely used
(surrogate - tsetse fly mapping)
– derive data (raster) for input to GIS (land cover, temperature etc.)
Why do we study/use remote sensing?
Dr. Hassan J. Eghbali
Caveats!
• Remote sensing has many problems– Can be expensive– Technically difficult– NOT direct
• measure surrogate variables
• e.g. reflectance (%), brightness temperature (Wm-2 oK), backscatter (dB)
• RELATE to other, more direct properties.
Dr. Hassan J. Eghbali