200910 CEGEG046 GEOG3051 Principles

1
2009-10 CEGEG046 / GEOG3051Principles Practice
of Remote Sensing (PPRS)1 Introduction to
Remote Sensing

• Dr. Mathias (Mat) Disney
• UCL Geography
• Office 113, Pearson Building
• Tel [phone]
• Email mdisney_at_ucl.geog.ac.uk
• www.geog.ucl.ac.uk/mdisney

2

Format of the course

• Term 1
• Radiometric principles and data collection
  (Disney)
• Mapping science (Dowman, Iliffe, Haklay, Backes,
  Smith, Cross)
• Computing for image analysis (Lewis)
• Analytical methods (Ziebart, Iliffe)
• Image processing GIS (Liu)
• Organisations (Harris)
• Global Monitoring of Environment Security
  (Muller, Disney,Laxon etc.)
• Seminars (Thurs afternoons, 5-6 pm dates TBC,
  room 304 3rd floor Pearson BUT north entrance!)

3

Format of the course

• Term 2
• Advanced Modules
• Geomatics for coastal zone/Geomatics for ocean
  management (Oceans 2) (Simons, Morley, Iliffe)
• Topographic mapping/Terrestrial laser
  scanning(Dowman, Backes, Robson)
• Airborne laser scanning/Digital mapping (Dowman,
  Backes,Lewis)
• Renewable natural resources (Lewis, Wooster)
• Term 3
• Research project

4

Miscellaneous

• Remote Sensing and Photogrammetry Society
• http//www.rspsoc.org/
• 19 for students get 1 yr RSE for 83
• student meeting 10-11 Mar 2008, New Forest,
  organised by Tina Thomson from GE
• travel bursaries
• NERC National Centre for Earth Observation (NCEO)
• involvment in several themes at UCL
• Solid Earth (Centre for the Observation and
  Modelling of Earthquakes Tectonics) _at_ GE
  http//comet.nerc.ac.uk/
• NERC National Centre for Earth Observation (NCEO
  http//www.nceo.ac.uk/)
• Cryosphere (Centre for Polar Observation and
  Modelling) _at_ Earth Sciences http//www.cpom.org/
• Carbon Theme (formerly Carbon Centre for
  Terrestrial Carbon Dynamicshttp//ctcd.nerc.ac.uk)
  _at_ Geography

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Reading and browsing

• Remote sensing
• Campbell, J. B. (1996) Introduction to Remote
  Sensing (2nd Ed), LondonTaylor and Francis.
• Harris, R. (1987) "Satellite Remote Sensing, An
  Introduction", Routledge Kegan Paul.
• 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).
• Jensen, J. R. (2005, 3rd ed.) Introductory
  Digital Image Processing, Prentice Hall, New
  Jersey. (Companion to above) BUT mostly available
  online at http//www.cla.sc.edu/geog/rslab/751/ind
  ex.html
• Lillesand, T. M., Kiefer, R. W. and Chipman, J.
  W. (2004, 5th ed.) Remote Sensing and Image
  Interpretation, John Wiley, New York.
• Mather, P. M. (1999) Computer Processing of
  Remotely-sensed Images, 2nd Edition. John Wiley
  and Sons, Chichester.
• W.G. Rees, 1996. "Physical Principles of Remote
  Sensing", Cambridge Univ. Press.
• General
• Monteith, J. L. and Unsworth, M. H. (1990)
  Principles of Environmental Physics, 2nd ed.
  Edward Arnold, London.
• Hilborn, R. and Mangel, M. (1997) The Ecological
  Detective Confronting models with data,
  Monographs in population biology 28, Princeton
  University Press, New Jersey, USA.

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Reading and browsing

• Moodle www.geog.ucl.ac.uk/mdisney/pprs.html
• Web
• Tutorials
• http//rst.gsfc.nasa.gov/
• http//earth.esa.int/applications/data_util/SARDOC
  S/spaceborne/Radar_Courses/
• http//www.crisp.nus.edu.sg/research/tutorial/ima
  ge.htm
• http//www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/f
  undam/fundam_e.html
• http//octopus.gma.org/surfing/satellites/index.ht
  ml
• Glossary of alphabet soup acronyms!
  http//www.ccrs.nrcan.gc.ca/ccrs/learn/terms/gloss
  ary/glossary_e.html
• Other resources
• NASA www.nasa.gov
• NASAs Visible Earth (source of data)
  http//visibleearth.nasa.gov/
• European Space Agency earth.esa.int
• NOAA www.noaa.gov
• Remote sensing and Photogrammetry Society UK
  www.rspsoc.org
• IKONOS http//www.spaceimaging.com/
• QuickBird http//www.digitalglobe.com/

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Lecture outline

• 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

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What is remote sensing?

• 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/f
  undam/chapter1/chapter1_1_e.html

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What is remote sensing (II)?

• 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)

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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.

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Remote Sensing Examples

• Kites (still used!) Panorama of San Francisco,
  1906.
• Up to 9 large kites used to carry camera weighing
  23kg.

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Remote Sensing Examples
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Remote Sensing scales and platforms

• Not always big/expensive equipment
• Individual/small groups
• Calibration/validation campaigns

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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
  /

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Remote Sensing scales and platforms

• Platform depends on application
• What information do we want?
• How much detail?
• What type of detail?

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Remote Sensing scales and platforms

• E.g. aerial photography
• From multimap.com
• Most of UK
• Cost? Time?

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Remote Sensing scales and platforms

• Many types of satellite
• Different orbits, instruments, applications

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Remote Sensing Examples

• Global maps of vegetation from MODIS instrument

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Remote Sensing Examples

• Global maps of sea surface temperature and land
  surface reflectance from MODIS instrument

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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

21

EO process in summary.....

• 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

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Remote sensing process I
Formulate hypothesis
Hypothesis testing
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The Remote Sensing Process II

• Collection of information about an object without
  coming into physical contact with that object

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The Remote Sensing Process III

• What are we collecting?
• Electromagnetic radiation (EMR)
• What is the source?
• Solar radiation
• passive reflected (vis/NIR), emitted (thermal)
• OR artificial source
• active - RADAR, LiDAR

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Electromagnetic radiation?

• Electric field (E)
• Magnetic field (M)
• Perpendicular and travel at velocity, c (3x108
  ms-1)

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• Energy radiated from sun (or active sensor)
• Energy ? 1/wavelength (1/?)
• shorter ? (higher f) higher energy
• longer ? (lower f) lower energy
• from http//rst.gsfc.nasa.gov/Intro/Part2_4.html

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Information

• What type of information are we trying to get at?
• What information is available from RS?
• Spatial, spectral, temporal, angular,
  polarization, etc.

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Spectral information vegetation
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Spectral information vegetation
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Colour Composites spectral

• Real Colour composite

Approximates real colour (RGB colour
composite) Landsat TM image of Swanley, 1988
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Colour Composites spectral

• False Colour composite (FCC)
• NIR band on red
• red band on green
• green band on blue

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Colour Composites spectral

• False Colour composite
• NIR band on red
• red band on green
• green band on blue

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Colour Composites temporal

• False Colour composite
• many channel data, much not comparable to RGB
  (visible)
• e.g. Multi-temporal data
• but display as spectral
• AVHRR MVC 1995
• April
• August
• September

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Temporal information

• Change detection

http//earth.jsc.nasa.gov/lores.cgi?PHOTOSTS046-0
78-026 http//www.yale.edu/ceo/DataArchive/brazil.
html
35
Colour Composites angular

• False Colour composite
• many channel data, much not comparable to RGB
  (visible)
• e.g. MISR -Multi-angular data (August 2000)

0o 45o -45o
Real colour composite (RCC)
Northeast Botswana
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Always bear in mind.....

• 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

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Why do we use remote sensing?

• 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)

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Why do we study/use remote sensing?

• 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.)

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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.

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Colour Composites polarisation

• False Colour composite
• many channel data, much not comparable to RGB
  (visible)
• e.g. Multi-polarisation SAR
• HH Horizontal transmitted polarization and
  Horizontal received polarization
• VV Vertical transmitted polarization and
  Vertical received polarization
• HV Horizontal transmitted polarization and
  Vertical received polarization

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Back to the process....

• What sort of parameters are of interest?
• Variables describing Earth system....

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Information extraction process
After Jensen, p. 22
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Example Vegetation canopy modelling

• Develop detailed 3D models
• Simulate canopy scattering behaviour
• Compare with observations

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Output above/below canopy signal

• Light environment below a deciduous (birch) canopy

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LIDAR signal single birch tree

• Allows interpretation of signal, development of
  new methods

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EO and the Earth System
From Ruddiman, W. F., 2001. Earth's Climate past
and future.
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Example biophysical variables
After Jensen, p. 9
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Example biophysical variables
Good discussion of spectral information
extraction http//dynamo.ecn.purdue.edu/landgreb
/Principles.pdf
After Jensen, p. 9
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Remote Sensing Examples
Ice sheet dynamics Wingham et al. Science, 282
(5388) 456.
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Electromagnetic spectrum

• Zoom in on visible part of the EM spectrum
• very small part
• from visible blue (shorter ?)
• to visible red (longer ?)
• 0.4 to 0.7?m (10-6 m)

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Electromagnetic spectrum

• Interaction with the atmosphere
• transmission NOT even across the spectrum
• need to choose bands carefully!

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Interesting stuff..

• http//www.spaceimaging.com/gallery/zoomviewer.asp
  ?zoomifyImagePathhttp//www.spaceimaging.com/gall
  ery/zoomify/london_08_08_03/zoomifyX0zoomifyY0
  zoomifyZoom10zoomifyToolbar1zoomifyNavWin1l
  ocationLondon,20England
• http//www.digitalglobe.com/images/katrina/new_orl
  eans_dwtn_aug31_05_dg.jpg
• http//www.spaceimaging.com/gallery/tsunami/defaul
  t.htm
• http//www.spaceimaging.com/gallery/9-11/default.h
  tm