GEOGG141/ GEOG3051 Principles & Practice of Remote Sensing (PPRS) 1: Introduction to Remote Sensing Dr. Mathias (Mat) Disney UCL Geography Office: 113,

GEOGG141/ GEOG3051Principles & Practice of Remote Sensing (PPRS)1: Introduction to Remote SensingDr. Mathias (Mat) Disney

UCL Geography

Office: 113, Pearson Building

Tel: 7679 0592

Email: [email protected]

http://www2.geog.ucl.ac.uk/~mdisney/teaching/GEOGG141/GEOGG141.html

http://www2.geog.ucl.ac.uk/~mdisney/teaching/3051/GEOG3051.html

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• Component 1 (GEOGG141 only)– Mapping principles (Dowman, Iliffe, Haklay, Backes, Smith, Cross)– Understanding the geometry of data acquisition– Orbits, geoids and principles of geodesy

• Component 2 (GEOGG141 & GEOG3051)– Radiometric principles (Disney)– Understanding the what we measure and how– Radiative transfer (GEOGG141 only – Reading Week)– Resolution, sampling and practical tradeoffs– Pre-processing and ground segment– Active remote sensing (LIDAR, RADAR…)

Format

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• Remote Sensing at UCL– NERC National Centre for Earth Observation (NCEO)

http://www.nceo.ac.uk/) – Involvement in several themes at UCL

• Cryosphere @ Earth Sciences: http://www.cpom.org/ (Wingham, Laxman et al.)

• Carbon Theme @ Geography (Lewis, Mat Disney et al.)• Solid Earth: COMET @ GE http://comet.nerc.ac.uk/ (Ziebart)

– More generally• MSSL: http://www.ucl.ac.uk/mssl e.g. imaging (Muller), planetary, astro,

instruments

• UK prof. body - Remote Sensing and Photogrammetry Society– http://www.rspsoc.org/

Miscellaneous

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Reading and browsingRemote sensing

Campbell, J. B. (2006) Introduction to Remote Sensing (4th ed), London:Taylor and Francis.Harris, R. (1987) "Satellite Remote Sensing, An Introduction", Routledge & Kegan Paul.Jensen, J. R. (2006, 2nd ed) Remote Sensing of the Environment: An Earth Resource

Perspective, 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 some available online at http://www.cla.sc.edu/geog/rslab/751/index.html

Jones, H. and Vaughan, R. (2010, paperback) Remote Sensing of Vegetation: Principles, Techniques, and Applications, OUP, Oxford. Excellent.

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. (2004) Computer Processing of Remotely‑sensed Images, 3rdEdition. John Wiley and Sons, Chichester.

Rees, W. G. (2001, 2nd ed.). Physical Principles of Remote Sensing, Cambridge Univ. Press.Warner, T. A., Nellis, M. D. and Foody, G. M. eds. (2009) The SAGE Handbook of Remote

Sensing (Hardcover). Limited depth, but very wide-ranging – excellent reference book.GeneralMonteith, 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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• Moodle & www.geog.ucl.ac.uk/~mdisney/pprs.html• Web• Tutorials• http://rst.gsfc.nasa.gov/• http://earth.esa.int/applications/data_util/SARDOCS/spaceborne/Radar_Courses/• http://www.crisp.nus.edu.sg/~research/tutorial/image.htm• http://ccrs.nrcan.gc.ca/resource/index_e.php#tutor• http://octopus.gma.org/surfing/satellites/index.html

• Glossary : http://ccrs.nrcan.gc.ca/glossary/index_e.php

• Other resources• NASA www.nasa.gov• NASAs Visible Earth (source of data): http://visibleearth.nasa.gov/• European Space Agency earth.esa.int (eg Image of the week….)• NOAA www.noaa.gov• IKONOS: http://www.spaceimaging.com/• QuickBird: http://www.digitalglobe.com/

Browsing

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• General introduction to remote sensing (RS), Earth Observation (EO).......– definitions of RS– Concepts and terms

• remote sensing process, end-to-end

• Radiation I– Concepts and terms

• remote sensing process, end-to-end

Today

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The Experts say "Remote Sensing (RS) is...”• “The science technology and art of obtaining information

about objects or phenomena from a distance (i.e. without being in physical contact with them”

http://ccrs.nrcan.gc.ca/glossary/index_e.php?id=486

• But not the whole story:– Tend to use Earth Observation (EO). To distinguish from?– Domains (atmosphere, terrestrial, ocean, cryosphere,

biosphere etc)– But also astronomy, planetary remote sensing etc.

What is remote sensing?

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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)?

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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

• 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?

upscale

http://www-imk.fzk.de:8080/imk2/mipas-b/mipas-b.htm

upscale upscale

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Remote Sensing: scales and platforms

• Many types of satellite

• Different orbits, instruments, applications

upscale

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Remote Sensing Examples

• Global maps of vegetation from MODIS instrument

IKONOS-2 image of Venicehttp://www.esa.int/esaEO/SEM44R0UDSG_index_1.html

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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

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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.....

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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)

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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 energyfrom 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

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

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Spectral information: vegetation

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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

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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’ compositeNIR 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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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

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Colour Composites: angular

‘False Colour’ composite• many channel data, much not comparable to RGB (visible)

– e.g. MISR -Multi-angular data (August 2000)

Real colour composite (RCC) Northeast Botswana

0o; +45o; -45o

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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.....

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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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• 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?

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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

Image interpretation

• Tone, colour, stereo parallax

• Size, shape, texture, pattern, fractal dimension

• Height/shadow

• Site, association

Primary elements

Spatial arrangements

Secondary elements

Context

Analogue image

processing

• Multi:• spectral, spatial,

temporal, angular, scale, disciplinary

• Visualisation

• Ancillary info.: field and lab measurements, literature etc.

Presentation of information

• Multi:• spectral, spatial,

temporal, angular, scale, disciplinary

• Statistical/rule-based patterns

• Hyperspectral

• Modelling and simulation

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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.

External forcing

Hydrosphere

Atmosphere

Geosphere

Cryosphere

Biosphere

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Example biophysical variables

After Jensen, p. 9

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Example biophysical variables

After Jensen, p. 9

Good discussion of spectral information extraction:

http://dynamo.ecn.purdue.edu/~landgreb/Principles.pdf

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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 ~0.7m (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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• http://www.spaceimaging.com/gallery/zoomviewer.asp?zoomifyImagePath=http://www.spaceimaging.com/gallery/zoomify/london_08_08_03/&zoomifyX=0&zoomifyY=0&zoomifyZoom=10&zoomifyToolbar=1&zoomifyNavWin=1&location=London,%20England

• http://www.digitalglobe.com/images/katrina/new_orleans_dwtn_aug31_05_dg.jpg

• http://www.spaceimaging.com/gallery/tsunami/default.htm

• http://www.spaceimaging.com/gallery/9-11/default.htm

Interesting stuff…..