Copyright, 1998-2013 © Qiming Zhou

GEOG3610 Remote Sensing and Image Interpretation

Remote sensing and geographyRemote sensing and geography

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Remote sensing and geography

What is remote sensing?Development of remote sensingObservations of the Earth’s surfaceCommunication and data collection

systemsImage ProcessingUse of remote sensing in geography

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What is remote sensing?

Remote sensing is the acquisition of information about an object without physical contact.

It includes photographic and digital remote sensors.

Aircraft and satellites are major platforms for the sensors.

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What is remote sensing?

Observation of a target by a device separated from it by some distance

What is measured? “lights” or “colour” - to discuss later

How are the photographs and images created airborne and satellite data How can I use the images identifying things, interpretation, see the

change

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Remote sensing systems

Reference data

Pictorial

Digital

Visual

Digital

Sensing systems

Data products

Interpretation and analysis

Information products

Users

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Development of remote sensing

The term “remote sensing” was coined in the early 1960’s by geographers in the Office of Naval Research of USA to apply to the information derived from photographic and non-photographic instruments.

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Remote sensing prior to 1960

Aristotle (2300 years ago): “camera obscura”. 1839 - photographic process (Daguerre and

Niepce) - “daguerrotype”. 1859 - first known balloon photograph

(Tournachon - “Nadar”, France). Air photograph - developed for military

purposes. Between WW1 and WW2, civilian use of air

photographs.

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1860 picture of Boston Harbour

This 1860 picture of Boston Harbour is thought to be the first aerial photograph taken in the US. The exposure was made from a balloon at an altitude of about 365m above the ground

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Old air-borne platforms

Above: Stalwart pigeon photographers prepare to work. The tiny pigeon cameras were designed in 1903 and weighed about 70g. Right: Peering down a camera viewfinder from the open cockpit of a Curtiss Jenny, a flier practices the early techniques of aerial photography.

(Courtesy Strain and Engle, 1992)

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Airphoto – Hong Kong 1945

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Remote sensing since 1960

1960 - TIROS-I: the first meteorological satellite: low resolution sensor

1972 - ERTS-1 (changed to Landsat in 1975): MSS and HBV

1981 - NOAA: AVHRR 1982 - Landsat-4: TM 1986 - SPOT-1: PAN and XS since late 1980s: more earth observation

satellites, e.g. Russian, Indian, Japanese, Chinese and others

1999: IKONOS commercial ‘small’ satellites

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1960: TIROS-1

1960-1965

NASA/DOD

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1972: ERTS 1

Return beam vidicon (RBV) cameras

Data collection antenna

Multispectral scanner (MSS)

Solar array

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1981: NOAA

TIROS-N

1978-1981

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1982: Landsat 4

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1983: NOAA 8

Advanced TIROS-N (ATN)

1983-1994

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1986: SPOT 1SPOT - Système Pour l’Observation de la Terre - initiated by French government in late 1970’s.

SPOT 1: 21/2/1986SPOT 2: 21/1/1990SPOT 3: 23/9/1993SPOT 4: 26/3/1998SPOT 5: 4/5/2002

All currently operational except SPOT 3, which is recently lost (1997).

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Launched 1995 (Canada Space Agency)sun-synchronous, 793-821km orbit, repeat 24 daysSensor: C-band SAR

1995: Radarsat

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Terra is the first of the NASA’s Earth Observing System satellite series. It was launched in December 1999 and activated for science operation on 24 February 2000.

Courtesy terra.nasa.gov

1999: EOS-AM 1 (Terra Spacecraft)

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1999: IKONOS

The first ‘small’ satellite launched and operated by a commercial company (SpaceImaging)

Weight 1600 poundsLaunched on 24 September 1999Ground resolution:

Panchromatic: 1m Multispectral: 4m

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2001: QuickBird

Commercial remote sensing system developed and operated by DigitalGlobe

Launched on 18 October 2001Ground resolution:

Panchromatic: 61cm Multispectral: 2.44m

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Comparison of the two major periods in the history of remote sensing

Prior to the space age(1860-1960)

Since 1960

A. Only one kind and date of photography A. Many kinds and dates of remotesensing data

B. Heavy reliance on the human analysisof unenhanced images

B. Heavy reliance on the machine analysisand enhancement of images

C. Extensive use of photo interpretationkeys

C. Minimal use of photo interpretation keys

D. Relatively good military/civil relationswith respect to remote sensing

D. Relatively poor military/civil relationswith respect to remote sensing

E. Few problems with uninformedopportunists

E. Many problems with uninformedopportunists

F. Minimal applicability of the "multi"concept

F. Extensive applicability of the "multi"concept

G. Equipment simple and inexpensive;readily operated and maintained byresource-oriented workers

G. Equipment complex and expensive; notreadily operated and maintained byresource-oriented workers

H. Little concern about the renewability ofresources, environmental protection,global resource information systems,and associated problems related to"signature extension", "complexity of anarea's structure", and/or the threatimposed by "economic weaponry"

H. Much concern about the renewability ofresources, environmental protection,global resource information systems,and associated problems related to"signature extension", "complexity of anarea's structure", and/or the threatimposed by "economic weaponry"

I. Heavy resistance to "technologyacceptance" by potential users ofremote sensing-derived information.

I. Continuing heavy resistance to"technology acceptance" by potentialusers of remote sensing-derivedinformation.

Adapted from Colwell, 1983

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How does remote sensing work?

recording and measuring electromagnetic radiation from the target.

This recording and measurement can be taken by airborne or satellite sensors.

Remotely sensed images are rectified and enhanced to show information better.

We interpret the images to get information on given locations for mapping, management, etc.

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Observation of the earth’s surface

For geographers, we use remote sensing to observe the Earth’s surface.

Air photographs offer detailed view of the Earth’s surface but limited by many factors.

Satellite photographs and images provide less detailed but more variety of information with a large and regular coverage.

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Causes of differences in scale of aircraft and satellite observations

AircraftSatellite

Thousands of metres

Hundreds of kilometres

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Passive and active remote sensing

Passive remote sensing: the sensor detects the reflectance of sunlight from the surface e.g. photographs, multispectral

scannersActive remote sensing: the sensor

detects the reflectance of the signal sent by the remote sensing system e.g. RADAR

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Passive remote sensing

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Active remote sensing

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Communication and data collection systems

Remotely sensed data has to be transmitted back to the Earth.

A network of satellite receiving stations have been established over the world to receive data.

Some satellite data can be directly received by small instruments.

Data are available through variable commercial channels (e.g. EOSAT).

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Overview of data collection and platform location system

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Image processing

Digital images are the major types of today’s remotely sensed data.

They are fundamentally numbers. To make sense of them, a technology called

image processing is employed to distort, enhance and extract information from the images.

Image processing and interpretation are the focus for this subject.

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Use of remote sensing in geography

Remote sensing can bring us accurate, cheap and frequently updated information about the Earth’s surface.

GIS is the optimum tool to handle and integrate large amount of spatially referenced data including remotely sensed data.

Many things and phenomena in the real world are spatially referenced.

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Some examples of applications

AgricultureForestryEnvironmentUrban and regional planningMineral resourcesand many more...