Earth from Space

Earth from Space

Geography 250

Unit1,2 Introduction and Brief History

Earth Rise Dec 24th 1968 (while orbiting the moon)

"the most influential environmental photograph ever taken”

Course Aims

• Understand what we can learn about earth from data obtained from instruments in air or space

• To explore remotely sensed data such that you can select products that aid you in solving problems within the GIS environment

• Understand images that you see in the news

Earth from a Distance

• More difficult for the flat earth society!

• Earth as being visually conveyed– Uniqueness (so far!)– Water/Earth– Dynamic surfaces– Remote view as providing information to many

people including geographers

Remote Sensing

• Remote: from a distance

• In contrast to: In-situ - on site and in contact

• Sensing: some type of detection - data are obtained and stored

• Remote sensing “ the science, technology and art of obtaining information about objects from a distance”

Remote sensing capabilities

• Access to otherwise inaccessible areas– Antarctic, volcanoes, war zones, deep sea, disaster

areas, eg Katrina, (flooding shown here)

• View at a different scale– Patterns emerge not seen from the ground eg.

archaeological sites and hemispheric meteorological data from satellites

Remote sensing capabilities(Cont)

• Information from wavelengths other than visible

• We see a very narrow range of wavelengths

Information from other wavelengths

Wavelengths both outside of and within visible are assigned different colors such that the image can be readily interpreted

This image shows sea surface temperature from AVHRR

Other wavelengths

A wildfire in Yellowstone shown in visible light (left) and thermal IR imaging (right)

Remote sensing capabilities (Cont)• Cost effective for large areas• Aids in visualization

Remote sensing capabilities (Cont)

• Analysis over time• Air photos are

commonly used for map updates

• Images show sea surface height relative to an average sea surface height

Geography

• Geo/graphy = Earth/writing or Earth/description• Study of the distribution of physical and human

phenomena, their interactions and the reasons for their location.

• A study of where things are and why.• Hence remotely sensed data ‘fits’ into this area

of study as does GIS

Geographic Information Systems (GIS) 

• Automated overlay/combination of types of data.

• Technology used to answer questions such as:– Where is the best routing for a new power line,

place for a new store, controlled forest fire burns, conservation area, emergency management

• Software package such as ARCINFO• Geographic data:

• Remotely Sensed data and analysis of these data• Maps• Surveys eg census data• Point measurements (at known locations using GPS)

GIS

http://www.wiley.com/college/strahler/0471480533/animations/ch03_animations/animation4.html

Very early remote sensing

Battle in 1297

Drawings were made from hill-tops, trees, ship masts etc

Early remote sensing

• 1859 French Photographer and Balloonist Gaspard Felix Tournachon, also known as Nadar

Photo from a balloon anchored in Boston, made in 1860

(first photograph was in 1820s but cameras only became practical in the 1860s)

Photography from Kites• Composite photo of part of San Francisco

following the 1906 earthquake • Made from a camera on a kite

The Bavarian Pigeon Corps 1903Small light weight cameras were attached to the birds and a timer was set to take pictures ever 30 seconds as it flew. (Birds had been used for some time for messages)

Graflex camera used in WWI‘There were several aircraft used for aerial reconnaissance throughout the war. First made of wood and then metal, the aircraft was the focus of intense development. At the same time camera systems and techniques for measuring and identifying features on the ground were being developed. These interpretation and measurement techniques, and the men and women who practiced them during war time, continued after the war and applied them to other areas such as forestry and agriculture.’

WWI 1913 - 1918

Air photos played a major role in the war starting in 1915

Role of interpreters: Detectives

Use of clues: Convergence of information (Data fusion)Repeat photographs

Non-military applications

• Photogrammetry evolved: technology involved in making accurate measurements of distances and heights from maps

• Uses: Topographic maps, forest inventory (amount and type of trees), geologic mapping, agricultural statistics (who was growing what)

• Canada as mounting a comprehensive air photo campaign

• 1935 American Society of Photogrammetry formed (now also remote sensing) importance of this???

World War II (start 1939)

• Germans started out in the lead with the recognition of the importance of remote sensing.

• Had images of key sites in other countries• Also very good maps in the Baedeker guides and used

them in the invasion of Norway and Britain, term “Baedeker raids”

• 'We shall go out and bomb every building in Britain marked with three stars in the Baedeker Guide.' - Baron Gustav Braun von Sturm, 24 April 1942

World War II RAF air photo interpretation• ‘A group of British and American air photo interpreters work at the large

Medmenham interpretation center located near London, England. Air photo interpretation developed into a top priority program by 1943. Air photos were used to confirm or deny reports from spies in Europe

WWII developments

• New films – color infrared, able to tell vegetation from cloth painted green

• Radar- new wavelength, ‘see’ in the dark and in fog

Post-WWII

• 1950 – 1970• Continuing world tension, hence development• Many qualified photo interpreters with ideas of

the usefulness of technology• Color infrared declassified• Also multispectral imagery• Thermal Infrared• Side looking airborne radar

Color infrared AKA Near Infrared• Reflected energy at wavelengths a little

longer than what we can see (0.7 – 1.5 micrometers)Photography captures the green, red, and near-infrared energy, which is displayed in a false-color form

Color-infrared images are particularly useful for analysis of vegetation cover.

Active vegetation appears bright red and pink in color-infrared photographs. Other materials--bare soil, pavement, water--are depicted in green and blue colors. Study example: www.emporia.edu/nasa/epscor/ft_leav/epscor.htm

http://www.ars.usda.gov/Main/docs.htm?docid=8829

Thermal Infrared

Thermal infrared (thermal IR) is emitted energy, range 5.6micrometre to 1.0 cm

The waste heat from electrical generating stations is transferred to cooling water obtained from local water bodies such as a river, lake, or ocean.

The water is subsequently returned to the water body with a temperature higher than the ambient water temperature.

A thermal plume from a cooling station

Airborne Radar

Sensor emits microwaves and then receives microwaves that are returned to the sensor

Hence can image through fog!And darkness

Brazilian rain forest

Continued military• Higher resolution• Flights by the U-2 an ‘untouchable’ aircraft for four

years until 1960 when it was shot down (very embarrassing for the US).

• Space as the answer!• Corona as the first operational space photo

reconnaissance satellite (1960 – 1972)

Corona image of the Pentagon

Corona as secret until 1992

U-2 with Side Looking Airborne Radar (SLAR)

Information from the U-2 program

• Photo of a Soviet missile site in Cuba

Sputnik

• Oct 1957 - First satellite put into orbit around Earth! (lasted 3 months)

• USSR

• Fear – response was the ‘Space Race’

• http://www.sputnikmania.com/

Space as the answer!

Corona image of the Pentagon

Corona as secret until 1992

Corona satellite film recovery sequence

Non-military space imaging

• Weather satellite: TIROS-1

Before this the only information was from the ground and weather ships

Earth remote sensing an offshoot of moon exploration

1968 Apollo 8 lunar orbit

1969: Apollo 11 lunar landing

Interest in space coincided with growing concern about Earth

Satellites and earth observation 1972 - 1986

• Landsat 1972 and onwards

• Growing concern about human impact

• NASA program

First Landsat images

Landsat images of the Philippines

Thematic Mapper• Instrument on some of the later

Landsat satellites• Bands (segments of the spectrum) are

combined• These are known as multispectral

images • Called a thematic mapper because the

data can be used to map specific things like vegetation types, minerals

• Earlier version of the instrument was known as a multispectral scanner (MSS)

Advanced Very High resolution Radiometer (AVHRR)

• Another major earth observation program (initially intended for atmospheric information)

• NOAA 1.1 km resolution imagery• Visible and near IR

Vegetation using the near IR bands

Total Ozone Mapping Spectometer (TOMS)

Measurement of the ozone hole over the Antarctic (observations started in 1978?)

Radarsat• Canada/USA satellite for earth observation, launched in 1995• With time countries other than the US have become involved in

remote sensing, Canada, Europe, Japan, Brazil etc

Photographs vs digital images• Photographs: Light falling on a sensitive surface

(film)• Digital images: pixels, each of which has a

numerical value• Image processing initially lagged behind

acquisition• Digital images are replacing photographs• Why

– Amount of information

– Computer analysis

Digital images

• Like mosaics• Resolution in part a function of pixel (picture

element) size• Each pixel can have a value from 0 - 254

Orthophotos (a type of photo)Used for watershed and other land use planning, many uses

Photographs have been geometrically corrected ("orthorectified") so the scale of the photograph is uniform

Hence the photo can be considered equivalent to a map

Ortho images are often mosaics of orthophotos

These can be readily used in GIS

Beyond NASA and NOAA: Commercial programs

• IKONOS in 1999 (Space Imaging Inc/USA) – One-meter resolution– Multispectral and panchromatic (like b/w film)

• EROS A1 in 2000 (ImageSat/Israel&USA)

• Rapidly followed by others … increasing spatial resolution

• List: http://en.wikipedia.org/wiki/List_of_Earth_observation_satellites

Remote Sensing and GIS

• Complementary technologies– Talk to Ron Raty if you are interested in GIS

• Remotely sensed data are used in GIS systems in planning and also for Earth Science research

• This course focuses on remote sensing and what we can learn about Earth from various types of imagery.

Complementary nature

• Remotely sensed data: rich source of data• GIS powerful tool for analysis and display• “Integrating these technologies has been a

challenge” • Only in late 1990s was it possible for GIS

systems to ingest larger raster images• Geomatics: new field that includes surveying,

use of GIS, GPS, remote sensing, cartography (term coined in about 1970)

Global Positioning System (GPS)

Two part system:

• Satellites orbiting earth

• Handheld receivers

GPS

• Developed by the United States Department of Defense

• Officially called NAVSTAR GPS (NAVigation Satellite Timing And Ranging Global Positioning System).

• Provided for free to the public.

GPS

The Global Positioning System is based on a "constellation" of satellites that emit timed signals. Developed as a navigation (and weapons guidance) aid, GPS is now used as a very precise surveying tool. Under good conditions (and repeated fixes over several days), sites can be located within 2 cm.

(http://earth.leeds.ac.uk/dynamicearth/plates_move/active_tectonics/gps.ht)

http://www.youtube.com/watch?v=wi_3XwkA8cQ&feature=related

Remote sensing makes use of different wavelengths

Microwaves are about 1mm - 1m long.Radio waves are about a meter to 1000 meters long.