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RTD info logoMagazine on European Research N° 42 - August 2004   
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SATELLITE PICTURES
Title  What on earth …?

Demography, living standards, hygiene and sanitation, loss of biodiversity, over-exploitation of agricultural land and forests… all is revealed when you view the Earth from the heavens. Scientists and experts use these satellite pictures all the time in their work. Now, thanks to the PlanetObserver team, a much wider public should soon be benefiting from this magnificent geographical tool. This development project – supported by the EUREKA initiative – used advanced computer processes to develop the harmonisation and colouring techniques which make these unique documents so impressive, both for their beauty and their clarity.

In Clermont-Ferrand, the small regional capital of France’s Massif Central, surrounded by the volcanoes of the Auvergne, 27-year-old geologist Laurent Masselot founded the company M-SAT.(1) That was in 1989 and today orbiting satellites have been sending back fascinating images of the Earth’s surface for over a decade. ‘Seen from the sky, our planet is simply splendid and I believed that these pictures could be appreciated by a great many people. But to do that the very technical images studied by researchers and other experts would have to be used differently. To reach a wider public and motivate teachers, journalists and local or regional officials, the visual representations would have to impress with their beauty as well as their realism.’(2)

Triple know-how
Laurent Masselot and his team set about developing a triple know-how. The initial, fundamental stage is a process known as mosaicking. This involves assembling several dozen or even several hundred high-resolution satellite images of a precise area in digital form. Most of these pictures are obtained by Landsat 5, orbiting the Earth at an altitude of 705 km, a distance which makes it possible to view quite small areas of land with great precision. But other images, from the Spot, Cosmos or Noaa satellites, are also used as required.

Mosaicking is very painstaking work. It involves ‘merging’ on the same scale pictures of different segments of the same area but taken at different times and under different meteorological conditions. Distortion caused by the curved surface of the earth must be corrected and adaptations made in line with the scene portrayed – towns, farmland, coastal areas, mountain ranges, etc.

The next stage is realism in processing the colours. The aim is to obtain results which are both perfectly homogenous and geographically significant. ‘Clearly all the oceans are generally blue, the forests are green and the deserts beige. But these colours must be finely shaded in line with the specific nature of the location. The computer technology we developed permits a unique coloration, carried out on the three RGB channels, i.e. the red, green and blue values of each image pixel, while at the same time taking into account the filtering caused by the atmospheric layer when the photo is taken. To give you some idea of the processing involved, it should be remembered that a Landsat 5 picture provides on average one pixel every 30 metres, thus hundreds of millions of data for a single ‘raw’ picture.’

Finally, the pictures are also reworked using altimetric files supplied by digital models of the field which give its altitude at each point and enable the realistic reconstitution of 3D landscapes. 

Ploughing back the profits
PlanetObserver adopted a commercial development strategy whereby each image produced and marketed gives rise to a new and more ambitious product. ‘Fifteen years ago, we started with the Auvergne, our home base, then we set to work on France on the basis of a 40-picture mosaic. That marked the beginning of a degree of recognition, when this product was purchased and published in the prestigious magazine Geo in 1994. Other countries then followed, before culminating in 1996 in Europe with 250 images.’

The profits from the Europe product were immediately reinvested. ‘We then acquired 450 images which enabled us to cover the United States, which was mapped in 1998. The result was published by the Smithsonian Institute’s official journal and gave rise to an agreement with National Geographic.’ Next came a map of Asia (1 000 images covering 13 countries, including China, North and South Korea, and Japan). 

The ultimate ambition of this French firm was literally to ‘go global’. In the late 1990s, it was already looking at ways of developing its current flagship product, known as Terra Cognita©. The aim is to produce a perfectly homogenous mosaic of over 7 000 raw satellite pictures covering the Earth’s total land surface area. This project (3) was awarded a EUREKA label, in partnership with the Earth Sciences Laboratory of the Lyons Ecole Normale Supérieure and the Belgian SME Ionic Software which specialises in software designed for the processing of satellite images. 

A dream in the making
A product with a potentially global market, Terra Cognita has been operational since 2003. The database of this absolute geographical reference contains, as expected, around 7 000 pictures representing a collection of 2 000 billion pixels. In addition to the sheer visual pleasure provided by this fascinating mirror of the Earth’s surface, this innovative tool in mapping the entire planet has numerous practical applications, ranging from education and environmental information to sustainable development and geopolitics. Last year, Terra Cognita was the subject of an open-air exhibition at the foot of the Eiffel Tower (see pictures).

But Laurent Masselot has another dream now – that of one day ‘projecting our planet’ on to an area measuring 400 metres by 800 metres – thus 32 hectares – to obtain an image on the scale of 1/50 000. ‘In just 200 metres you would cross the Pacific, travelling from New Guinea to Peru. Using this huge photograph of the Earth it would be possible to observe all the mountain ranges, lakes, forests, cultivated areas and cities which cover its surface and follow all the roads and rivers which cross it. Don’t you think there is going to be a public interested in that?’   

(1) M-SAT was later renamed PlanetObserver.
(2) All quotations are by Laurent Masselot.
(3) Under the name Planet 2000.

The Earth is not only beautiful
Its appearance provides a wealth of information on its status and that of its inhabitants. At the 2003 exhibition at the Eiffel Tower in Paris, around 60 pictures of every continent were assembled on the basis of four themes: man, energy, the Earth and water. The photographs on this page, in no particular order this time, are taken from this PlanetObserver exhibition.

Lighting up Europe’s skies

© MSAT-PlanetObserver.com

© MSAT-PlanetObserver.com
The socio-economic status of the world is ‘glaringly obvious’ when viewed from the sky. At night, a ‘blue banana’ crosses Europe from Lancashire to Tuscany, passing through London, Brussels, Paris, Frankfurt, Stuttgart, Berne and Milan. Tiny Belgium is distinctive for its lit motorways which are well known to astronauts. A little off-centre are the urban areas of Birmingham, Madrid, Rome, Berlin, Warsaw, Oslo and St. Petersburg. Moving down to North Africa, the Sahara is in darkness, the only lights coming from the coastal towns and a few oases. 


Borneo – Indonesia

In the south of the island, the rivers Kapuas, Barito and Kutai flow into the sea. Their red colour is due to the presence of minerals and organic matter in suspension in the water. Over time, these sediments accumulate and give rise to vast marshy plains. The delta gradually fills up and widens. Mangroves then develop in these areas where the freshwater and salt water mix. The twisting trees, with their roots emerging from the water, attract birds, fish and monkeys. In the country’s interior, the very dark green colour indicates the density of the tropical forest which is home to about 500 species of trees. But the past two decades have brought deforestation. The cleared areas are shown in light green, almost yellow, criss-crossed by a network of drainage canals branching off from the river. The areas where the soil is bare are shown in red. In the medium term, all these changes risk destroying this exceptional ecosystem.   
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com


The relentless drying up of the Aral Sea

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com

This landlocked sea is in fact an expanse of freshwater shared by Kazakhstan, Turkmenistan and Uzbekistan. In 1960, the Aral Sea was the world’s fourth largest lake. Since then it has lost 60% of its water as a result of water being pumped from the rivers which feed it to irrigate the cotton fields and rice paddies. This process has increased the concentration of mineral salts in the lake, decimating the fish and completely eliminating fishing. The exposed areas are then eroded by the wind which sweeps away particles rich in salt. This is then deposited on arable farmland, reducing yields and causing farmers to increase the use of fertilisers and pesticides.

Amazonian forest – Brazil

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
The same place, seen in 1990 and in 2000. The clear areas show deforestation. The geometry is simple: a main road with side roads running perpendicular to it. The white spots are rural villages. There is no replanting. As the soil grows poorer the biodiversity suffers. The fallow land is given over to cattle to produce ‘hamburger beef’ for export.  


Antarctica – the greenhouse effect and melting ice

A flotilla of icebergs has broken away from the icecap and is seen drifting on the Weddell Sea. Some of them are 2 km wide. In addition to the melting during summer, when sections of the ice sheet break away, recent years have witnessed a constant and significant decrease in the thickness of the ice. This is due to the warming of the Earth’s atmosphere as a result of the growing greenhouse effect. The increase in sea levels caused by the melting of the glaciers could be as much as 50 cm, which means the Netherlands could lose 6% of its land and Bangladesh as much as 17%.  
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com


Pearls of the Pacific

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
The Great Barrier Reef stretches for 2 000 kilometres off the north-east coast of Australia. This coral reef has been progressively built up over 18 million years by billions of tiny primitive animals which bequeath their calcareous skeletons to it when they die. There are more than 400 species of coral in an area which is home to 1 500 species of fish and crustaceans. This source of life and protective barrier against the waves is now under threat on several fronts. Fishing using explosives and cyanide, trade in coral, the warming of the seas, pollution, tourism and underwater activities are all damaging the coral. Today, 58% of the world’s coral reefs are threatened by human activities.


Calcutta – an unwanted cloud

The city has a population of 3 million and infrastructure and housing for only 1 million. Around 200 000 people live in the street while others cram into bustees, built on low-lying land which floods during the monsoon. The greyish vertical cloud at the centre of the picture, along the clear river, shows the air pollution. The concentration of particles in suspension (smoke, soot, dust, droplets released by combustion, etc.) is 375 micrograms/m3. The WHO has set the limit at under 90 micrograms/m3 (Paris is at 14 and New York at 61).
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
 


Jezirah Plain – Sudan



© MSAT-PlanetObserver.com

© MSAT-PlanetObserver.com
In Sudan, the grasslands of the Jezirah (‘island’ in Arabic) stretch between two rivers: the White Nile (the snaking green on the map) and the Blue Nile. The river waters are used to cultivate plots of farmland (green rectangular areas). The fields of sesame, groundnuts, cotton and acacia gum follow the lines of the irrigation channels. Most of the population live in this region which covers 750 000 hectares. On the other side of the river, on the left, the pale area is the Libyan desert. 


Taklimakan Desert – China

The vastness of this desert is reflected in its name – ‘Once you have entered it, you will never leave it’. It is so hot that it is also sometimes known as the ‘sea of death’. The sand temperature can reach 70°C and the air temperature 50°C, dropping back to 20°C at night. The winds are strong and frequent. These conditions explain why the river on the photograph is only a temporary one. This hostile environment could, however, be made slightly more hospitable. Chinese geologists have discovered a huge underground lake which could be used to solve the cruel problem of water shortages which affect 10 million people in this region.
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com


Koufra oasis – Libya

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
The town is shown in blue. The airport appears as a geometric pattern, while the series of fields are circular. Within the desert, the oasis has been developed by capturing large areas of underground water. The water is pumped up and the earth is watered using mechanical arms pivoting on a central axis. It is this method which has caused the circular shape of the cultivated land. But this is not an inexhaustible resource – some experts believe that the groundwater will be exhausted within 50 years. 


Tropical forest – Democratic Republic of Congo

The deep green of virgin forest is etched with the branches of rivers, tributaries of the River Congo (formerly the Zaïre). On closer inspection, the green is not uniform – lighter marshy areas can be seen. In the top left there is a rectilinear network: the routes traced out for deforestation. In the deforested areas (salmon coloured) virtually nothing will grow because the soil, into which the water has cut deep gulleys, is becoming infertile.
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com


Delta of the River Betsiboka – Madagascar

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
This picture, taken in the north-east of the island, shows the impoverishment of the soils after deforestation. When there are fewer plants, and therefore fewer roots, the rainwater can leach nutritional elements from the soil. The powerful River Betsiboka washes away considerable quantities of suspended alluvium, recognisable by its reddish colour. The delta is made up entirely of deposits of this sediment. The consequences are all the more serious due to the strength of the river and the scale of the deforestation. 


Rub Al khali Desert – Saudi Arabia

‘Al khali’ means ‘the great emptiness’. Shaped and driven by the wind, the very red sand dunes move across a claylike soil (in blue). The white areas are crusts of salt. These colours indicate that a sea was once present here, during the primary era, which then evaporated to leave this mixture of clay and salt. This desert supports no vegetation or inhabitants, although agriculture would be possible if water was pumped up from below ground, as happens in Riyadh, the Saudi capital. 
© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com


Chengdu 1992-2000 – population growth

© MSAT-PlanetObserver.com
© MSAT-PlanetObserver.com
Taken at a decade’s interval, these two views of the capital of Sichuan Province, which lies in south-west China in a region known as the ‘land of plenty’, bear witness to the city’s power to attract rural dwellers seeking work. It is just one of many examples of urban growth. The population in cities could double by 2025 to reach 5 billion, or 6 out of 10 of the world’s population. 

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