http://www.engineeringnews.co.za
  SEARCH
Login
R/€ = 13.71Change: -0.01
R/$ = 11.01Change: -0.05
Au 1186.29 $/ozChange: -5.61
Pt 1214.50 $/ozChange: -5.00
 
 
Note: Search is limited to the most recent 250 articles. Set date range to access earlier articles.
Where? With... When?








Start
 
End
 
 
And must exclude these words...
Close Main Search
Close Main Login
My Profile News Alerts Newsletters Logout Close Main Profile
 
Agriculture   Automotive   Chemicals   Competition Policy   Construction   Defence   Economy   Electricity   Energy   Environment   ICT   Metals   Mining   Science and Technology   Services   Trade   Transport & Logistics   Water  
What's On Press Office Tenders Suppliers Directory Research Jobs Announcements Contact Us
 
 
 
RSS Feed
Article   Comments   Other News   Research   Magazine  
 
 
Mar 09, 2012

South Africa 2011 satellite imagery mosaic now available

Back
Agriculture|Africa|Astrium|Housing|Water|Africa|South Africa|Earth Observation Satellite|Final Product|Satellite Imagery|Environmental|Natalie Diemer|Water
Agriculture|Africa|Housing|Water|Africa|||Environmental|Water
agriculture|africa-company|astrium|housing|water-company|africa|south-africa|earth-observation-satellite|final-product|satellite-imagery|environmental|natalie-diemer|water
© Reuse this



The Earth Observation division of the South African National Space Agency (Sansa) recently launched the latest edition of its mosaic of satellite imagery of the whole of South Africa, using data from the Spot 5 earth observation satellite. Assembled from imagery taken and collected from January 24 to December 20 last year, it is known as the Spot 5 Mosaic 2011.

“The mosaic can be used for many purposes,” highlights Sansa Earth Observation production manager Natalie Diemer, “[like] housing and urban planning, agriculture (especially determining crop yields), water and, particu-larly, dam monitoring, environmental monitor-ing, forestry monitoring, and so on.”

More than 1 000 images were acquired over eleven months, most during winter when cloud cover is minimal over most of the country. “Cloud cover is always a problem,” she observes. Of these, 952 were used in the creation of the mosaic. These were composed of 476 multispectral (colour) images with a resolution of 10 m and 476 panchromatic (black and white) images with a resolution of 2.5 m. These were combined to create 476 2.5 m resolution colour scenes, which were “mosaicked” to create the image of the entire country. This was then divided into squares, called tiles, to produce the final product.

The merging of the two types of image to form the scene is done automatically. “But, sometimes, there is a glitch in the process,” says Diemer. “So every scene needs to be checked manually. My team does this.” The processing of the imagery started while the collection process was still under way. “The making of the mosaic is quite a big task,” she avers.

The processing of the imagery to what is called Level 3 B – the level required for the mosaic – took eight months, and involved orthorectification (positioning and elimination of distortion in the images), pansharpening (transforming lower resolution colour images into higher resolution colour images), true colour conversion, colour balancing, manual editing to reduce cloud cover and eliminate “no data areas”. The entire mosaic is supplied on a single disc, and is available in different formats – UTM, tiff (zipped); geographic, tiff (zipped); geographic JP2000 format, compressed; geographic, ecw format (zipped) and degraded to 10 m resolution, geographic, tiff (zipped).

“We send out about 30 discs,” she reports. Each province gets one, with the data for its territory; others go to the Presidency, govern-ment departments and government agencies such as South African National Parks.

In addition, Sansa Earth Observation sup-plies discs containing each scene separately and providing both the final scene and the two images that make it up. Each set comprises two discs. These are used for scientific research and are supplied, for example, to universities. About 15 such sets of discs are issued. Most images on these discs have been processed to Level 3 A quality, a process which took six months and included orthorectification, pansharpening and “lots of checking”.

The first Spot 5 mosaic of the country was compiled in 2006. “In 2006, the mosaic of the country had a lot of wide-angled images,” states Diemer. “[The year] 2011 was the first time that pretty much all the images were taken at a very narrow angle.” The narrower the angle, the better the positional detail revealed.

However, while, with the wide-angle images, the entire country was covered, with the narrow angle images, there are six small parts of the country that have not been covered. All of these are very small, indeed, amounting to gaps of less than 200 m2 in the coverage – the equivalent of a cloud. However, this will not be a problem as Sansa will be able to supply newer imagery of the areas concerned, should it be required.

Spot 5 was launched in 2002 and is operated by European space company Astrium. Spot is a French acronym: Satellite Pour l’Observation de la Terre (Earth observation satellite, in English). In terms of its licence from Astrium, Sansa can only supply the mosaic to government departments, agencies and universities.

Edited by: Martin Zhuwakinyu
© Reuse this Comment Guidelines (150 word limit)
 
 
 
 
 
 
 
 
Other Science and Technology News
DISCOVERING MATHEMATICS An effective teacher can make mathematics concepts accessible for children, enabling them to discover mathematics principles
Electronic engineering research and development company Keystone Electronics notes that many of the engineering graduate candidates it interviews lack a firm grasp of key foundational mathematical and scientific concepts. Keystone Electronics subjects candidates to...
FRANS JOHANSSON The only risk to companies’ sustainability is doing the same thing over and over
Logic alone does not confer a competitive advantage and companies must increase collaboration to capture latent potential innovations that will improve the business, says entrepreneurial and innovation consultant Frans Johansson. Expertise is not a sufficient...
The Space Science division of the South African National Space Agency (Sansa) is focusing its attention on space research in the South Polar region and in the upper atmosphere, with particular interest in phenomena called Transient Luminous Events (TLEs), but more...
More
 
 
Latest News
Barack Obama
Updated 9 minutes ago Barack Obama last year told a cheering crowd in Cape Town that a $7-billion plan to "Power Africa" would double electricity output on the world's poorest continent and bring "light where currently there is darkness". A year later, the US president's flagship project...
Updated 23 minutes ago There is widespread consensus that the Price Preference System (PPS) –introduced in September 2013 to restrict the export of scrap metal before it had first been offered for sale to the domestic consumers at a 20% discount to an international benchmark price – has...
Updated 33 minutes ago The Department of Agriculture, Forestry and Fisheries (Daff) has unveiled a draft version of the Agriculture Policy Action Plan (Apap), which is aligned with the National Development Plan’s (NDP’s) target of creating one-million agricultural-sector jobs by 2030. The...
More
 
 
Recent Research Reports
 
 
 
 
This Week's Magazine
As the City of Ekurhuleni continues its bid to develop the largely industrialised metropole into the continent’s first aerotropolis, executive mayor Mondli Gungubele has committed the city to creating a predictable, stable and enabling business environment in which...
While Ford Motor Company of Southern Africa (FMCSA) did not have “significant issues” with power supply in Gauteng, it was a different story in the Eastern Cape, said FMCSA and American Chamber of Commerce in South Africa president Jeff Nemeth earlier this month....
In 2000, exports into Africa from South Africa represented less than 5% of the turnover of Federal Mogul Motorparts Africa, with sales largely centred around Zimbabwe, Zambia, Malawi and Mozambique. Today, African exports represent 30% of sales, with trade expanded...
The Malawi government has launched a $50-million project to upgrade the Kamuzu barrage, on the Shire river, an outlet of Lake Malawi, which is used to control the flow of water from the lake to the lower Shire area. The project will run from this year to 2017 and...
  Our new Technical and Vocational Education and Training (TVET) Colleges will replace the Further Education and Training (FET) Colleges which have served us for the past twenty years.  The buildings will be the same and most of the staff will be the same but as the...
 
 
 
 
 
 
 
 
 
Alert Close
Embed Code Close
content
Research Reports Close
Research Reports are a product of the
Research Channel Africa. Reports can be bought individually or you can gain full access to all reports as part of a Research Channel Africa subscription.
Find Out More Buy Report
 
 
Close
Engineering News
Completely Re-Engineered
Experience it now. Click here
*website to launch in a few weeks