South Africa: The earth observation division of the South African National Space Agency (SANSA) released the latest edition of its mosaic of satellite imagery of the whole of South Africa, using data from the Spot 5 earth observation satellite. The dataset contains imagery, acquired during January 24 to December 20, 2011. It is known as the Spot 5 Mosaic 2011. The first Spot 5 mosaic of the country was compiled in 2006.
“The mosaic can be used for many purposes, which include housing and urban planning, agriculture (especially determining crop yields), water, and particularly, dam monitoring, environmental monitoring, forestry monitoring and so on,” stated SANSA Earth Observation production manager Natalie Diemer.
These images are 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 have been combined to create 476 2.5 m resolution true 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.
Merging of the two types of image to form the scene is done automatically. “But, sometimes, there is a glitch in the process,” said Diemer. “So every scene needs to be checked manually.”
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).
Source: Engineering News