Saturday, February 11, 2006

Cartography and Development

The NASA affiliated website Earth Observatory (EO) has some of the best images of Earth taken from space. These photos aren't just pretty pictures like the Aster Mexicali image at left; also check out this aerial of Rio de Janeiro!

On the development front, the Aiding Afghanistan section of the site talks about the efforts of the Famine Early Warning System Network (FEWS NET), who using maps, "works to avert famine, particularly in Africa, Central America, and Afghanistan." Amazing work. Contrary to what one might think about the need for high-resolution and detailed images of land, the work of remote ecologists is based on wide, low-resolution regional images.

"The images [...] produced are not like photos; they are a vegetation “index,” or scale, based on the kind of light reflected from the ground or vegetation surface in a region. Plant leaves absorb visible light for photosynthesis and reflect near-infrared light. If a satellite detects significantly more near-infrared light than visible light, the region is likely to be densely vegetated. By comparing the difference in intensity between visible and near-infrared light measured over crop areas in current imagery with the difference measured at the same time in past years, Tucker can tell how leafy a crop region is compared to normal. Plotting out the anomalies reveals where vegetation is thicker than normal because of good conditions or thinner than normal as a result of drought."


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