After a request for possible sources of high resolution satellite imagery to help with a planned fuel wood and landcover study in Darfur, I suggested contacting UNOCHA and UNMIS / UNAMID in Khartoum. This went with some provisos about the difficulty in detecting vegetation, spectrally, that is both sparse and tends to be light coloured, against a background of sand, soil and rock that also tends to be light coloured. As it happened, a few minutes later, I came across this paper, Developing a MODIS-based index to discriminate dead fuel from photosynthetic vegetation and soil background in the Asian steppe area. Although MODIS is coarse in its spatial resolution (250 metres), it is free, frequent (daily), and rapidly available. Indeed, its low resolution makes it suitable for studies of large areas. However, I am doubtful as to how accurate any vegetation detection will be, considering the ‘mixture’ within each pixel.
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