Image sources for informal settlement management

Informal settlements are a common feature of developing countries. In South Africa the improvement of living conditions in these settlements and the u pgrading to formal housing types are regarded as being of central importanc e to the nation's development. Effective settlement improvement and upgradi ng activities, which we here term "management", require adequate spatial da ta. To date, the acquisition of spatial models of informal settlements has been based on conventional mapping techniques, and mostly on photogrammetry . Data are compiled using analogue or analytical methods. These are manual and hence require both considerable expertise and expensive equipment. More over, these methods are uneconomical over the often relatively small, dense ly populated areas covered by informal settlements and are also too expensi ve to employ with a regularity required to support such tasks as change det ection. Alternative imaging sources and mapping techniques are therefore ne eded. In this article rye examine the problem of spatial information aquisition f or informal settlement management from three perspectives: spatial informat ion requirements, the role which imagery can play in satisfying these spati al information requirements, and effective imaging options. We focus on the potential of high resolution satellite imaging, small format digital aeria l imagery and digital multispectral video systems for rapid mapping. We als o discuss the example of automated shack extraction from aerial imagery.