Foreword to the Special Issue on “Human Settlements: A Global Remote Sensing Challenge”

This special issue follows the one in June 2008 and is related to the very successful series of the Joint Urban Remote Sensing Events, held every two years since 2005. Remote sensing of urban areas is at the moment facing a rapid development, due to the increasing amount of High Resolution (UR) and Very High Resolution VHR (VHR) data in both the optical/IR and microwave regions of the electromagnetic spectrum. On a global scale, human settlements have always been the focus of interest, but only in these days there starts to be an interest in mapping and monitoring even small and informal ones by satellites. Coherently, urban area mapping is moving from basic land cover to more complex land use maps, and human settlement environmental monitoring is committed to a more and more integrated use of remote sensing and in situ data. By presenting excellent papers on these subjects, this special issue tries and provides an overview of the state-of-the-art in this interesting field of applied earth observation and remote sensing.