Global trends in remote sensing of human settlements

Advances in both airborne and spaceborne remote sensing systems have provided a range of tools for monitoring and managing human settlements. In particular the availability of very high spatial resolution satellite systems has dramatically increased access to high quality two-dimensional spatial information, while laser profilers and interferometric synthetic aperture radar have allowed acquisition of the third dimension. Over the past 100 years sensor systems have changed dramatically, from early airborne cameras that imaged only small parts of an urban area on a project return basis, to very high resolution spaceborne systems, covering a wide spectral range, with regular return periods down to a few weeks or days. This paper provides a brief history of urban remote sensing, followed by an examination of the properties of current systems and their acquired data, some processing methods and urban applications. It concludes with an overview of future developments.