SAR applications in human settlement detection, population estimation and urban land use pattern analysis: a status report

Over 70 percent of the population of the world's developed countries live in urbanized areas. In developing countries migration to urban areas is continuing at an increasing rate. Detection and analysis of settlement patterns, estimating population, and monitoring population migration in a timely manner are requisite to accurately assess the impact of human activities on the environment. Monitoring urban land use change patterns is among the most critical information needs for future economic development planning, natural resource allocation, and environmental and ecosystem management. Previous research has demonstrated the potential of imaging radar systems in analyzing urban, population, and settlement phenomena. However, the variability and complexity within and between urban land use morphologies present a convoluted environment for analysis. Studies of vegetation, soils, geology, hydrology, and ice and snow have all received more attention and been the subject of considerably more widespread and in-depth radar research. Nevertheless, imaging radars offer some distinct advantages and opportunities for urban-based research. With the arrival of operational space imaging SAR systems, a review of the current status of applications of radar remote sensing in urban studies should be useful for focusing the authors' attention on this important area of radar research and identification of specific problems for in-depth analysis. This paper traces the history of imaging radar research for urban, settlement, and population analysis. It presents a status report on the applications of SAR in settlement detection, population estimation, assessment of the impact of human activities on the physical environment, mapping and analyzing urban land use patterns, and interpretation of socioeconomic characteristics. The demonstrated capabilities and limitations of past and current imaging radar systems with reference to these applications are described. Potential avenues of future research are addressed.