Urban Monitoring by 4D Change Detection Using Multi-temporal SAR Images

The continuous rise in population and economic growth has led to frequent urban changes such as construction. Monitoring such changes is important for city management, urban planning, updating of cadastral maps, etc. In contrast to conventional field surveys, which are usually expensive and slow, remote sensing techniques are fast and cost-effective alternatives. Spaceborne synthetic aperture radar (SAR) provides radar images captured rapidly over vast areas at fine spatiotemporal resolution. In addition, the active microwave sensors are capable of day-and-night vision and independent of weather conditions. The advantages mentioned above make SAR suitable for monitoring tasks. Change detection approaches based on multi-temporal SAR images are widely used for urban monitoring. We developed a novel 4D change detection technique, which is capable of detecting spatial changes (3D) and occurrence times (1D). In this study, we apply our technique to a built-up area in the centre of Berlin, Germany. As a result, the disappearing and emerging structures along with their occurrence times are successfully detected. We have demonstrated that these spatiotemporal results are able to provide detailed and comprehensive information for urban monitoring.