Monitoring of Construction Activity by Change Detection on SAR Time Series Using Coherent Scatterers

In this article, a novel synthetic aperture radar (SAR) change detection method for the monitoring of man-made objects (MMOs) is presented. Rather than looking for changes in SAR amplitude or the loss of coherence, changes are detected by the appearance and disappearance of the strong point scatterers present in MMOs and often denoted as coherent scatterers (CSs). This enables the detection of changes involving MMOs while ignoring changes to natural targets such as vegetation. These CSs are detected in each image and compared coherently across an image pair or a time series. When using a time series, the proposed method can categorize the changes according to their temporal behavior. An object-based change analysis step for identifying changes significantly larger than individual CSs is also introduced. The proposed approach is applied for the monitoring of construction activity using a time series of 49 TerraSAR-X images of the city of Munich.