A Novel Activity Detector Applied to Sentinel-1 for Surveillance

Change detection is the challenging process of identifying meaningful changes on an image sequence. In this work, we propose a new change detector for SAR images. We show that by controlling the a priori number of false alarms, one can detect events and filter out very small detections without first applying an anti-speckle filter. A detection is made in the absolute log-ratio image when enough pixels in a neighborhood exceed a statistically pre-determined threshold. This flexible approach allows several neighborhood shapes and sizes to be tested while controlling the number of false alarms. A global bound on the desired expected number of false alarms automatically determines the detection thresholds for each tested configuration.