Abstract: A method of monitoring monitored locations by means of a monitoring system. The monitoring system comprises a plurality of monitoring modules 1, each of which has a light-sensitive sensor for monitoring the monitored locations. The monitoring system further comprises a remote monitoring station 3 with an operator. The method comprises the steps of recording by each of the monitoring modules 1 an image of the monitored location associated with the monitoring module 1, extracting in each of the monitoring modules an area in the recorded image that differs from a reference image, and extracting in each of the monitoring modules an object from the area.