A coastal area is exposed to a great number of threats such as smuggling, poaching, stealing fishing implements and some other crimes. These crimes are mostly committed after dark and in places where there are no lights. A thermal camera can detect heat energy and it has higher detection accuracy in complete darkness. Until recently, the cost of using the thermal camera has been prohibitive for usual practical surveillance. But new materials and other improvements make its price more reasonable and provide good tools for all-day surveillance. Using the thermal camera, we show some methods that provide the automatic video surveillance system with the ability to detect moving objects and determine the 3D positions and the sizes of these objects.