Many countries around the world have implemented or are in the process of implementing tighter security measures in public and private places. Such measures are becoming widespread and are applied not only at government, military, and corporate facilities, but also in civilian infrastructures. Modern surveillance system consist of different modules. A sensor layer usually consists of a network of cameras, audio arrays, physical perimeter sensors, and other types of information feeders. A surveillance layer represents the core of the intelligent system. Its role is to process all the data generated by the sensor layer.This module includes several components. A feature extraction step is responsible for reducing the enormous amount of data that the network generates. Time properties are commonly derived by keeping track of any action within the monitored environment. The module in charge of the event analysis is at the highest processing level of modern monitoring systems. Human-computer interaction is fundamental to providing relevant, timely information.