Study Of Several Problems On Active Video Surveillance

Along with the boost up of people's security consciousness, video surveillance has become very common. More and more cameras have been installed at airports, stores, parking plots and traffic crossroads etc. In order to improve the veracity and efficiency of surveillance, we should develop video surveillance in the direction of intelligentizing. The technique includes automatically carrying detection of moving objects, objects tracking, objects classifying and behavior understanding in video image sequence, etc. The purpose of the technique is to build a mapping relation between image and description of the image, thereby making computer be able to understand the content of video images. In this paper we introduce a removable camera into surveillance system consisting of static cameras. We discuss some problems related to the system, such as camera calibration, hand-eye relation calibration, moving objects detection and tracking, objects matching between these two cameras and the servo control of a dynamic camera etc.First of all, we discuss the calibration of cameras and eye-hand relation, in which the main work is as the following: (i) We present a method of solving inner parameters of cameras by using known kinematics information about the target objects in surroundings. The main idea of the method is: let the object shot make the translation movements in three directions which are not in the same plane, then by using the corresponding relationship of characteristic points on the two different images before and after the translation movement, we build up the equation and solve the inner parameters of the camera. Introducing the affixation variables instead of solving non linear equation, we can make use of several corresponding points on the object and obtain a group of linear equations. According to the restricting conditions of the variables, we solve the equation by means of Lagrange's Multiplier; (ii) We also present a method of detecting the translation position of the camera under its different inner parameters at different positions. The core of this method is putting forward a way to solve epipolar of image plane while focus distance varies. Besides, we make sure of the translation direction ofcamera coordinate system and give a method of examining camera translation position too. At the same time two simple methods of examining focus distance after adjusting camera focus distance are given. (iii) We come up with a new hand-eye calibration method, which is a kind of self-calibration method. It needs two characteristic points in the scene and controlling the plate do two translations and two rotations of camera plate to calculate rotation matrix and translation vector of hand-eye relation based on the correspondence between images after the camera movement. The difference from other methods is that as calculating translation vector of hand-eye relation, this one firstly makes the camera plate do pure rotating movement and then utilizes nominal rotation to make rotation change into the translation. At the same time we also give the calculating method for depth value of the points in the scene based on the active vision.The second, complex factors in the surrounding make the background model more and more complicated. In order to improve executing efficiency of examining moving objects, we present a method of constructing multi-pixel background model based on the image block. The method partitions the video image into blocks and constructs the background model according to the characteristics of the blocks. We give Gaussian mixture background model and LOTS background model based on the image block and carry out experiments to validate it.The last, in order to overcome the shortcomings of surveillance which consists of static cameras to track objects, hand-eye system should be introduced into video surveillance. We bring forward a kind of active video surveillance system. The system, composed of two cameras --- one static camera and the other removable camera, is a real time bi-camera tracking system. The aim of the system is to carry out the real time tracking down the unconventional object and to control the locomotion plate of the removable camera so as to make the object be tracked appear in the centre of the image in the dynamic camera. On the basis of calibration of cameras and hand-eye relation of the system, we give approximate homography relation between two cameras'image planes by making use of the characteristics of the surroundings watched. From this we can establish a method to correspond the objects on the two image plates between two cameras. In the system, 2D motion model is established on the image plane of the static camera to predictthe position of the object by Kalman filter. Then by using homography relation, the prediction of the object position can be obtained on the image plane of the dynamic camera. Finally, after calculating the rotation angle of the dynamic camera plate, we can implement the servo control of the dynamic camera. We also discuss the technical problems of the error compensations of the system.