Research On Key Techniques And Application For Active Stereo Vision

Sharing mechanisms with biological vision systems, the active stereovision system is the primary way to obtain 3D information in machine vision field, whose applications span navigation of mobile robots, autonomous vehicles, surveillance, industrial process and so on.Firstly, This paper presents the design and development of active stereovision platforms and their integration into real-time closed loop active vision systems. The active stereovision system, built from off-the parts, allows accomplishing visual tasks independently like pan, tilt, vergence and camera parameters adjustment. Important parameters for the stereovision system such as the selection of motor resolution and size of baseline have been taken enough consideration. The strategies adopted for the design of the system, including mechanical design of platform, closed loop servo controller for motor of pan, tilt and vergence, camera parameters adjustment controller, and system integration, proved to be very successful.As for stereo matching, feature based matching method is preferred than intensity-based. Line segments, corners and polygonal regions are selected as features to be matched. Firstly, an improved Canny edge detection algorithm is represented to obtain thin and robust edges. Secondly, based on detected edge gradient of image, an iterative chain code tracing method with parallel hierarchy is introduced for line segment detection. Finally, combined with definition and geometrical structure, corners and convex polygonal regions are detected based on line segments. The use of these high level features, although helping to diminish matching ambiguities, does not completely resolve when the scene contains similar structures. The epipolar constrain, unique and continuity constrain, order constrain, spatial constrain and so on are employed for stronger support for correct feature matching pairs and, as a result, incorrect matching pairs can be largely eliminated.Camera calibration is an important prerequisite for retrieving 3D information of scene. Considered with peculiar configuration of stereo camera, some reasonable assumptions are introduced to obtain simplified stereo camera model. Based on the simplified form, a self-calibration method for moving stereo camera is represented in this paper, which calculates camera parameters through a successive motion sequence while camera focus remains invariable during the motion. The principle of retrieving3D information based on corresponding feature points and line segments is also discussed later.Finally, new generation autonomous vehicle based on stereovision navigation is highlighted as a future application.