The Research Of Parameters Acquisition Method Of Bridge Cable Tower Based On Image Analysis

The large bridge has become a kind of necessary public infrastructure for themodern transportation and our China has been one of the counties which have the mostbridges in the world. With the bridge construction technology maturing and more bridgecollapse accidents occurring, people’s focus are turning to the field of bridge healthmonitoring.The main methods to achieve the bridge health monitoring are sensing,photovoltaic and information technology and expert analysis and comprehensive whichare used to monitor the information of bridge crack, displacement, deformation anddeflection. The main content of this article is to apply the digital image processingtechnology in the field of bridge health monitoring, combining the knowledge of cameraacquisition and photovoltaic technology to achieve the accurate and long-termmonitoring of parameters of Bridge pylon’s crack, displacement and deformation.The theoretical basis of this paper are the common algorithms of the digitalimages processing, the generalized structure, the extended morphological filtering andthe laser measurement. This paper are divided into three parts: the first part is therecognition system of Bridge pylon’s crack based on the image analysis; the second partis the measurement system of Bridge pylon’s displacement based on photovoltaictechnology and image processing; the last part is the discussion of the measurementmethods based on the three basis points and second basis points differentialdisplacement.The recognition system of the Bridge Cable Tower’s crack based on the imageanalysis: Propose the program for the long-term monitoring of the Bridge Cable Tower’scrack through the video equipment and the remote computer; Elaborate the crackautomatic identification based on the generalized structure and extended morphologicalfiltering algorithm; Include the image preprocessing, the crack identification, the imagemosaic of video sequences and the crack geometry parameter calculation and so on.The measurement system of Bridge Cable Tower’s displacement based onphotovoltaic technology and image processing: The function of this system is to monitorthe Bridge Cable Tower’s displacement and deformation all the time and generate thetrend graphic in order to get the exact health information of the monitored object. The main methods are to exploit the theory of the laser alignment spread, to use the CCDvideo capture device and combine the knowledge of digital image processing to workout the displacement and deformation of the bridge, additionally to draw thedisplacement map.This article proposes the fast calibration algorithm(FCA) based on the planarnetwork depending on the application and accuracy requirement. By building therelationship between the known practical magnitude of the network and thecorresponding pixel in FCA, I can get the ratio between the two values that just is thedemarcating result. During this process, the key is the identifying process of thegrid-dings and in this paper, I can identify the grid images accurately using theimproved HMT algorithm.In this paper, through deciding the moving distance of the laser spot firstly, I canidentify the displacement and deformation of the bridge pylon’s test point. Thus the keytask of this paper is the distance calculating of the moving laser spot. Using the methodof the digital image processing, I can get the accurate center coordinates of the laserspot besides it demands strong anti-jamming capability.Taking into account of the error caused by using the common total station andrangefinder measurement, I propose the measurement methods based on the three basispoints and second basis points differential displacement. The starting point of thismethod is the differential technology which determines the measurement error betweenthe practical and measuring coordinates of the base point’s position, then correct themeasurement result, so as to get high accuracy measurement program.