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Abstract By analyzing the present image processing techniques applied to deformation monitoring，the advanced target method—subpixel centre detection algorithm is proposed based on the traditional gray weighted detection algorithm and detection algorithm of circle edge. The accuracy test is designed to research its advantages comparing with the traditional algorithms through 4 aspects：target size，camera distance，light intensity，state of target motion. In return，we can get the theoretic accuracy of the method. Based on the features of mark displacement，the new technique of deformation monitoring is put forward. And the applicability test is carried out considering 3 aspects：camera distance，light intensity，state of mark motion. The results indicate that：(1) The subpixel centre detection algorithm with targets can get the higher identification precision with less than 1 mm in shooting distance of 50 m(circle of diameter 15 cm). (2) It is feasible with its sensitivity to catch the mark displacement. When the shooting distance is less than 40 m，the identification error could be controlled to 1.0 mm. And when the shooting distance is less than 25 m，the identification error could be strictly controlled to 0.5 mm. In addition，according to Shicheng—Ji′an highway project in Jiangxi province，the new technique is applied to detect the slope deformation，which testifies its high engineering applicability. The theoretical study and tests confirm the higher accuracy rate，technical feasibility，engineering applicability，and feedback ability in time of the new technique based on the advanced algorithm.
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Received: 13 May 2011
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2011, Vol. 30 
