| Traditional method to obtain the parameters of structure is carried out by using sensors.However,the sensors cannot be used where the style of the structure is complex.Much more money will be costed for some tall buildings which need many wires.To solve these problems,the method of image matching to obtain the displacement and strain of structure is given.The target matching algorithm based on PSNR(Peak Signal to Noise Ratio)criterion calculates the mean square error of the pixel values between the two pictures,which can give conclusion that whether the two pictures have similarity.The bigger the PSNR value is,the more similarities the two pictures have,vice versa.The PSNR criterion includes the image preprocessing,image segmentation,image matching and camera calibration.Image preprocessing mainly includes image gray-scale and image denoising.The rough location is performed by the edge detection operator and the sub-pixel location method.The PSNR-based matching algorithm is used to match the target to obtain the position of the object in the moving image,which is used to obtain the displacement of the pixel.Finally,the pixel displacement is converted into the actual displacement by camera calibration.Displacement acquisition and parametric analysis based on image matching,which are used to obtain the displacements of the single point displacement mode and the multi-point displacement mode respectively.The displacements calculated in different displacement modes are compared with the theoretical values.On the other hand,this paper analyzes the factors that influence the displacement calculation based on the difference of rough location operator and different matching regions.The detection results are compared by the detection image quality and the relative error,which can provide data support to improve the accuracy of the algorithm.Strain acquisition based on image matching,which gives the calculation of the strain of the steel joint using the laboratory joint test.The strain of the steel surface is studied and the factors that influence the strain calculation are studied.The strain value calculated by the image matching and the strain value monitored by the sensor are compared and analyzed. |
