Deformation and displacement measurement method in model test based on image processing

Abstract

The invention provides a deformation and displacement measurement method in a model test based on image processing. The method comprises the following steps of: dotting and marking an area, needing deformation and displacement measurement, of a measured model in a model test; meanwhile, arranging a calibration plate in a test scene; shooting pictures, and carrying out distortion correction and perspective transformation on the shot pictures successively to obtain perspective-transformed images; carrying out feature point detection on the perspective-transformed images; performing feature pointmatching on the same mark point by using the perspective-transformed images acquired at two different time points to obtain a plurality of feature point pairs; calculating the displacement of the mark point in the period of time; and calculating a dynamic displacement field or a deformation field of the measured plane area through the displacement combination of all mark points. The problems thatin the prior art, the surface of a measured model needs to have large roughness, irreversible treatment such as speckle spraying needs to be conducted on the surface, a fixed datum point needs to beset, the measurement principle is complex, and measurement equipment and an operation system are expensive are solved.

Description

technical field [0001] The invention specifically relates to a deformation and displacement measurement method in a model test based on image processing. Background technique [0002] In the model test, non-contact measurement is often used to obtain the deformation and displacement in the model test. This method is used in the comparison file 1 (Liu Haoyang. Research on the displacement deformation measurement method based on digital image processing [D]. Jilin Agricultural University.) , to perform image processing on the natural speckle, artificial speckle or laser speckle of the model under test. [0003] But among them, digital image correlation technology (DIC) needs to make speckles that are difficult to remove on the surface of the measurement area, digital speckle image technology (DSP) and digital speckle interferometry technology (ESPI) are based on the diffuse reflection of rough surfaces, requiring The surface of the measurement area has sufficient roughness. I...

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Problems solved by technology

[0005] However, the image processing in this document needs to set control points, that is, a fixed reference point must be set, and the method of using the quadrilateral unit isoparametric transformation method to realize image calibration is relatively complicated, and it is difficult to popularize and improve the efficiency in actual use

In comparison file 2, after picking up the punctuation parameters, the coordinates of the center of mass of the punctuation are identified, and the coordinates of the center of mass of the punctuation are used for displacement calculation. The punctuation recognition and calculation results are not accurate enough.

The punctuation recognition method in the comparison file 2 has rigid requirements on the size and shape of the punctuation points, which cannot well meet the needs of on-site use, and the detection area is the entire image, and there is a problem of punctuation recognition errors, so the program design in the comparison file 2 Only semi-automatic and manual recognition methods are available to correct the problem of wrongly recognized punctuation, which increases the workflow and workload, and reduces the effectiveness and accuracy of recognition

[0006] Therefore, it is necessary to provide a method for measuring deformation and displacement in model tests based on image processing to solve the problems in the prior art that the surface of the model to be tested must have a large roughness, and the surface must be treated with irreversible treatments such as jet speckle. Fixed reference point, complex measurement principle and expensive measurement equipment and operating system

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