Research And Application Of Digital Close-range Photogrammetry Technology In Steel Truss Joint Test

In the test of steel truss joints,displacement meters are used to measure the displacement of the test body.The displacement measuring of steel truss joints generally includes the displacement of each member of the joint,the rotation angle of the member and the overall displacement of the joint.The displacement meter has a complicated arrangement and long preparation time.The article uses digital close-range photogrammetry technology to conduct full-field deformation measurement of steel truss joints for static load testing.Digital close-range photogrammetry technology is non-contact measurement,data collection is convenient,and operation is simple.The article analyzes the basic theory of digital close-range photogrammetry,studies various methods of digital camera calibration,and finally selects the calibration method of the indoor calibration board for the digital camera used in the experiment to perform the internal orientation elements and the optical distortion correction of the lens.Through research,it is found that the digital camera-based digital close-range photogrammetry requires artificial markings.This paper combines the actual shooting environment,the characteristics of the shooting steel truss joints and the test shooting requirements,and selects suitable artificial marks for placement to ensure or improve the shooting accuracy.Identify target features.According to the deformation measurement requirements of the steel truss node and the shooting environment,a shooting plan was designed and the digital images of the steel truss joints were acquired according to the shooting plan.The image is pre-processed after the image is acquired,and the image is denoised to enhance the contrast of the image to make the image feature more obvious.The noise-reduced images were imported into the measurement software PhotoModeler Scanner to process the images.The displacements and rotation angles of the steel truss joint members were obtained,and the deformation of the steel truss joints was obtained.By comparing with the measurement results of the displacement meter and the finite element analysis results,this test method has certain accuracy,which shows that the digital close-range photogrammetry technology has good applicability in the test of steel truss joints,and the analysis method can be very good through research and analysis.Meet the accuracy requirements of the experiment.It provides a new method and idea for displacement measurement of steel truss joint test.