Accuracy Analysis And Application Of Single Camera Measuring System

Single camera close-range photogrammetry is a branch of photogrammetry.It uses a single digital camera to carry the multi-directional shooting of the objects with the mark points,get the photos of these points.The three-dimensional coordinates of the mark points are calculated by the digital image processing algorithm and the photogrammetric algorithm to achieve the purpose of measurement.In the measurement of traditional civil engineering experiments,displacement meters and other measuring equipment are often subject to the number of measuring points,measurement direction and installation conditions and other restrictions.However,the single-camera close-range photogrammetry system can measure a large number of measuring points at the same time,and has the advantages of non-contact,flexible measurement and low measurement cost.In this paper,the CMM 2015 single-camera photogrammetry system is studied,and the measurement accuracy is evaluated from the aspects of center recognition,camera selection and precision of reference ruler.Finally,it is used in the measurement of civil engineering structure,which can meet the displacement measurement requirements of civil engineering experiment.The research contents and research results of the thesis mainly include the following aspects:Firstly,in this paper,for CMM 2015 single camera close range photogrammetry system as the research object,design the experiments to study the accuracy of center positioning.Compared with the Gaussian curve fitting method and the gray point square moment method,it is found that the Gaussian curve fitting method is less affected by the noise than the gray square moment method,the positioning stability is higher,the maximum can reach 0.02pixel,and the gray scale Square moment method only 0.1 pixel.And then studied the shooting angle on the center of the positioning stability of the impact and found that in the case of small angle shooting,the positioning of the center of the basic stability is not affected.And then from different parameters to consider,design experiments to study the impact of displacement measurement accuracy.First compared to the IDS industrial camera and the Nikon SLR camera,it was found that the accuracy of the displacement measurement with the IDS camera was 0.03 mm and the relative accuracy was 0.017%when the camera’s resolution was the same,and the Nikon SLR camera had the same accuracy 0.06mm,the relative accuracy of only 0.034%.Then,designing an experimental study of the effect of the reference foot on the displacement measurement accuracy.Using the displacement table with a precision of 0.01 mm as the reference ruler,when the measurement range of 0.5 meters,the displacement measurement accuracy of CMM₂015 measurement system can reach 20～30μm,the relative accuracy of 0.04mm/m.Finally,used this method to correct the carbon fiber tube reference rulerAt the end of this article,CMM 2015 single-camera close-range photogrammetry system was used to measure the wood structure trusses and the mixed reinforced concrete beams in the civil structure.Use this system to measure the displacement of an object under load.The displacement of the measured points coincides with the theoretical data,indicating that the measurement system can be applied effectively in the measurement of large-scale civil structure.