Vision Based Depth Measurement And 3-D Topography Reconstruction

The tread damage of wheel seriously affects the running safety of trains.It is an important content of the train wheel health monitoring that can obtain the damage information of treads quickly,accurately and in real time,get the damage "shape" and "appearance" at the same time without affecting the operation of trains.In this paper,the methods of depth measurement and three-dimensional topography reconstruction on the surface are studied,and triangulation and FTP are used to detect the defects of the motive tread surface,achieve the online detection and 3-D topography reconstruction.And designed a three-dimensional visual measurement management software system combined MFC and.NET technology.The main contents are as follows: 1.Through the analysis of triangulation measurement principle,imaging principle and system optical structure,the formula for obtaining the depth information and surface information is obtained.The structure of the detection system and the placement of the main device.Carry on some experience to the tested wheel,and adopt appropriate image processing algorithm to achieve the depth measurement and three-dimensional reconstruction of the wheel tread.The analysis of the detection accuracy verify the feasibility of this method.2.The depth measurement and 3D reconstruction of wheel tread surface are realized by using the principle of divergent grating projection,in which FTP is used to extract the phase of fringe pattern.The phase relationship between the phase and the height is obtained,and the method of obtaining the phase of each point on the measured object is obtained by system structure analysis.The three-dimensional topography reconstruction is carried out on the tested wheel,and the test results are analyzed,confirmed the feasibility of this method.3.A visual measurement system with functions of data acquisition,data processing and data management is developed.The four subsystems of camera calibration,image acquisition,image processing and data management are designed and implemented,which can meet the need for most 3D visual measurement applications.The work and research results in this paper have important reference significance for the research of dynamic wheel's on-line defect detection and 3D topography reconstruction.