| Three-dimensional measurement technology is a technology to obtain the threedimensional topography data of the object surface.It mainly uses measuring instruments,sensing equipment and measuring means to obtain the three-dimensional coordinate points of the measured object.Structured light 3D measurement technology is an important method in3 D measurement technology.By actively projecting encoded structured light patterns onto an object,the modulated image information of the object being measured is obtained,and the three-dimensional topography data of the object is obtained using the triangulation principle.In the structured light three-dimensional measurement technology,the grating fringe projection method is widely used in many industrial and scientific research fields such as industrial measurement,medical treatment,cultural heritage protection,virtual reality and so on because of its advantages of high accuracy,low cost,easy implementation and good application prospects.In this paper,the research of structured light 3D measurement technology based on binary encoded grating patterns are carried out.In view of the key problems such as the limitation of measuring the depth of field and the reduction of image contrast existing in the binary fringe defocusing technology in the current practical application scene,a structured light measurement system suitable for the projector to focus the scene and project the binary fringe patterns for measurement is designed.The experimental results show that the proposed method allows the projector to complete the measurement under the condition of focusing in the whole measurement process,while reducing the nonlinearity and the influence on the contrast of sinusoidal fringe and the measured depth of field.The root mean square error obtained in the standard sphere measurement experiment in this paper is 0.0425 mm.The main research contents of this paper are as follows:(1)for standard multi-step sinusoidal phase shifted fringes,the binary patterns are encoded according to the law of the intensity change of the sinusoidal fringe within a single cycle.During the encoding process,the number of patterns involved in the operation and the algorithm are designed synchronously,so that the encoded binary fringe patterns can be processed by the designed algorithm to generate sinusoidal phase-shift fringe patterns that can be used for actual measurement,thus allowing the projector to complete the measurement under the condition of full focus,and solving the problem that the binary fringe defocus technology limits the measurement depth of field.(2)By using the subtraction operation of binary images and the black image,the error caused by different intensity values in the inverse trigonometric function operation is ingeniously eliminated,and the calculation result is as linear as possible.(3)Multiplexing the binary encoded images that generate sinusoidal stripes,constructing the planar images required in the phase shifting method,reducing the projected planar patterns,and performing actual measurements with as few patterns as possible,making the final measurement results meet certain speed requirements. |
