Research On 3D Visual Measurement Method Based On Structured Light

The three-dimensional visual measurement method based on structured light is a non-contact three-dimensional measurement method.The basic measurement principle is to use a computer to generate a certain structural light pattern,which is projected onto the surface of the measured object by a projector.The object will generate a phase modulation on the projected structured light pattern and behave as a structural light pattern with a certain degree of deformation.In the monocular system,the phase of the parcel is demodulated using the phase shift method and the Fourier transform method,and phase unwrapping is performed.The three-dimensional coordinates of the object are obtained according to the phase-height relation in the system model.In the binocular system,the gray pattern is used to encode the structural light pattern,and the stereo matching of the binocular system is completed,and then the three-dimensional coordinates of the object are solved according to the triangulation method.Based on the structural light,this paper mainly studies the 3D reconstruction method related to the monocular system and the binocular system,and applies the reconstruction method to the measurement of actual objects.The main contents are as follows:(1)Studied the method of 3D reconstruction in monocular system and pointed out the key steps of 3D measurement of monocular system:system calibration and phase unwrapping.In the camera-projector system,a rigorous mathematical model is established and related parameters are solved,and the restoration of the three-dimensional appearance of the monocular system is achieved with high accuracy.In terms of phase unwrapping,an improved algorithm can accurately solve the phase principal value and perform phase unwrapping,which improves the speed and accuracy of the three-dimensional shape restoration.(2)The method of three-dimensional reconstruction in binocular system is studied.For the problem that the traditional stereo matching method does not have many matching points,this paper adopts the Gray code encoding structured light pattern method,which makes each pixel in the structured light pattern projected out.Each point has a unique code value corresponding to it,which significantly improves the accuracy of binocular stereo matching and the dot density.In terms of three-dimensional calculations,theoretical and practical errors are handled rationally based on the solution of a vertical line,and good results are obtained.(3)The calibration of the camera-projector system in the monocular system and the calibration of the camera in the binocular system determine the accuracy of the three-dimensional measurement.This article uses Bouguet's camera calibration toolkit to achieve a higher accuracy of the camera calibration.After researching,it is pointed out that the projector can be regarded as a reversed camera,and the plane-based calibration method can achieve higher accuracy of the projector calibration.(4)For the problem of high-precision measurement of static targets,a three-dimensional topography measurement system with binocular structured light was constructed.Using python-opencv to encode,using the Gray code encoding method to reconstruct static target projection 42 coding patterns,a complete set of binocular coding structure light measurement system was established,the static object measurement accuracy of 0.2mm,and complete the software achieve.