Structured Light Measurement Technology Research Based On Sinusoidal Fringe

Measurement is an important method for humanbeings to understand the world and is thebasis of science development. With the development of manufacturing industries，the largescale， high aceuraey，even all attitude and dynamical measurement are required.Thetraditional three-dimensional measurement technology(CMM) can not meet theserequirements.In this context the vision measurement techLnology emerges and is becomingmore important.Based on the rigorous theory and modern software and hardware facilities，vision measurement system has been closely combined with computer.The visionmeasurement technology as a non-contact， high accuracy，rapid measurement method hasbeen applied widely.Structured light vision measurement is a branch of computer vision; it becomes theresearch hot spot in recent years.But the structured light vision technology still sufferedlimited during the practical application, for example,a great number of structured lighttechnology cannot be applied to dynamic scene,and real-time performance is not satisfactory.Structured light technique utilize a projector instead of one camera in binocular stereovision;This paper studies the spatial encoding method based on sinusoidal gratings,whichsolves the problem of stereo matching by absolute phase uniqueness of sinusoidalgratings.and finally achieve three-dimensional measurement of objects.This paper study the encoding and decoding of the sinusoidal grating structure.thecodification of structured light pattern and the decoding of symbol image affectsresolution,robustness and precision and even the detection success ration,The main work is asfollows:firstly,study the generation method of sinusoidal gratings,Sinusoidal grating is the basisof the coding method.there are two methods to generate the sinusoidal grating.One is to use amechanical grating film,The advantage of this method is the high accuracy,However, itsflexibility is poor.Another method is to project sinusoidal fringe by projector.This method islow cost and high flexibility,and can be programmed to generate a sinusoidalwaveform.however,there will be some loss of accuracy after discretization of sinusoidalwaveform.secondly,study the encoding and decoding method of the sinusoidal grating.Throughprojecting six sinusoidal grating with different initial phase encodes observation point on the surface of the measured object.and then,Camera captures the encoded image anddecodes.finally,achieve stereo matching of binocular measurement system by absolute phaseuniqueness of sinusoidal gratings.In the process of decoding, get a pair of two-dimensionalrelative phase map.however its value between [-π，π]，So this paper studies and analyzes thevarious phase unwrapping methods.Finally, using the branch-cut method combined with theflood fill method for phase unwrapping the, obtained very good expansion effect.thirdly,according to the decoding result together with calibration results obtain thecoordinates of the point on the surface of the measured object and3D reconstruction isfulfilled.According to the method proposed in this paper, with a cylindrical as target, do athree-dimensional reconstruction of the experiment,And get the3D point cloud images and3-D images of the cylinder,Using the3-D images of a plane graph obtained cylinder measureddiameter, analysis of the experimental results with the actual diameter value.Experimentalresults verify the validity of the proposed method.Finally,analyzed the sources of error in the system,and gave a brief introduction ofmethods in this system to improve measurement accuracy.Structured light3D measurement systemmust exist such as measurement error, in order to better improve the measurement system and maximize thereduction of the measurement error, analysis the error in this paper. Firstly, this chapter introduces the erroranalysis in the optical3D measurement and compensation of research, and then systems analysis the errorsources and some improve method in this chapter specific measurement system.