Fast-speed,High-accuracy 3D Measurement Method Research Based On The Fringe Projection

The purpose of three-dimensional(3D)measurement is to obtain the 3D information of the object.Among all 3D measurement methods,the 3D measurement technology based on fringe projection is a modern measurement technique which integrates the optical theory,computer vision,image processing,digital signal processing and other disciplines.It is widely used in industry production control,reverse engineering,biomedical,heritage preservation,and other fields owing to its advantages of high precision,large data volume,fast detection speed,wide application range,and non-contact.The technique has high application value and very considerable development prospects.With the rapid development of 3D optical measurement technology and manufacturing industry,how to achieve fast-speed and high precision 3D shape measurement becomes particularly important.Based on the actual demand,this paper studies the problems of fast-speed and high precision 3D shape measurement of fringe projection,the main contents are as follows:1.In this paper,a segmented phase-coding fringe based on geometric constraint of the DFP system is used to achieve fast-speed,high-accuracy 3-D shape of the complex surface.However,for the traditional combination of phase coding and sinusoidal fringe,the sinusoidal fringe cycle is equal to the phase coding fringe cycle.As the number of phase coding fringe cycles increase,the fringe order becomes difficult to judge,ultimately leading to phase unwrapping errors.To resolve this issue,this paper using segmented phase-coding fringe based on geometric constraint of the DFP system to obtain the segmented fringe order,then geometric constraint of the DFP system are used to correct the fringe order.This method alleviated the difficulty in judging the fringe order and,consequently,improved measurement accuracy.Experiment results validated the efficiency and accuracy of this novel method.2.A fast 3-D shape measurement method based on sinusoidal and triangular fringe projection is proposed to achieve fast-speed 3-D shape measurement of the object.Existing methods to measure 3-D shape of complex object involve processing more than six captured images to obtain the absolute phase,which limit the measurement speed.This paper presents two sinusoidal fringes and two triangular wave fringes used to measure 3-D shape of complex object.The two-step phase-shifting sinusoidal fringes and two-step phase-shifting triangular wave fringes are calculated to obtain the wrapped phase,and then the two-step phase-shifting triangular wave fringes are used to determine the fringe order.Due to decrease the number of projection fringes,the speed of measurement increases.In order to obtain the fringe order,the triangular wave fringe intensity ratio is calculated.Compared with the calculation of phase,the time for processing data is reduced,so the measurement speed is further improved.Experimental results have demonstrated that the proposed method can improve the measurement speed,and the measurement accuracy is also improved.