Three-dimensional Measurement Technology Based On Structured Light

In all fields of life,there are various means of obtaining 3D information,and there are also different standards for the accuracy of 3D information.Traditional contact measurement methods using rulers and other equipment have been unable to meet the actual needs,such as collecting three-dimensional data of objects in extreme natural environments,measuring substances of brittle materials,and even the shape of the detected objects is irregular.Among the new measurement technologies,structured light 3D measurement technology has attracted much attention due to its advantages of non-contact and high accuracy.Based on the research progress at home and abroad,the optical binocular measurement system is more widely used than the monocular one.Structured light binocular measurement has the advantages of high measurement accuracy and removal of object occlusion.However,the binocular system is not perfect in terms of hardware complexity.The accurate measurement accuracy is obtained with the cost of complex system calibration,the large number of image acquisitions,and multi-view feature matching.Although the monocular measurement corresponding to the binocular structured light measurement is simple in equipment and easy to operate,it has always been limited by the measurement accuracy so that it is difficult to be widely used.(1)Aiming at the accuracy of the structured light monocular measurement system,this paper proposes a Siamese plus STN network which is called SSTN network.Symmetrical viewing angle transformation is achieved through SSTN,and a small angle rotation is performed in the horizontal direction,thereby expanding the amount of data obtained from the image.Because the SSTN can directly complete the image matching,view of the operation process,this method does not make the monocular measurement cumbersome.In this paper,a new algorithm is used to achieve the effect of a quasi-binocular system with a monocular device without changing the complexity of the device,thereby improving the measurement accuracy.From the experimental data,the structured light measurement using SSTN improves the measurement accuracy by 30% and suppresses the error to less than 0.1 mm.(2)When the structured light system is used to measure the surface of the object with high reflectivity,the structured light image collected by the camera will have the problem of partial brightness saturation,which will cause the signal to be distorted or lost,and thus cannot achieve accurate three-dimensional topography measurement.Aiming at the above problems,in order to complete the three-dimensional topography measurement of the strongly reflective surface,this paper uses optical knowledge to analyze the optical path of the strongly reflective surface in detail,and proposes a reflection compensation phase shift method.RCPSM divides the strongly reflected light into three parts,and inserts a compensation value in the phase shift method according to the characteristics of different parts of the optical path.The method improves the anti-interference ability of the encoded image,and can well solve the problem of missing image information caused by the complex optical path on the surface of the reflective object.From the experimental results,the method proposed in this paper can effectively deal with the image saturation caused by the reflection on the surface of the object with high reflectivity and eventually achieve good visual effects.In short,this paper proposes SSTN and RCPSM to solve the two shortcomings of monocular structured light 3D topography measurement in practical applications,called low measurement accuracy and poor anti-reflection ability.There are four experiments carried out in this paper.The measurement results before and after the improvement were compared in pairs,and the advantages of the method in this paper and the future improvement direction were analyzed.The final measurement results show that the method proposed in this paper indeed improves the measurement accuracy of monocular structured light,and suppresses the influence of reflection on the measurement effect.