A Three-dimensional Measurement Method Based On Multiple Reflection Imaging

Since the 1970 s,optical 3D measurement technology has been widely used in many fields of industrial production due to its high accuracy and high efficiency.With the development of laser technology,digital image processing technology and computer technology,optical non-contact surface 3D measurement has become more and more important in the field of 3D measurement.In industrial production,there are many reflective surfaces similar to metal surfaces.The reflected light shining on such reflective surfaces changes drastically with angle.The reflected light captured at different angles will be significantly different.In some locations with strong reflection,this will even make it unusable for measurement.In addition,when the same parameter is used to match or process the image,if the material with a large difference in reflectance and reflection performance occurs at the same time,the accuracy of the measurement result will be poor.Therefore,how to measure the three-dimensional topography of high-reflection surfaces has become an important issue.Our research group proposes a three-dimensional structured light measurement and instrument calibration method based on the formation of multiple reflection imaging.This method solves the spatial coordinates of the structured light image points by establishing the relationship between the image coordinates and the spatial coordinates of the corresponding points of the multiple reflection image,and is used to overcome the large brightness contrast and high refletion problems to a certain extent.The main research contents of this article are as follows:1.The three-dimensional measurement of structured light is the mainstream method used in the current optical three-dimensional measurement,This article gives a general introduction to the basic knowledge of the cameras involved in the current 3D measurement of structured light,and the main methods and principles of 3D measurement of structured light;2.A key step involved in the structured light measurement process is centerline extraction.This article introduces several widely used methods for extracting the centerline at this stage,and selects the most applicable and efficient method for the experiment according to the objects and conditions in the research process of this article;3.Based on a structured light three-dimensional reconstruction device and method based on a 50-50 beamsplitter and a reflector to form multiple reflection images,the calibration and calculation methods are improved,and quantitative measurements are made on different materials,the measurement accuracy and range of this method were initially determined.Experiment shows that this method overcomes the problems of large brightness contrast and high contrast encountered when using structured light to measure high-reflection surfaces to a certain extent,at the same time,it can meet the requirements of engineering simplicity and low cost.Its measurement accuracy is within 0.1mm on the experimental platform of this paper.