Research On Extraction Accuracy Of Laser Stripe Center In Three-Dimensional Scanning

One of the most popular methods to measure the surface profile of the object is to use the structured light 3D measurement technique.There are many advantages,such as non-contact,small volume,high precision,easy operation and real-time measuring.The key step is to extract the stripe center of structured light.In the actual measurement,a variety of factors will lead to the deviation of the laser stripe center.Therefore,it is necessary to analyze the deviation of the laser stripe center to provide the basis for the reliability and accuracy of the whole measurement results.In order to improve the accuracy of laser stripe center under complex conditions,a comprehensive study of the laser stripe on the complicated circumstances of the distribution has been done in this paper.We has established parameters analysis model of laser stripe under complex condition,and Half-edge Guassian fitting method has been proposed on the basis of the model,so the deviation of stripe center under complex conditions has been corrected.This paper mainly completed the following works:(1)The image preprocessing algorithm and laser stripe center extraction algorithm were studied.Firstly,according to the characteristics of the research object,the image clipping algorithm was proposed,and color images to grayscale images.Secondly,we analyzed the denoising results of the various image by filtering algorithm.We used median filtering which was most suitable for laser stripe images to denoise.The laser stripe images was threshold segmentation with Otsu algorithm.In addition,the typical laser stripe center extraction algorithm was studied.We analyzed the influence factors of the precision laser stripe extraction.Due to the image preprocessing,the influence of interference information on the accuracy of the laser strip center was reduced.(2)The parameter analysis model for the laser stripe was established.Firstly,we analyzed the main factors that affecting the gray distribution of laser stripe through the research.Secondly,theoretical derivation of these factors were established,the relationship between CMOS image sensor and the received light intensity,the relationship between the characteristics of reflectance and the gray distribution of laser stripe,the influence of laser incidence angle and laser divergence angle on the distribution of gray was analyzed.Finally,according to these relationships,composite function of parameter analysis model of laser stripe under complex condition was established.The model was through rigorous theoretical derivation analysis,which canaccurately describe the gray distribution of the laser stripe in the complex situation,and provide theoretical foundation and technical support to improve the accuracy of laser stripe under complex conditions.(3)Experimental design and result analysis.Firstly,the image of the laser stripe was obtained by experiments.Secondly,the accuracy of the model is verified by the experimental analysis of the laser stripe in the complex condition.The theoretical analysis of laser stripe center deviation and Half-edge Gaussian fitting method were compared,the error of 0.07 mm,but to achieve the desired results.Finally,we did the simulation test with the 3dMax software.It proved that the parameter analysis model and Half-edge Gaussian fitting method could be used to in the following experiments.