Research On Visual Field Measurement System And Method For Protective Eyeglasses Based On Computer Vision

Protective eyeglasses are the necessary equipment to protect the safety of the eyes.It is very important for wearers to judge and measure the visual field of protective eyeglasses.At present,there are few studies on the visual field measurement of protective eyeglasses at home and abroad,and the artificial measurement system and method are still used in the actual detection.The measurement process is cumbersome and the degree of manual participation is too high,which leads to poor repeatability and accuracy of the measurement results.With the development of metrology,the detection accuracy and requirement of measurement system are getting higher and higher.It is particularly important to study the intelligent protective eyeglasses field measurement system and method.In view of the singularity and inefficiency of visual field measurement for protective eyeglasses at present,a visual field measurement system for protective eyeglasses based on computer vision is proposed by this paper.The measurement system is mainly composed of standard head model,fiber light source,light guide screen,industrial camera,computer and so on.It takes human visual field projection and eyeglasses contour projection as analysis objects to realize non-contact and accurate comprehensive measurement of protective eyeglasses visual field.According to different detection requirements,the system can realize two detection schemes:rapid screening of qualified and unqualified eyeglasses,and measurement of visual field performance(visual field and visual field qualified rate).A standard head mode and two optical fiber light sources are used to simulate the ideal field of vision of eye protector when the eyes look straight ahead.By comparing the changes of the projection area before and after wearing eyeglasses,the qualification of the visual field of the eyeglasses can be determined quickly.Taking the projection image of the eyeglasses to be measured as the object of analysis,the image processing algorithms of image difference,object detection,defect repair and interference elimination are designed.The frame of eyeglasses is separated from the projection background and lens completely,and the adaptability and accuracy of image measurement to the environment are improved.According to the relationship of angle-tension between pupils and eyeglasses,the corresponding pupil position on the eyeglasses is located from the outline of the eyeglasses frame obtained by image processing,and the edge information of the eyeglasses frame is extracted and saved to complete the calculation of the relative visual field in the horizontal and vertical directions of the protective eyeglasses.According to the visual characteristics of the eyes when people look directly ahead,the human visual field is constructed by spatial transformation of the outline information of the eyeglasses,and the qualified rate of the relevant visual field of the protective eyeglasses is calculatedThe experimental results show that the method has the characteristics of high efficiency and intelligence compared with traditional methods.It only takes 10 second to determine qualification of the visual field of an eyeglasses.The error analysis of the measurement system is carried out and the final extended uncertainty of visual field measurement is U=0.8°(k=2),the standard deviation of repeatability measurement results of visual field qualification rate is less than 0.3%.The system meet the practical demand of the visual field detection of protective eyeglasses.