目的通过对6~14周岁儿童青少年近视眼各项调节参数的分析,为近视的防控提供理论依据。方法前瞻性病例对照研究。选择2017年12月至2019年12月在我屈光中心建立视觉发育档案的儿童青少年200例(400只眼),按屈光度等效球镜(SE)分为3组:轻度...目的通过对6~14周岁儿童青少年近视眼各项调节参数的分析,为近视的防控提供理论依据。方法前瞻性病例对照研究。选择2017年12月至2019年12月在我屈光中心建立视觉发育档案的儿童青少年200例(400只眼),按屈光度等效球镜(SE)分为3组:轻度近视(SE≤-3.00 D 92例),中度近视(-3.00 D<SE≤-6.00 D 80例)、高度近视(SE>-6.00 D 28例)。测量矫正视力、屈光度、调节幅度(AMP)、调节反应(BCC)、正、负相对调节(PRA/NRA)、调节灵敏度(AF)。结果3组屈光度不同的近视,AMP调节幅度均低于该年龄段平均值,其中高度近视组与低、中度近视组调节幅度的差异均有统计学意义(均P<0.01);BCC随屈光度不同,调节超前和调节滞后所占的比例差异具有统计学意义(P<0.01);PRA低度近视组与中度近视组差异(P<0.05),与高度近视组差异(P<0.01),二者差异均有统计学意义;NRA各组之间无统计学差异;AF高度近视组与低、中度组之间差异均有统计学意义(均P<0.01)。结论建立儿童及青少年视觉发育档案,可以从多方面了解患儿视觉发育的变化,从而为近视的防控提供个体化连续动态的观察。展开更多
The mathematic model of the line structured-light 3-D vision sensor was established.A separating-parameter method was proposed to calibrate the structure parameter,and a calibration target was designed.In the calibrat...The mathematic model of the line structured-light 3-D vision sensor was established.A separating-parameter method was proposed to calibrate the structure parameter,and a calibration target was designed.In the calibrating process,complicated measurement is avoided and the calibration is fast and easy to carry out,which simplifies the calibrating procedure.The experimental results show that the space measurement accuracy is better than 0.15 mm.This method is high efficient and practical in vision sensors calibration.展开更多
Many Internet-GIS have been implemented on the web and they are increasingly becoming an important part of multimedia cartography that has much more users as compared to traditional GIS production media.Internet GIS t...Many Internet-GIS have been implemented on the web and they are increasingly becoming an important part of multimedia cartography that has much more users as compared to traditional GIS production media.Internet GIS technology has provided the GIS dynamic information acquisition with technical support.Also,the visualization technology of electronic map has provided tools for GIS symbols with dynamic characteristics.On the basis of GIS dynamic information acquisition,the design idea and implementation methods of dynamic symbols in dynamic GIS are presented in this article.展开更多
Light pen coordinate measuring system(LPCMS)is a kind of portable coordinate measuring technique based on vision metrology.In classical LPCMS,the measuring range is limited to the camera’s field of view.To overcome t...Light pen coordinate measuring system(LPCMS)is a kind of portable coordinate measuring technique based on vision metrology.In classical LPCMS,the measuring range is limited to the camera’s field of view.To overcome this defect,a new LPCMS is designed in this paper to fulfil whole space coordinate measurement.The camera is installed on a turntable instead of a tripod,so that the camera can rotate to track the movement of the light pen.The new system can be applied to large scale onsite measurement,and therefore it notably extends the application of LPCMS.To guarantee the accuracy of the new system,a method to calibrate the parameters of the tracking turntable is also proposed.Fixing the light pen at a stationary position,and changing the azimuth angles of the turntable’s two shafts,so that the camera can capture the images of the light pen from different view angles.According to the invariant spatial relationship between the camera and the pedestal of the tracking turntable,a system of nonlinear equations can be established to solve the parameters of the turntable.Experimental results show that the whole space coordinate measuring accuracy of the new system can reach 0.25 mm within 10 m.It can be concluded that the newly designed system can significantly expand the measuring range of LPCMS without losing too much accuracy.展开更多
Pose and structure estimation from a single image is a fundamental problem in machine vision and multiple sensor fusion and integration. In this paper we propose using rigid constraints described in different coordina...Pose and structure estimation from a single image is a fundamental problem in machine vision and multiple sensor fusion and integration. In this paper we propose using rigid constraints described in different coordinate frames to iteratively estimate structural and camera pose parameters. Using geometric properties of reflected correspondences we put forward a new concept, the reflected pole of a rigid transformation. The reflected pole represents a general analysis of transformations that can be applied to both 2D and 3D transformations. We demonstrate how the concept is applied to calibration by proposing an iterative method to estimate the structural parameters of objects. The method is based on a coarse-to-fine strategy in which initial estimation is obtained through a classical linear algorithm which is then refined by iteration. For a comparative study of performance, we also implemented an extended motion estimation algorithm (from 2D-2D to 3D-2D case) based on epipolar geometry.展开更多
Article use Visual LISP development tools and DCL dialog technology, which implements the standard straight teeth, a two- dimensional cylindrical gear paranaetric drawing on AutoCAD platform, with easy to operate and ...Article use Visual LISP development tools and DCL dialog technology, which implements the standard straight teeth, a two- dimensional cylindrical gear paranaetric drawing on AutoCAD platform, with easy to operate and improve design efficiency. We achieved that using the dialog box design input parameters, and gear parts of the design calculations, parameters proofreading and all kinds of gear design drawing different structures by programming. The output is fully automated computer-aided design system. The results show that the design of the system significantly improves the efficiency of the part design.展开更多
文摘目的通过对6~14周岁儿童青少年近视眼各项调节参数的分析,为近视的防控提供理论依据。方法前瞻性病例对照研究。选择2017年12月至2019年12月在我屈光中心建立视觉发育档案的儿童青少年200例(400只眼),按屈光度等效球镜(SE)分为3组:轻度近视(SE≤-3.00 D 92例),中度近视(-3.00 D<SE≤-6.00 D 80例)、高度近视(SE>-6.00 D 28例)。测量矫正视力、屈光度、调节幅度(AMP)、调节反应(BCC)、正、负相对调节(PRA/NRA)、调节灵敏度(AF)。结果3组屈光度不同的近视,AMP调节幅度均低于该年龄段平均值,其中高度近视组与低、中度近视组调节幅度的差异均有统计学意义(均P<0.01);BCC随屈光度不同,调节超前和调节滞后所占的比例差异具有统计学意义(P<0.01);PRA低度近视组与中度近视组差异(P<0.05),与高度近视组差异(P<0.01),二者差异均有统计学意义;NRA各组之间无统计学差异;AF高度近视组与低、中度组之间差异均有统计学意义(均P<0.01)。结论建立儿童及青少年视觉发育档案,可以从多方面了解患儿视觉发育的变化,从而为近视的防控提供个体化连续动态的观察。
基金Supported by the National Natural Science Foundation of China(No.50235030)
文摘The mathematic model of the line structured-light 3-D vision sensor was established.A separating-parameter method was proposed to calibrate the structure parameter,and a calibration target was designed.In the calibrating process,complicated measurement is avoided and the calibration is fast and easy to carry out,which simplifies the calibrating procedure.The experimental results show that the space measurement accuracy is better than 0.15 mm.This method is high efficient and practical in vision sensors calibration.
文摘Many Internet-GIS have been implemented on the web and they are increasingly becoming an important part of multimedia cartography that has much more users as compared to traditional GIS production media.Internet GIS technology has provided the GIS dynamic information acquisition with technical support.Also,the visualization technology of electronic map has provided tools for GIS symbols with dynamic characteristics.On the basis of GIS dynamic information acquisition,the design idea and implementation methods of dynamic symbols in dynamic GIS are presented in this article.
基金State Administration of Science,Technology and Industry for the National Defense(No.JSJL2014206B001)。
文摘Light pen coordinate measuring system(LPCMS)is a kind of portable coordinate measuring technique based on vision metrology.In classical LPCMS,the measuring range is limited to the camera’s field of view.To overcome this defect,a new LPCMS is designed in this paper to fulfil whole space coordinate measurement.The camera is installed on a turntable instead of a tripod,so that the camera can rotate to track the movement of the light pen.The new system can be applied to large scale onsite measurement,and therefore it notably extends the application of LPCMS.To guarantee the accuracy of the new system,a method to calibrate the parameters of the tracking turntable is also proposed.Fixing the light pen at a stationary position,and changing the azimuth angles of the turntable’s two shafts,so that the camera can capture the images of the light pen from different view angles.According to the invariant spatial relationship between the camera and the pedestal of the tracking turntable,a system of nonlinear equations can be established to solve the parameters of the turntable.Experimental results show that the whole space coordinate measuring accuracy of the new system can reach 0.25 mm within 10 m.It can be concluded that the newly designed system can significantly expand the measuring range of LPCMS without losing too much accuracy.
文摘Pose and structure estimation from a single image is a fundamental problem in machine vision and multiple sensor fusion and integration. In this paper we propose using rigid constraints described in different coordinate frames to iteratively estimate structural and camera pose parameters. Using geometric properties of reflected correspondences we put forward a new concept, the reflected pole of a rigid transformation. The reflected pole represents a general analysis of transformations that can be applied to both 2D and 3D transformations. We demonstrate how the concept is applied to calibration by proposing an iterative method to estimate the structural parameters of objects. The method is based on a coarse-to-fine strategy in which initial estimation is obtained through a classical linear algorithm which is then refined by iteration. For a comparative study of performance, we also implemented an extended motion estimation algorithm (from 2D-2D to 3D-2D case) based on epipolar geometry.
文摘Article use Visual LISP development tools and DCL dialog technology, which implements the standard straight teeth, a two- dimensional cylindrical gear paranaetric drawing on AutoCAD platform, with easy to operate and improve design efficiency. We achieved that using the dialog box design input parameters, and gear parts of the design calculations, parameters proofreading and all kinds of gear design drawing different structures by programming. The output is fully automated computer-aided design system. The results show that the design of the system significantly improves the efficiency of the part design.
