The integration of the Lab model with the extended histogram of oriented gradients （EHOG） is proposed to improve the accuracy of human appearance matching across disjoint camera views under perturbations such as ill...The integration of the Lab model with the extended histogram of oriented gradients （EHOG） is proposed to improve the accuracy of human appearance matching across disjoint camera views under perturbations such as illumination changes and different viewing angles. For the Lab model that describes the global information of observations, a sorted nearest neighbor clustering method is proposed for color clustering and then a partitioned color matching method is used to calculate the color similarity between observations. The Bhattacharya distance is employed for the textural similarity calculation of the EHOG which describes the local information. The global information, which is robust to different viewing angles and scale changes, describes the observations well. Meanwhile, the use of local information, which is robust to illumination changes, can strengthen the discriminative ability of the method. The integration of global and local information improves the accuracy and robustness of the proposed matching approach. Experiments are carried out indoors, and the results show a high matching accuracy of the proposed method.展开更多
Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collim...Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collimator must keep a compromise between spatial resolution and sensitivity.In order to design a pinhole collimator with an optimized sensitivity and spatial resolution,the spatial resolution and the geometric sensitivity response as a function of the source to collimator distance has been obtained by means of Monte-Carlo simulation for a small field of view gamma camera with a pinhole collimator of various-hole diameters.The results show that the camera with pinhole of 1 mm,1.5 mm and 2 mm diameter has respectively spatial resolution of 1.5 mm,2.25 mm and 3 mm and geometric sensitivity of 0.016%,0.022%and 0.036%,while the source to collimator distance is 3 cm.We chose the pinhole collimator with hole diameter size of 1.2 mm for our the gamma camera designed based on the trade-off between sensitivity and resolution.展开更多
针对内埋舱武器性能鉴定试飞中机弹分离相对位姿测量需求,提出了一种基于高速影像的内埋舱武器分离位姿测量方法。通过加装带有弯管镜头的高速摄像机阵列,实现内埋弹舱狭小空间内弹体分离全过程高速影像数据的分段获取;采用结合机载空...针对内埋舱武器性能鉴定试飞中机弹分离相对位姿测量需求,提出了一种基于高速影像的内埋舱武器分离位姿测量方法。通过加装带有弯管镜头的高速摄像机阵列,实现内埋弹舱狭小空间内弹体分离全过程高速影像数据的分段获取;采用结合机载空间参考点不确定性的相机外参解算、基于You Only Look Once version 8(YOLOv8)的标志点智能检测、基于边缘灰度梯度正交迭代的十字标中心坐标自动提取、直线约束下的多视角非交叠影像测量等方法,实现机载高速摄像机分布快速标定、小视场成像条件下弹体表面标志点亚像素坐标自动提取、机载高速摄像机抖动下的外参动态修正以及武器分离相对位姿分段测量等功能。经地面试验验证,该方法位置解算均方根误差不大于2 mm,满足飞行试验测试精度要求。展开更多
The Chang＇e-3 panoramic camera, which is composed of two cameras with identical functions, performances and interfaces, is installed on the lunar rover mast. It can acquire 3D images of the lunar surface based on the...The Chang＇e-3 panoramic camera, which is composed of two cameras with identical functions, performances and interfaces, is installed on the lunar rover mast. It can acquire 3D images of the lunar surface based on the principle of binocular stereo vision. By rotating and pitching the mast, it can take several photographs of the patrol area. After stitching these images, panoramic images of the scenes will be obtained.Thus the topography and geomorphology of the patrol area and the impact crater, as well as the geological structure of the lunar surface, will be analyzed and studied.In addition, it can take color photographs of the lander using the Bayer color coding principle. It can observe the working status of the lander by switching between static image mode and dynamic video mode with automatic exposure time. The focal length of the lens on the panoramic camera is 50 mm and the field of view is 19.7？umination and viewing conditions, the largest signal-to-no×14.5？.Under the best illise ratio of the panoramic camera is 44 d B. Its static modulation transfer function is 0.33. A large number of ground testing experiments and on-orbit imaging results show that the functional interface of the panoramic camera works normally. The image quality of the panoramic camera is satisfactory. All the performance parameters of the panoramic camera satisfy the design requirements.展开更多
In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and ...In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and differential intrinsic uniformity tests for both Useful Field Of View (UFOV) and Centre Field Of View (CFOV) were done by insertion a point-source of 99mTc in front of the detectors with detached collimators to measure the effect of source to camera distance and a count rate on intrinsic uniformity. The result reveals that the best intrinsic uniformity image is obtained at source-to-camera distance of 3 m and a count rate between 16 and 60 M.展开更多
To fulfill the need for acquiring three-dimensional(3D) objects with more realistic textures and depth information, this study proposes a method based on near-infrared laser, combined with dual camera field of view ce...To fulfill the need for acquiring three-dimensional(3D) objects with more realistic textures and depth information, this study proposes a method based on near-infrared laser, combined with dual camera field of view center correction and binocular stereo calibration, to precisely capture the target surface texture. Furthermore, we constructed a verification system using standard industrial cameras and line lasers, achieving the generation of binocular line laser point cloud real textures. Experiments conducted within a 400 mm to 600 mm testing range achieved a reconstruction accuracy of 0.047 2 mm and reduced the texture mapping error to 0.323 4 pixel, proving the effectiveness of this method and providing a high-precision, low-cost solution for 3D point cloud model texture mapping.展开更多
基金The National Natural Science Foundation of China(No.60972001)the Science and Technology Plan of Suzhou City(No.SG201076)
文摘The integration of the Lab model with the extended histogram of oriented gradients （EHOG） is proposed to improve the accuracy of human appearance matching across disjoint camera views under perturbations such as illumination changes and different viewing angles. For the Lab model that describes the global information of observations, a sorted nearest neighbor clustering method is proposed for color clustering and then a partitioned color matching method is used to calculate the color similarity between observations. The Bhattacharya distance is employed for the textural similarity calculation of the EHOG which describes the local information. The global information, which is robust to different viewing angles and scale changes, describes the observations well. Meanwhile, the use of local information, which is robust to illumination changes, can strengthen the discriminative ability of the method. The integration of global and local information improves the accuracy and robustness of the proposed matching approach. Experiments are carried out indoors, and the results show a high matching accuracy of the proposed method.
基金Supported by National Foundation of Nature Science of China(No.10275063)
文摘Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collimator must keep a compromise between spatial resolution and sensitivity.In order to design a pinhole collimator with an optimized sensitivity and spatial resolution,the spatial resolution and the geometric sensitivity response as a function of the source to collimator distance has been obtained by means of Monte-Carlo simulation for a small field of view gamma camera with a pinhole collimator of various-hole diameters.The results show that the camera with pinhole of 1 mm,1.5 mm and 2 mm diameter has respectively spatial resolution of 1.5 mm,2.25 mm and 3 mm and geometric sensitivity of 0.016%,0.022%and 0.036%,while the source to collimator distance is 3 cm.We chose the pinhole collimator with hole diameter size of 1.2 mm for our the gamma camera designed based on the trade-off between sensitivity and resolution.
文摘针对内埋舱武器性能鉴定试飞中机弹分离相对位姿测量需求,提出了一种基于高速影像的内埋舱武器分离位姿测量方法。通过加装带有弯管镜头的高速摄像机阵列,实现内埋弹舱狭小空间内弹体分离全过程高速影像数据的分段获取;采用结合机载空间参考点不确定性的相机外参解算、基于You Only Look Once version 8(YOLOv8)的标志点智能检测、基于边缘灰度梯度正交迭代的十字标中心坐标自动提取、直线约束下的多视角非交叠影像测量等方法,实现机载高速摄像机分布快速标定、小视场成像条件下弹体表面标志点亚像素坐标自动提取、机载高速摄像机抖动下的外参动态修正以及武器分离相对位姿分段测量等功能。经地面试验验证,该方法位置解算均方根误差不大于2 mm,满足飞行试验测试精度要求。
文摘The Chang＇e-3 panoramic camera, which is composed of two cameras with identical functions, performances and interfaces, is installed on the lunar rover mast. It can acquire 3D images of the lunar surface based on the principle of binocular stereo vision. By rotating and pitching the mast, it can take several photographs of the patrol area. After stitching these images, panoramic images of the scenes will be obtained.Thus the topography and geomorphology of the patrol area and the impact crater, as well as the geological structure of the lunar surface, will be analyzed and studied.In addition, it can take color photographs of the lander using the Bayer color coding principle. It can observe the working status of the lander by switching between static image mode and dynamic video mode with automatic exposure time. The focal length of the lens on the panoramic camera is 50 mm and the field of view is 19.7？umination and viewing conditions, the largest signal-to-no×14.5？.Under the best illise ratio of the panoramic camera is 44 d B. Its static modulation transfer function is 0.33. A large number of ground testing experiments and on-orbit imaging results show that the functional interface of the panoramic camera works normally. The image quality of the panoramic camera is satisfactory. All the performance parameters of the panoramic camera satisfy the design requirements.
文摘In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and differential intrinsic uniformity tests for both Useful Field Of View (UFOV) and Centre Field Of View (CFOV) were done by insertion a point-source of 99mTc in front of the detectors with detached collimators to measure the effect of source to camera distance and a count rate on intrinsic uniformity. The result reveals that the best intrinsic uniformity image is obtained at source-to-camera distance of 3 m and a count rate between 16 and 60 M.
基金supported by the Program for Innovative Research Team in University of Tianjin (No.TD13-5036)the Tianjin Science and Technology Popularization Project (No.22KPXMRC00090)。
文摘To fulfill the need for acquiring three-dimensional(3D) objects with more realistic textures and depth information, this study proposes a method based on near-infrared laser, combined with dual camera field of view center correction and binocular stereo calibration, to precisely capture the target surface texture. Furthermore, we constructed a verification system using standard industrial cameras and line lasers, achieving the generation of binocular line laser point cloud real textures. Experiments conducted within a 400 mm to 600 mm testing range achieved a reconstruction accuracy of 0.047 2 mm and reduced the texture mapping error to 0.323 4 pixel, proving the effectiveness of this method and providing a high-precision, low-cost solution for 3D point cloud model texture mapping.
