Adaptive Human Tracking Across Non-overlapping Cameras in Depression Angles

To track human across non-overlapping cameras in depression angles for applications such as multi-airplane visual human tracking and urban multi-camera surveillance,an adaptive human tracking method is proposed,focusing on both feature representation and human tracking mechanism.Feature representation describes individual by using both improved local appearance descriptors and statistical geometric parameters.The improved feature descriptors can be extracted quickly and make the human feature more discriminative.Adaptive human tracking mechanism is based on feature representation and it arranges the human image blobs in field of view into matrix.Primary appearance models are created to include the maximum inter-camera appearance information captured from different visual angles.The persons appeared in camera are first filtered by statistical geometric parameters.Then the one among the filtered persons who has the maximum matching scale with the primary models is determined to be the target person.Subsequently,the image blobs of the target person are used to update and generate new primary appearance models for the next camera,thus being robust to visual angle changes.Experimental results prove the excellence of the feature representation and show the good generalization capability of tracking mechanism as well as its robustness to condition variables.

Monte-Carlo simulation of pinhole collimator of a small field of view gamma camera for small animal imaging

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.

Color compensation for multi-view video coding based on diversity of cameras

A novel color compensation method for multi-view video coding (MVC) is proposed, which efficiently exploits the inter-view dependencies between views with the existence of color mismatch caused by the diversity of cameras. A color compensation model is developed in RGB channels and then extended to YCbCr channels for practical use. A modified inter-view reference picture is constructed based on the color compensation model, which is more similar to the coding picture than the original inter-view reference picture. Moreover, the color compensation factors can be derived in both encoder and decoder, therefore no additional data need to be transmitted to the decoder. The experimental results show that the proposed method improves the coding efficiency of MVC and maintains good subjective quality.

Constructing a Virtual Large Reference Plate with High-precision for Calibrating Cameras with Large FOV

It is well known that the accuracy of camera calibration is constrained by the size of the reference plate,it is difficult to fabricate large reference plates with high precision.Therefore,it is non-trivial to calibrate a camera with large field of view(FOV).In this paper,a method is proposed to construct a virtual large reference plate with high precision.Firstly,a high precision datum plane is constructed with a laser interferometer and one-dimensional air guideway,and then the reference plate is positioned at different locations and orientations in the FOV of the camera.The feature points of reference plate are projected to the datum plane to obtain a virtual large reference plate with high-precision.The camera is moved to several positions to get different virtual reference plates,and the camera is calibrated with the virtual reference plates.The experimental results show that the mean re-projection error of the camera calibrated with the proposed method is 0.062 pixels.The length of a scale bar with standard length of 959.778mm was measured with a vision system composed of two calibrated cameras,and the length measurement error is 0.389mm.

一种双视场电视/激光测距接收共光路一体化机设计

设计了一款双视场电视与激光测距接收共光路一体化机。根据应用需求,首先对CMOS、雪崩管器件选型;其次对光学、机械、电气部分进行设计,采用共用前物镜组,并利用镀有光谱分光膜的分光镜以及中继镜组,实现电视双视场与激光接收的共光路光学系统设计,电视大视场用于搜索目标,电视小视场用于跟踪目标,激光测距接收单元用于接收激光回波;然后采用主镜筒与整机壳体一体化设计,并以整体铸造方式进行加工,提高一体机整体结构强度;最后采用双H桥电机启动芯片并联设计,提高运行额定电流,并根据限位开关检测结果,实现电机对传动部件的精准限位控制。对设计结果进行分析,结果表明:设计的一体机大/小视场像质良好、像面稳定,激光测距接收单元工作状态良好。

大视场相机最优投影模型识别及星光标定方法

针对在轨摄影测量中近距离大尺寸测量需求,提出利用星光约束的大视场角摄影测量相机最优投影模型识别及标定方法。首先,构建了具备调节系数的星光几何投影分段函数模型。随后,针对分段星光投影模型开发多站位自标定光束平差算法。通过将光束平差算法与北方苍鹰寻优策略相结合,对投影模型调节系数、相机内方位参数、相机外方位参数及镜头畸变系数同步优化,直到星点像面重投影均方根误差达到全局最小,得到最优投影模型及其参数。实测实验表明,大视场角相机星光标定后,星点像面坐标的重投影均方根误差为1/9 pixel。在连续帧星光标定实验中,通过卡尔曼滤波算法对相机参数随机误差进行了有效消除。该方法可在相机星光标定过程中识别最优投影模型并标定全部成像参数,具备连续帧标定及参数校准能力。

一种大视场红外相机的畸变校正方法

本文针对大视场红外相机的畸变校正过程复杂的问题,提出了一种新的畸变校正方法。首先,选择单参数除法模型(division model,DM)作为相机畸变模型,使用改进的加速特征稳健算法(speed-up robust features,SURF)自动获取两幅有相同场景的畸变红外图像的特征点对,然后利用九点非迭代算法和核密度估计方法获取图像的畸变参数,最后根据求得的畸变参数使用基于边缘保持的灰度插值方法对图像进行畸变校正。在整个过程中,不需要预先知道相机的参数和场景信息,通过输入两幅具有相同场景的图像,完成畸变校正,为大视场红外相机的畸变校正提供了一种新的解决方法。实验结果表明,使用该方法对大视场红外相机进行畸变校正具有可行性和鲁棒性。

一种大视场高分辨率的复眼光学系统设计

针对传统无人机载成像系统无法实现大视场与高分辨率共存的问题,设计了一款大视场高分辨率无人机载复眼相机系统,该相机由曲面子眼阵列、光学中继系统和图像探测器三部分组成。中继系统使用了非球面设计,减小了系统体积。单个子眼焦距为20 mm,视场角为10°,中继系统为一鱼眼透镜,焦距为7 mm,可将子眼阵列所成焦曲面像转为平面像。总系统视场达到122°×106°,F数为3,焦距为3 mm,在飞行高度1 000 m时对地分辨率为0.8 m。仿真结果显示,各个光学子通道调制传递函数(modulation transfer function, MTF)在208 lp/mm处均大于0.3,系统在给定的公差范围内像质能够满足要求。与现有无人机载复眼系统相比,该文设计的系统视场更大,分辨率更高,且体积更小。

基于LabVIEW的图象检测系统的设计及应用

结合具体课题详细阐述基于LabVIEW的图象检测系统的设计方法 ;重点介绍CCD摄象系统设计的计算方法 ,数字图象处理软件的设计要点。

前挡风玻璃后方前视摄像头高精度标定算法研究

为解决光线经挡风玻璃折射导致的传统标定模型精度差的问题,根据光线折射规律和挡风玻璃姿态建立挡风玻璃的光线折射模型,开发一种前挡风玻璃后方前视相机的高精度标定新算法,并通过仿真试验和实车试验,证明新算法的标定精度显著提高。

乘员舱大角度飞行时间相机的设计与验证

针对汽车乘员舱飞行时间(TOF)相机可视角度小、无法兼顾前排所有成员等问题,提出一种TOF相机设计方案,通过热设计仿真的方式解决了TOF相机的散热问题,并通过对TOF相机镜头的光学设计与仿真,有效扩大了相机的视场角(FOV),同时进行了完整的设计验证试验,结果表明,该系统完整实现了TOF相机的功能,并可以大角度视场覆盖车内前排乘员,且满足车规级性能要求。

Effect of Source to Camera Distance and Count Rate on Intrinsic Uniformity of SPECT Gamma Camera

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.

Panoramic camera on the Yutu lunar rover of the Chang'e-3 mission

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.

Survey on path and view planning for UAVs

Background In recent decades,unmanned aerial vehicles(UAVs)have developed rapidly and been widely applied in many domains,including photography,reconstruction,monitoring,and search and rescue.In such applications,one key issue is path and view planning,which tells UAVs exactly where to fly and how to search.Methods With specific consideration for three popular UAV applications(scene reconstruction,environment exploration,and aerial cinematography),we present a survey that should assist researchers in positioning and evaluating their works in the context of existing solutions.Results/Conclusions It should also help newcomers and practitioners in related fields quickly gain an overview of the vast literature.In addition to the current research status,we analyze and elaborate on advantages,disadvantages,and potential explorative trends for each application domain.

高分六号卫星甚宽视场相机的热控设计及验证

甚宽视场相机作为高分六号卫星的核心载荷,具备65.6°视场、862 km超大幅宽和8谱段成像能力。针对其自由曲面离轴四反光学系统的结构特点和任务需求,采用复合型多层隔热组件进行热隔离、高导热率石墨膜进行热疏导及分级热控等措施进行了热控设计,实现了光机结构的精密控温和高热耗/热流密度电子学设备的高效散热,并利用有限元分析软件UG12.0/Space thermal仿真分析了相机高、低温工况下的温度;通过对比热分析、热试验及卫星在轨遥测温度数据,验证了该热控方案的实际效果。在轨遥测数据显示:光机结构在轨温度水平为19.7~20.3℃,温度梯度最大不超过0.4℃,CMOS焦面组件每轨摄像12 min的情况下,温度波动在19~24℃,均满足热控指标要求,遥测数据与热分析及热试验结果偏差小于±0.5℃。表明该相机热设计正确可行,热分析及热试验过程合理可靠。

一种三维人体模型快速测量方法

三维人体的逆向建模在服装领域具有重要应用价值,然而测量人体模型时难以保证长时间的固定姿态,且人体表面不能喷涂纹理特征,急需实现非接触的人体模型高精度快速测量。该文提出一种数字散斑投射的高精度快速扫描方法,通过十参数畸变模型,实现相机的高精度标定;利用双目立体视觉原理,构建三维人体快速扫描的传感测量装置;通过大视场标定与坐标统一技术,结合彩色摄像机和散斑投影仪实现包含面部的人体全方位多视角图像;利用立体视觉重建技术重建得到完整的三维人体点云模型,并进行点云后处理。通过实验验证该文方法标定15次得到的重投影误差,测量结果均优于0.05 pixels,说明所提出的三维人体快速测量方法测量精度高。3组人体扫描实验结果充分表明:该文提出的方法可以在0.1 s内完成人体扫描,并且校准误差均小于0.1 pixels,可以实现对人体的快速、高精度扫描。

双平面镜辅助多视角数字图像相关方法的研究进展及应用

双平面镜辅助多视角数字图像相关方法(multi-view digital image correlation,MV-DIC)是DIC技术用于全景或双表面形貌和变形测量的新分支。传统的MV-DIC需要两套或多套同步的双目3D-DIC系统,而双平面镜辅助MV-DIC仅需要一套常规3D-DIC系统和两个平面反射镜,其系统成本低和易于实现等优点使其在常规尺寸试样的全景/双表面变形测量任务中可完全替代前者。本文介绍了作者近期在双平面镜辅助MV-DIC研究中取得的新进展,包括两种新型的双平面镜辅助MV-DIC系统和一种基于荧光散斑的平面镜反射变换标定方法。最后介绍了双平面镜辅助MV-DIC在含缺陷蜂窝合金板面内压缩、手机跌落以及管道高速振动双平面/全景变形测量中的应用。

基于弱随机相机位姿图像的三维场景恢复

随着深度学习的快速发展,基于多视图的三维场景恢复研究和应用越来越广泛。许多研究者关注通过优化深度学习网络提高三维场景恢复效果,深度学习使用的训练数据集的相机位姿分布具有规范度高的内在特点。然而在实际应用中,普通用户拍摄目标场景时,相机位姿分布具有较大的随机性,难以保证获取到和训练数据集质量等同或接近的目标场景图像数据,从而影响恢复效果。为了缓解这一问题,该文提出了基于弱随机相机位姿图像的三维场景恢复方法,通过给用户提供目标场景拍摄建议,降低所获取目标场景图像相机位姿分布的随机性,提高场景的三维恢复效果。首先,用户在目标场景拍摄指导下,获得同一场景下不同视角的二维图像数据,然后通过SFM(Structure From Motion)恢复场景的三维稀疏点云和相机位姿,最后在MVS(Multi-View Stereo)网络模型中进行三维点云的稠密重建。实验结果表明,相比拍摄建议前,该方法有效降低了所获取目标场景图像相机位姿分布的随机性,三维场景恢复成功率提高了52.95%。

北京三号B卫星相机像质评价方法

光学遥感相机的静态传递函数测试需要配套适当口径的平行光管,制造难度大、成本高,无法满足高性能、低成本的商业遥感载荷研制需求。文章提出一种基于异视场准直光路的像质评价方法,使用相机光学系统自身光路作为测试系统,通过异视场光路的准直,测得相机异视场叠加像质,对测试结果进行数据解算,最终得出相机各视场的真实波前信息。以北京三号B卫星相机研制过程为例,利用相机光学系统与自准直反射镜系统配合,采用上述异视场共光路测试方法,测量结果与传统方法测试结果进行对照,结果表明该方法测试结果准确、切实可行。