共查询到20条相似文献,搜索用时 156 毫秒
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基于新型靶的CCD摄像系统畸变测量与校正 总被引:2,自引:2,他引:2
深入研究了测试图案对测量畸变的影响。提出"一靶测试法"进行畸变测量与校正,拍摄了自行设计、制作的"综合点阵靶板"的畸变图像,图像处理得到其畸变点位置,并与理想点位置进行对应比较。建立多项式模型确定畸变点与理想点的位置校正关系,理想点位置由理想成像得到,并运用最小二乘拟合算法求得多项式系数,标定整个CCD摄像系统的畸变。"综合点阵靶板"采用灰色圆点黑色间带图案,方便了点按序标记排列,从而确定畸变点与理想点的一一对应。对2.6 mm焦距的广角CCD镜头摄像系统进行了畸变测量与校正,其重复测量,校正精度达到0.3%。 相似文献
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设计了一种基于点结构光的腹部运动测量系统,用于监测由呼吸运动引起的患者腹部实时状态,为主动补偿放疗中因呼吸因素造成的靶区位移、实现靶区的相对静止提供精确位置信息。测量系统基于激光三角测量原理的点结构原理,将腹部运动转换为激光点移动,从相机记录下的图像中提取激光点位置,根据已知系统参数即可从激光点的移动量计算得到每个时刻呼吸所引起的腹部运动量。实验表明,所提方法能准确、实时地获取位置信息,具有结构简单、精度高等优点,能为胸腹动态放疗中患者呼吸因素的补偿提供一种新的解决方法。 相似文献
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图像序列中目标关键帧快速搜索算法 总被引:3,自引:1,他引:2
在目标测量时所获得的图像序列中,如何定位目标关键帧(最有利于目标测量的图像)的位置,对目标识别的效率和测量设备的性能有着显著的影响.针对具有复杂特性的目标图像序列,提出了一种基于帧间像素灰度差值来定位目标关键帧的快速搜索算法.该算法仅仅利用像素灰度值这一最基本的特征,将图像序列中相邻两张图像的同一像素的灰度差值与给定阈值相比较,统计高于阈值的像素个数,再与另一给定阈值相比较,进而确定目标关键帧的位置.实验结果表明,该算法对目标大小不同、形状不同,环境不同,信噪比较高的图像序列都具有快速、稳定的搜索效果. 相似文献
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航天器对接相对位置姿态自主测量方法研究 总被引:2,自引:0,他引:2
航天器间相对位置姿态的准确测量是实现自主自动对接的先决条件。将三圆标志靶安装在目标航天器上;追踪航天器用数码相机对靶拍照。设计了亚像素处理方法实时处理数字照片,可精确测定圆心像点位置和特征直径的像长;用其作为基本特征参数,基于透视投影原理,建立了求圆心物空间坐标的公式,求出靶面的平面方程,可用来求两航天器间的相对位置姿态参数和实时标定相机的可变参数。计算机仿真结果表明,测距为2m时,测圆心像点位置的误差小于0.03个像素,测距误差小于1mm,测姿态角的误差小于0.01°。该方法也适用于无人直升飞机定点着陆时自主测量其相对位姿参数。 相似文献
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基于计算机视觉的航天器间相对状态测量系统 总被引:10,自引:1,他引:9
在航天器编队飞行应用中,航天器间相对状态(相对位置和姿态)的确定是实现航天器自主控制的重要条件。通过充分利用计算机视觉理论及相机成像原理,提出了一种基于计算机视觉的航天器间相对状态的测量系统。推导了基于目标靶特征点确定航天器相对状态的四元数法,介绍了系统的测试原理及标定方法,并通过采用APSCMOS相机作为图像传感器,建立了它的试验原型,验证了测量原理和算法的正确性。该测量系统结构简单、体积小、重量轻、功耗低、算法简单、速度快,近距离测量精度高,能够广泛地应用于空间合作目标间相对状态的测量。 相似文献
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基于Mask R-CNN模型,对惯性约束聚变实验研究中靶图进行关键结构的语义分割,通过计算中心来定位目标靶点位置,通过模拟靶图数据来验证算法的可行性。在算法验证过程中通过程序批量生成不同结构参数、不同角度的模拟靶图作为数据集,然后通过增噪、成像位置变换等操作拓展样本数量。在大样本数量基础上对算法模型进行训练测试,实现语义分割,通过计算注入孔的中心得到目标靶点位置。测试结果显示准确率和召回率均在97%以上,在靶点识别精度上优于10个像素点。 相似文献
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A. H. Taub 《General Relativity and Gravitation》1979,10(12):1009-1009
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Ugeda MM Fernández-Torre D Brihuega I Pou P Martínez-Galera AJ Pérez R Gómez-Rodríguez JM 《Physical review letters》2011,107(11):116803
Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural, and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in freestanding graphene layers. 相似文献
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We study the relation between the centro-affine geometry of star-shaped planar curves and the projective geometry of parametrized maps into RP1. We show that projectivization induces a map between differential invariants and a bi-Poisson map between Hamiltonian structures. We also show that a Hamiltonian evolution equation for closed star-shaped planar curves, discovered by Pinkall, has the Schwarzian KdV equation as its projectivization. (For both flows, the curvature evolves by the KdV equation.) Using algebro-geometric methods and the relation of group-based moving frames to AKNS-type representations, we construct examples of closed solutions of Pinkall’s flow associated with periodic finite-gap KdV potentials. 相似文献
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In this note we use some of the results of [3] to derive a general duality theorem for the cohomologies of foliated structures on a manifold. The result is applied to the special case of a symplectic manifold M on which the foliation is given by a complex polarization F in the sense of geometric quantization. We obtain, for example, a rigorous proof of the fact that for a smooth function ƒ on M whose Hamiltonian vector field leaves F invariant, the spectrum of the corresponding prequantization operator v(ƒ) coincides with the spectrum of its transpose, under the above duality. This latter result was obtained by Simms in [12] under certain hypotheses. Proofs of the validity of those hypotheses are now available in the literature; cf. [3] and [7]. 相似文献
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Valfells A. Verboncoeur J.P. Lau Y.Y. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(3):529-536
Analyzes the effects of space charge shielding on the steady state of a multipactor discharge on a dielectric. Analytic methods are used to obtain an exact function for the potential in the discharge, assuming a Maxwellian distribution of emitted electrons. An equation for the amount of power deposited on the dielectric by the multipactoring electrons, for a given saturation level, is given. A simple method for obtaining the saturation level, for a given material, is obtained 相似文献
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