采用棋盘格模板的摄像机标定新方法

在分析Opencv摄像机模型和现有的双目视觉系统标定方法的基础上,提出了一种新的标定算法.该算法包括3个步骤,首先利用最小二乘法求解图像的像面中心坐标,在不考虑畸变的情况下,选取中心处一小块作为摄像机标定的初始空间,采用线性优化方法求出除畸变系数以外的其他摄像机内外参数;然后将求得的参数作为初值,利用线性优化方法求解畸...     

基于HALCON的摄像机标定

利用HALCON图像处理软件提供的标定板模板,并充分考虑了透镜的径向畸变影响及求解方法,给出了基于HALCON的摄像机标定算法。该算法充分发挥了HALCON的函数库功能,提高了标定精度和计算效率,具有良好的跨平台移植性,可满足各种计算机视觉系统的需要。     

基于空间三角形的摄像机标定新算法

文章提出了一种基于空间三角形的摄像机标定算法.使用空间三角形作为标定物,将其绕一顶点自由转动并拍摄2幅以上标定图片,然后利用三角形三边长度信息作为约束条件建立线性方程组以求解摄像机的内参数.实验表明该算法制作标定模型简单,具有较高的精度和较好的鲁棒性.     

光学定位系统中摄像机标定的研究

在被动式光学定位系统中,CCD摄像机的标定是一个极其重要的过程。CCD摄像机的标定过程实际上是求解摄像机内、外参数的过程。基于基本矩阵的摄像机标定方法是根据极线约束、本质矩阵以及基本矩阵之间的关系,利用传统的8点算法得到基本矩阵的初始值,再通过其他匹配点迭代计算摄像机的径向阶畸变和切向畸变系数,最后由得到的畸变系数值计算校正后的基本矩阵,从而实现对畸变图像进行校正。     

智能CMM系统中摄像机的标定方法

将计算机视觉引入到坐标测量系统中能够实现零件位姿的识别.在建立一阶径向畸变摄像机模型的基础上,分析并得到了需要标定才能确知的摄像机内外部参数,对求解这些参数的方法和步骤进行了详细说明,结合坐标测量机(CMM)精度高的特点及白色陶瓷标准球的良好光学特性提出了一种基于摄像机平动的非共面标定方法.标定实验及结果分析表明该标定方法最终在X、Y方向上所引起的误差小于0.4994mm.     

基于正交消隐点无穷单应的摄像机内参数自标定方法

利用正交消隐点的几何特性和不同位姿摄像机图像平面中对应消隐点间的无穷单应关系,提出了一种摄像机内参数的自标定方法。该方法在任意两个位置下拍摄两组正交平行线,获取两幅图像上共四个消隐点后,设计了判定算法确定其间的对应情况。利用对应消隐点之间的无穷单应关系,结合正交消隐点与摄像机光心连线的正交性建立约束方程,实现了对摄像机内参数的线性求解。为了抑制噪声对标定结果的影响,建立基于矩形成像反演点特性的指标函数,利用LM寻优算法实现了对内参数的非线性优化。实验结果表明,该算法具有对应消隐点判断简单有效,标定结果精度高、实时性强、适用范围广的优点,而且参数优化能够有效地抑制图像噪声,提高了标定算法的稳健性。     

基于单幅立方体图的摄像机内参数标定

从图像中物体的度量结构确定摄像机内参数是不可缺少的步骤。根据透视投影正交灭点的形成原理和摄像机线性标定原理,提出一种基于灭点的摄像机标定方法。该方法的靶标为立方体,只需要单幅图像所获得的正交灭点即可线性地求解摄像机的内参数。实验表明,该算法能准确、可靠地估计摄像机的内参数,并与实际情况吻合得较好。     

一种获取摄像机安装高度及倾角的简易标定方法

提出了一种在摄像机内参数已知的情况下,通过地面上已知的4个及以上共面点求解出摄像机安装高度和安装倾角的标定方法.选定地面为X-O-Y面,则Z轴方向的平移因子即为摄像机的安装高度.方法借鉴了利用共面点进行标定的方法,在计算过程中利用投影矩阵元素间的比值关系,巧妙地消除了深度因子的影响,求解出了旋转角度和摄像机的安装高度,进而得到了摄像机的外参数矩阵.将多组实验计算出的安装高度结果和实际测量值相对比,得到的误差非常小,证明了该算法计算简便且具有较高的准确性.     

激光切割视觉系统单目摄像机快速标定方法

针对目前激光切割机结合视觉切割行业中现有的张正友一般圆点标定算法中存在计算量大、结果不稳定的问题。提出一种基于九圆点的摄像机自标定算法。算法首先计算出图像和定义在世界坐标系X-Y平面上的模板之间的单应性矩阵,利用该单应性矩阵线性求解出摄像机内参,然后考虑非线性畸变因素,求解出畸变系数。最后在矫正后的模板中求出内外共八个仿射投影矩阵,并取其均值做为最终投影矩阵来求解出世界坐标。实验结果表明:该算法比现有的基于圆点的摄像机自标定算法更快速、更稳定,达到精度更高。     

偏振探测系统的摄像机标定与图像畸变校正研究

偏振探测在许多相关领域的应用日益广泛,探测系统的标定及校准是精确提取被探目标的前提.本文针对偏振探测系统,分析了基于2D平面标靶的摄像机标定算法,建立了摄像机线性模型和非线性畸变模型,通过线性及非线性结合的算法,得到了精确的摄像机内外部参数.利用镜头的畸变模型,提出了一种采用牛顿迭代算法来求解高阶非线性方程组对图像畸变校正的方法,建立了各像素点畸变量与到畸变中心距离的关系,最后对畸变校正前后的图像进行了测试实验,测试结果表明:测试点实际畸变大小符合理论畸变量关系,很好地验证了镜头的径向畸变特性;经畸变校正后的偏振图像能有效提高被探目标提取的准确率,偏振图像的畸变校正对复杂背景下目标提取准确率的影响最明显.     

CCD摄像机参数标定实验设计

CCD摄像机标定技术是视觉检测技术中的最基本内容,为有助于学生正确理解和掌握视觉检测技术,本文设计了CCD摄像机参数的标定实验。详细介绍了CCD摄像机透视成像模型、RAC标定方法以及标定点空间坐标和图像坐标的获取方法,结合标定软件讲述了标定的主要步骤。     

基于球与圆特征的球体姿态估计

给出一种综合运用球及径向圆特征的球体姿态视觉检测新方法.不需特殊标定物,仅通过球及其中轴的单一视图,目标的3D位置及相机内参数可同时得到估计.算法依据球及圆特殊的位置关系,给出一种新的正交不变量,提供对IAC的线性约束,配合同心圆与自然相机约束,从而使相机定标及目标检测的线性求解成为可能;此外,基于样本点与重构椭圆几何误差测度的非线性最小二乘算法则进一步提高了估计结果的精确度.仿真及实际图像处理结果验证了算法的有效性.     

线阵CCD相机镜头畸变标定方法

针对线阵CCD相机标定时镜头会产生畸变的情况,提出来一种利用交比不变的方法,考虑镜头同时存在的径向畸变和离心畸变,对畸变参数进行标定,建立畸变校正函数,并利用Matlab做出镜头畸变曲线,分析了线阵CCD相机镜头仅仅存在径向畸变时对结果的影响和径向畸变与离心畸变都存在时的影响。这种方法应用于相机标定之前,可以有效地消除线阵CCD相机镜头误差对整体标定结果的影响。     

A high-precision camera operation parameter measurement system andits application to image motion inferring

Information about camera operations such as zoom, focus, pan, tilt and dollying is significant not only for efficient video coding, but also for content-based video representation. In this paper we describe a high-precision camera operation parameter measurement system and apply it to image motion inferring. First, we outline the implemented system which is designed to provide camera operation parameters with a high precision required for image coding applications. Second, we calibrate the camera lens to determine its exact optical properties, A pin-hole camera model with the 2nd order radial lens distortion and a two-image calibration technique are employed. Finally, we use the pan, tilt and zoom parameters measured by the system to infer image motion. The experimental results show that the inferred motion coincides with the actual motion very closely. Compared to the motion analysis techniques that estimate camera motion from video sequences, our approach does not suffer from ambiguity, thus can provide reliable and accurate image global motion. The obtained motion can be applied to image mosaicing, moving object segmentation, object-based image coding, etc     

使用双波带板径向剪切干涉仪检测非球面透镜

为了实现对光学非球面的低成本在线测量,在比较和分析现有非球面检测技术的基础上,设计并制作了一种小型径向剪切干涉仪用于检测非球面透镜。基于波带板可以聚焦成像的原理,该干涉仪采用不同焦距的双波带板产生径向剪切干涉。波带板由工业缩微矢量图制版技术设计和制作而成,并通过实验验证了该波带板的聚焦精度。采用傅里叶变换条纹相位分析法对干涉条纹进行处理,计算出波相差和波面面形。实验中给出了平面波光束经过一个非球面透镜后的波面面形检测结果和误差分析,使用该技术对标准非球面进行测试,波差峰谷值(P-V)达到了λ/5的精度,均方差(RMS)达到λ/10的精度。结果表明,该干涉仪具有体积小、抗干扰能力强等特点,适用于对小型非球面透镜进行在线检测。     

确定CCD相机标定点个数的方法

针对带有径向畸变的单摄像机针孔成像数学模型,提出了确定标定点个数的方法.利用忽略切向畸变的径向一致约束推出线性方程式,应用最小二乘法求得线性方程式的系数.通过不断增加标定点的个数,得到系数的一系列解;观察系数解的变化是否稳定,从而判断所用标定点个数是否足够.     

Practical vignetting correction method for digital camera with measurement of surface luminance distribution

Vignetting refers to the fall-off pixel intensity from the centre towards the edges of the image. This effect is undesirable in image processing and analysis. In the literature, the most commonly used methods of vignetting correction assume radial characteristic of vignetting. In the case of camera lens systems with non-radial vignetting, such approach leads to insufficient correction. Additionally, the majority of vignetting correction methods need a reference image acquired from a uniformly illuminated scene, what can be difficult to achieve. In this paper, we propose a new method of vignetting correction based on the local parabolic model of non-radial vignetting and compensation of non-uniformity of scene luminance. The new method was tested on camera lens system with non-radial vignetting and non-uniformly illuminated scene. In these conditions, the proposed method gave the best correction results among the tested methods.     

便携式吸波涂料吸波性能测试系统的研究

介绍了一种可以测试实际使用中的吸波涂料的吸波性能的方法.与常用方法相比,本方法具有设备简单、测试快速灵活等优点,适于测试实际使用中吸波涂料的吸波性能.对该方法进行了物理实现,给出并分析了实验结果.     

A new solution for camera calibration and real-time image distortion correction in medical endoscopy-initial technical evaluation

Medical endoscopy is used in a wide variety of diagnostic and surgical procedures. These procedures are renowned for the difficulty of orienting the camera and instruments inside the human body cavities. The small size of the lens causes radial distortion of the image, which hinders the navigation process and leads to errors in depth perception and object morphology. This article presents a complete software-based system to calibrate and correct the radial distortion in clinical endoscopy in real time. Our system can be used with any type of medical endoscopic technology, including oblique-viewing endoscopes and HD image acquisition. The initial camera calibration is performed in an unsupervised manner from a single checkerboard pattern image. For oblique-viewing endoscopes the changes in calibration during operation are handled by a new adaptive camera projection model and an algorithm that infer the rotation of the probe lens using only image information. The workload is distributed across the CPU and GPU through an optimized CPU+GPU hybrid solution. This enables real-time performance, even for HD video inputs. The system is evaluated for different technical aspects, including accuracy of modeling and calibration, overall robustness, and runtime profile. The contributions are highly relevant for applications in computer-aided surgery and image-guided intervention such as improved visualization by image warping, 3-D modeling, and visual SLAM.     

Performance analysis of slotted random access channels for W-CDMAsystems in Nakagami fading channels

We perform a new analysis of the performance of the wideband code-division multiple access (W-CDMA) randomized slotted-offset random access channel (RAC) with Nakagami-m fading and compare it with that of a comparable randomized slotted-ALOHA-based RAC. Previously, it was shown that the W-CDMA RAC is fast, robust and simple to implement (see Esmailzadeh, R. and Gustafsson, M., Proc. 1997 IEEE ICUPC Conf, p.43-7, 1997). However, it was assumed that any random access packet arrival events involving multiple packets from cochannel mobile stations would result in lost packets. Closed-form equations are developed for the collision process of the arriving random access packets in slotted-offset and slotted-ALOHA RACs. An analysis is developed of the signal-to-interference-and-noise ratio of a packet involved in a multipacket DS-CDMA collision with a generalized Nakagami fading channel and diversity reception at the base station. A closed-form equation is developed for the bit error rate and packet throughput of the slotted-offset- and slotted-ALOHA-based RACs. The results of the analysis show that considerable improvement in the RAC performance can be achieved when multiple arrival collisions, on the same timeslot and with the same signature code, are partially resolved. The results also show the RAC's sensitivity to fading severity, packet E_b/N ₀, spreading gain and number of base station receive selection diversity antennas. Compared to the randomized slotted-ALOHA designs, W-CDMA RAC performs as well in light fading conditions and slightly worse in severe fading conditions