摄像机径向畸变校正和内参估计的单图标定方法

提出了一种对摄像机的径向畸变进行校正和内参数估计的单图标定方法.拍摄一幅平面标定模板图像,提出若干条直线,拟合在单参数除法畸变模型下的圆弧参数,从而估计出径向畸变.对径向畸变进行校正后,利用标定模板点与经过校正后的图像点之间的对应关系,估计出单应性矩阵.在假定摄像机主点与畸变中心重合的条件下,线性地计算出摄像机焦距初值.以上述线性方法得到的结果为初值,进行非线性优化,最终得到准确的摄像机参数.超广角鱼眼相机和普通数码相机的实验结果表明,本文提出的算法实现简单、适用性广,结果准确,具有较强的实用性.     

带切向畸变的模型可视化摄像机标定

根椐Tsai两步标定方法,在Matlab中首先运用直接线性变换法(DLlr)对摄像机参数进行估计,然后以线性参数为初始值,运用非线性优化方法对摄像机参数进行优化.并对摄像机参数标定过程中的畸变模型进行分析,主要分析了透镜的径向和切向畸变分量.最后根据标定的摄像机参数,实现了摄像机畸变模型可视化.     

基于共面点的摄像机线性标定法

提出了一种线性求解摄像机内外参数的方法。通过分解参数确定相机主点坐标和纵横比,利用径向平行约束求解大部分的外参数,再引入新的畸变模型线性求解其余内外参数。该法特点是采用共面点标定物,且不需摄像机做任何运动就可以实现全过程的线性标定。既避免了非线性优化的繁琐和不稳定,也解决了其它线性法中部分内参数的标定问题。两套实验结果误差分别为0.3391pixels和0.6004pixels,表明该法具有较高的精度,是一种简单、有效、实用的标定法。     

一种改进的机器人手眼系统标定方法

针对机器人手眼系统标定中空间坐标值参考点获取的困难,提出了一种改进的不需要已知坐标值参考点的机器人手眼系统标定方法.该方法的优点是在摄像机内参数标定中考虑了径向畸变,保证了标定精度.在外参数标定中,根据机器人自身运动特性提出了一种简便求取平移矩阵的方法.     

基于两步法的摄像机标定算法

摄像机标定是机器视觉中的一个重要问题.精确的摄像机标定在涉及定量测量的应用中是非常重要的.摄像机标定的目的是得到摄像机的内部参数和外部参数.通过这些参数我们能够将一个点的三维位置与它的图像平面的坐标相匹配.本文提出了一种基于两步法的摄像机标定方法.第一步,使用基于无畸变的相机模型估计标定参数;第二步,在考虑相机畸变的情况下,对第一步中得到的标定参数通过非线性优化进行迭代优化,并求解畸变系数,包括径向畸变系数和切向畸变系数.用单幅图像即可完成标定,标定过程比两步法更为简洁.实验结果表明,这种算法是简单而有效的.     

3D测量系统中的高精度摄像机标定算法

本文在分析完整的摄像机镜头畸变模型的基础上,提出了一种新的标定算法.该算法包括三个步骤,首先在不考虑镜头畸变的情况下利用标定块上的中间若干个点,采用线性优化方法求出除畸变系数以外的其他外部参数和主要的内部参数;然后固定上述已求得的参数,利用线性优化方法求解畸变系数;最后对所有内部参数和外部参数进行全局非线性优化.最后对本文的标定算法进行了标定实验,实验结果表明,本文算法的标定精度可以达到0.0367 mm,可以满足高精度三维测量及其他应用的要求.     

基于因子分解和光束法平差的摄像机自标定

提出一种基于因子分解和光束法平差的摄像机自标定算法,只需手持定焦摄像机围绕物体拍摄3幅以上图像即可估计出摄像机的内参数以及畸变系数.该方法有3个主要特点:一是由于在因子分解重建过程中采用了所有图像的信息,因此具有很好的鲁棒性;二是由于在完成欧式重构后采用光束法平差对摄像机内参数以及畸变系数进行了非线性优化,因此具有较高...     

锥齿行星齿轮传动相位调谐研究

根据锥齿行星齿轮传动的结构和受力的对称性,采用解析方法研究了啮合相位对振动特性的影响,揭示了中心轮齿数和行星轮个数与中心构件的受力及振动特性之间的关系,归纳出3种典型振动模式:轴向平移-扭转、径向平移-扭摆和受力平衡模式。在轴向平移-扭转振动模式下,中心构件呈现轴向平移和绕该轴的扭转振动;在径向平移-扭摆振动模式下,中心构件呈现沿径向的平移和绕该方向的扭摆振动;在受力平衡模式下,中心构件均不振动。数值计算及文献对比证明了解析预测的正确性及其在减振方面的有效性。     

PMP系统中一种新的相位-高度映射算法

在相位测量轮廓术(PMP)系统中,由光路可逆原理将投影仪当成另一台摄像机看待.研究了空间点在摄像机和投影仪上投影关系,得到投影仪无畸变时PMP系统的相位-高度影射关系;再将它展开成多项式,使参数标定变得方便.进一步研究了投影仪存在镜头畸变时,相位畸变量与相位的关系;最后得到考虑镜头畸变的PMP系统相位-高度映射算法及其多项式表达式.通过计算机仿真表明,在通常的镜头畸变情况下采用4阶多项式表达的新算法最大绝对误差达到士1.0369×10-3 mm,标准偏差达到7.832×10-4 mm.最后在实际系统中进行了验证,实验中虽然由于测量误差的影响,测量标准偏差仍然可以达到0.0425mm.     

基于尺度变化的图像灰度投影算法

为了延拓灰度投影算法计算时间上的优越性能,解决传统投影法无法估计视频序列缩放参数问题,本文提出了一种新的基于尺度变化的灰度投影算法.算法根据缩放下投影矢量的特征,采用对数映射其坐标空间的方法,将矢量缩放参数降维成平移参数估计,再使用一维矢量互相关运算求解偏移量.实验结果表明,算法具有较好的鲁棒性,缩放系数位于0.7＜a＜1.3时,256×256图像块的解算时间为0.031s;参数求取精度＜0.03,能够较好的应用于视频帧序列的实时处理.     

Incorporating lens distortion into the design of undistorted catadioptric omnidirectional cameras

An improved approach for design of the catadioptric omnidirectional camera with horizontal scene undistorted imaging is described. In the proposed approach, the influence of the lens distortion on the imaging quality of the omnidirectional camera is taken into account. We establish a radial distortion model for an image pickup lens and retain some opposite distortion in the mirror to correct the distortion existing in the image pickup lens. A horizontal scene undistorted catadioptric omnidirectional camera is designed with an off-the-shelf TV short focus lens using our approach; the numerical simulation shows that the distortion introduced by the imaging lens is eliminated effectively.     

摄象机参数高精度求解方法

提出了一种新的高精度的摄象机参数的求解方法，文章利用透视变换理论建立了摄象机数学模型，模型中考虑了摄象机镜头的径向畸变和切向畸变，首先利用牛顿－高斯非线性搜索方法求争摄象机畸变系数和一个中间矩阵，然后再从中间矩阵中分离出其它模型参数；     

Stereo calibration of binocular ultra-wide angle long-wave infrared camera based on an equivalent small field of view camera

ABSTRACT

In this paper, a stereo calibration method for binocular ultra-wide angle long-wave infrared camera is proposed on the basis of an equivalent small field of view camera. Extrinsic parameters are calibrated through the corrected images from the left and right cameras. They can be viewed as images taken by a small field of view camera. The calibration procedure consists of three steps: monocular calibration, distortion correction and extrinsic parameters calibration. In order to evaluate the accuracy of the method, stereo vision of the camera is modelled and a 3D reconstruction approach is presented. A series of experiments, including intrinsic parameters, extrinsic parameters and 3D reconstruction, are conducted to validate the proposed method. The results show that the baseline length error decreases to 0.67%, and the relative error for the 3D reconstruction of corners is smaller than 8.11%. In contrast to the common stereo calibration method, it improves calibration accuracy.     

电视摄像机主要参数测试系统设计与实施

在监控和军事等领域应用中,对电视摄像机的主要光电参数的准确标定是非常重要的。本文介绍了一种基于视频信号处理的电视摄像机主要光电参数综合检测装置的设计和实施方案。采用特定的测试目标对摄像机成像,视频图像被高精度数字图像采集卡捕获并将数据传送给计算机,再通过数字图像处理软件自动计算,可实现CCD响应度、灵敏度、信噪比、动态范围和电视分辨力、畸变、对比度等参数的准确测试。     

Accurate calibration with highly distorted images

Camera calibration is a two-step process where first a linear algebraic approximation is followed by a nonlinear minimization. The nonlinear minimization adjusts the pin-hole and lens distortion models to the calibrating data. Since both models are coupled, nonlinear minimization can converge to a local solution easily. Moreover, nonlinear minimization is poorly conditioned since parameters with different effects in the minimization function are calculated simultaneously (some are in pixels, some in world coordinates, and some are lens distortion parameters). A local solution is adapted to parameters, which minimize the function easily, and the remaining parameters are just adapted to this solution. We propose a calibration method where traditional calibration steps are inverted. First, a nonlinear minimization is done, and after, camera parameters are computed in a linear step. Using projective geometry constraints in a nonlinear minimization process, detected point locations in the images are corrected. The pin-hole and lens distortion models are computed separately with corrected point locations. The proposed method avoids the coupling between both models. Also, the condition of nonlinear minimization increases since points coordinates are computed alone.     

Scheimpflug stereocamera for particle image velocimetry in liquid flows

A novel stereocamera has been developed based on the angular-displacement method, wherein the two camera axes are oriented in a nonorthogonal manner toward the object plane. The stereocamera satisfies the Scheimpflug condition such that the image plane, the object plane, and the lens plane are nominally colinear. A unique feature of the stereocamera is the introduction of a liquid prism between the object plane and the recording lens, which significantly reduces the radial distortions that arise when imaging through a thick liquid layer. The design of the camera and its computer optimization with geometric modeling are described. Results indicate that the use of a liquid prism reduces the amount of radial distortion by an order of magnitude. The results have been shown to agree very well with experiments.     

Measurement of shaft diameters by machine vision

A machine vision method for accurately measuring the diameters of cylindrical shafts is presented. Perspective projection and the geometrical features of cylindrical shafts are modeled in order to enable accurate measurement of shaft diameters. Some of the model parameters are determined using a shaft of known diameter. The camera model itself includes radial and tangential distortions terms. Experiments were used to measure the accuracy of the proposed method and the effect of the position of the camera relative to the shaft, as well as other factors.