3D靶标的摄像机三步标定算法与实现

摄像机标定是计算机视觉中的一个必不可少的重要环节,其标定精度影响着三维重建结果的精度。利用摄像机对一个三维正交的棋盘格拍摄一幅有效靶标图像,提取角点,第一步通过透视变换矩阵算法线性求解各内外参数;第二步引入径向和切向畸变,将第一步求得的内外参数作为初始值,求得畸变系数的解;第三步对内参数进行线性优化,得到更为精确的内参数值;最后求解反投影后图像坐标的绝对误差。实验结果表明,该方法具有较高的精度,且简单有效。     

基于微观图像的加工表面3维形貌重建算法研究

切削加工表面由于微观不平度及镜面效应的存在,使得照射其上的光线具有多次散射及后向散射的特性,从而影响了以工件表面图像3维重建形貌的精度。提出了一种基于二向反射分布函数的表面重建算法,构造了以Hapke模型表达的金属切削表面重建方程。该算法以重建方程离散化为手段,计算出光源和物体的倾角和偏角,得到光源和物体的梯度值,最后采用全微分方程对物体表面高度进行恢复。通过对实际切削加工表面图像3维形貌重建结果与触针式测量结果的对比表明,重建形貌粗糙度轮廓贴近实测粗糙度轮廓,证明了本文算法的准确、有效性,为加工表面3维形貌的重建提供了新的思路和方法。     

嵌入式机器视觉实时定位与测量的方法

本文提出了一种嵌入式机器视觉实时定位与测量相结合的测控方法。根据视觉测控系统中的定位与测量问题,利用点集、Hough变换和最小二乘等方法,解决了图像处理理论算法运算量大、工业检测实时性与准确性低等问题。测试结果表明,该方法检测工件的准确性高(基于公差),检测时间≤2.0ms/次。     

Forming processes control by means of artificial intelligence techniques

Forming processes are manufacturing processes that use force and pressure in order to modify the shape of a material part until obtaining the final product. The wide range of non-linear factors that drive this sort of processes make them very complex and extremely difficult to be controlled. Traditional control techniques, like PID controllers, have not offered a reliable solution when global control has been pursued and the figure of the operator still remains present in most of the forming facilities. On the other hand, although operators have demonstrated to be a very successful strategy when controlling this type of processes, the actual market evolution towards the fabrication of more complex parts, made of lower formability materials at higher production rates, is decreasing their capacity of reaction when solving the daily problems. Thus, the development of new global control systems based not on traditional control techniques and mathematical models but on the control strategy that has been used successfully for many years, the control through the experience and knowledge is now even more necessary. In the present work, an intelligent control system based on one of the main techniques within the artificial intelligence, expert systems, has been developed. The main purpose of this intelligent control system is to emulate the decisions that expert operators take but in a quicker and more reliable way. The developed intelligent control system has been installed in a blanking facility and very good results have been achieved.     

VICUR: A human-vision-based algorithm for curve reconstruction

In this paper, a new algorithm, named VICUR, is presented for curve reconstruction problem. From a set of unorganized points, the proposed algorithm can construct curves that look natural to human vision. The VICUR algorithm is based on two connectivity criteria: proximity and good continuation from the prominent Gestalt principles of perception. Experimental results are presented to show the effectiveness of VICUR.     

Detailed Real-Time Urban 3D Reconstruction from Video

The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered coordinates. It is designed using current state of the art real-time modules for all processing steps. It employs commodity graphics hardware and standard CPU’s to achieve real-time performance. We present the main considerations in designing the system and the steps of the processing pipeline. Our system extends existing algorithms to meet the robustness and variability necessary to operate out of the lab. To account for the large dynamic range of outdoor videos the processing pipeline estimates global camera gain changes in the feature tracking stage and efficiently compensates for these in stereo estimation without impacting the real-time performance. The required accuracy for many applications is achieved with a two-step stereo reconstruction process exploiting the redundancy across frames. We show results on real video sequences comprising hundreds of thousands of frames.     

RoadCompass: following rural roads with vision + ladar using vanishing point tracking

We present a vision- and ladar-based approach to autonomous driving on rural and desert roads that has been tested extensively in a closed-loop system. The vision component uses Gabor wavelet filters for texture analysis to find ruts and tracks from which the road vanishing point can be inferred via Hough-style voting, yielding a direction estimate for steering control. The ladar component projects detected obstacles along the road direction onto the plane of the front of the vehicle and tracks the 1-D obstacle “gap” presumed due to the road to yield a lateral offset estimate. Several image- and state-based tests to detect failure conditions such as off-road poses (i.e., there is no road to follow) and poor lighting due to sun glare or distracting shadows are also explained. The system’s efficacy is demonstrated with analysis of diverse logged data including from the 2005 DARPA Grand Challenge, as well as tests with full control of a vehicle over 15 km of difficult roads at up to 37 km/h with no waypoints.

基于主动视觉和超声的机器人目标跟踪系统

运动目标跟踪技术是未知环境下移动机器人研究领域的一个重要研究方向。该文提出了一种基于主动视觉和超声信息的移动机器人运动目标跟踪设计方法,利用一台SONY EV-D31彩色摄像机、自主研制的摄像机控制模块、图像采集与处理单元等构建了主动视觉系统。移动机器人采用了基于行为的分布式控制体系结构,利用主动视觉锁定运动目标,通过超声系统感知外部环境信息,能在未知的、动态的、非结构化复杂环境中可靠地跟踪运动目标。实验表明机器人具有较高的鲁棒性,运动目标跟踪系统运行可靠。     

基于模型的单视图线性共面四点算法

通过利用三维点的仿射坐标对于刚体变换而言是不变的,并且对计算机坐标系到图像坐标系的坐标变换而言也是不变的这一特性,开发了从一个目标单视图线性复原其三维位姿的新算法,该算法只需4个特征点即可精确实现目标的三维位姿的线性重建。实验表明,该算法快速高效,误差性能良好,抗噪能力较强。     

基于计算机视觉的虚实场景合成方法研究

开发了一种虚拟场景与实时视频之间的合成技术,提出了一种新的基于非定标技术的虚实配准方法,有效地解决了基于标识的三雏注册系统要求摄像机内参在系统运行过程中不能发生改变的限制.详细介绍了系统所采用的基于计算机视觉的标识识别和实时自动摄像机位置、姿态跟踪算法,并给出了系统运行结果,成功地将该技术应用于虚拟规划系统中.