一种利用平行结构光的3D重构算法

论文提出了一种简便的采用等间距平行结构光的3D重构算法。算法不需要对摄像机进行标定,只需求解参考平面的像到参考平面的单应矩阵和光平面的像到光平面的单应矩阵,利用所求得的单应矩阵便可以从空间物体在结构光照射下的图像求出物体的3D坐标。实验表明算法计算简单、行之有效。     

基于单目视觉几何构建的三维扫描系统

为构建基于单目视觉的快速便捷式三维扫描系统,提出一种高精度的单目视觉几何投影的场景建模方法,并开发一种低成本高精度的三维扫描系统。首先,获取平面标定点的图像坐标,经投影变换将其转换为摄像坐标系下的三维空间位置坐标,分别建立平移台面和底座的三维空间平面方程;其次,通过移动平移台面求取同名标定点的空间坐标,求解平移台面的平移向量,并通过落在平移台面和底座上的激光线条求解激光平面;最后,提取图像中的激光光条中心点并将其变换为物体表面的三维点云数据。实验结果表明,投影变换求得的平面方程误差小于0．2％,扫描结果误差低于0．05mm。     

Circular camera array system for 3‐D displays based on the reconstruction of parallax rays

Abstract— A circular camera system employing an image‐based rendering technique that captures light‐ray data needed for reconstructing three‐dimensional (3‐D) images by using reconstruction of parallax rays from multiple images captured from multiple viewpoints around a real object in order to display a 3‐D image of a real object that can be observed from multiple surrounding viewing points on a 3‐D display is proposed. An interpolation algorithm that is effective in reducing the number of component cameras in the system is also proposed. The interpolation and experimental results which were performed on our previously proposed 3‐D display system based on the reconstruction of parallax rays will be described. When the radius of the proposed circular camera array was 1100 mm, the central angle of the camera array was 40°, and the radius of a real 3‐D object was between 60 and 100 mm, the proposed camera system, consisting of 14 cameras, could obtain sufficient 3‐D light‐ray data to reconstruct 3‐D images on the 3‐D display.     

3D Photography Using Shadows in Dual-Space Geometry

A simple and inexpensive approach for extracting the three-dimensional shape of objects is presented. It is based on weak structured lighting. It requires very little hardware besides the camera: a light source (a desk-lamp or the sun), a stick and a checkerboard. The object, illuminated by the light source, is placed on a stage composed of a ground plane and a back plane; the camera faces the object. The user moves the stick in front of the light source, casting a moving shadow on the scene. The 3D shape of the object is extracted from the spatial and temporal location of the observed shadow. Experimental results are presented on five different scenes (indoor with a desk lamp and outdoor with the sun) demonstrating that the error in reconstructing the surface is less than 0.5% of the size of the object. A mathematical formalism is proposed that simplifies the notation and keep the algebra compact. A real-time implementation of the system is also presented.     

Towards precise real-time 3D difference detection for industrial applications

3D difference detection is the task to verify whether the 3D geometry of a real object exactly corresponds to a 3D model of this object. We present an approach for 3D difference detection with a hand-held depth camera. In contrast to previous approaches, with the presented approach geometric differences can be detected in real-time and from arbitrary viewpoints. The 3D difference detection accuracy is improved by two approaches: first, the precision of the depth camera's pose estimation is improved by coupling the depth camera with a high precision industrial measurement arm. Second, the influence of the depth measurement noise is reduced by integrating a 3D surface reconstruction algorithm. The effects of both enhancements are quantified by a ground-truth based quantitative evaluation, both for a time-of-flight (SwissRanger 4000) and a structured light depth camera (Kinect). With the proposed enhancements, differences of few millimeters can be detected from 1 m measurement distance.     

基于一维移动物体的双目装置自标定

给出了平移运动的一维物体所在平面的虚圆点图像及其对摄像机内参数的约束，和约束方程的数值求解方法，从而获得摄像机的内参数. 进一步通过恢复空间点在摄像机坐标系中的坐标，求解出双目摄像机之间的方位，即摄像机的外参数．对于一维物体的一般刚体运动，给出了把它转化为平移运动的方法．模拟实验和真实图像实验结果表明该方法具有较高的求解精度，同时也有一定的应用价值．     

Monocular SLAM with undelayed initialization for an indoor robot

This paper presents a new feature initialization method for monocular EKF SLAM (Extended Kalman Filter Simultaneous Localization and Mapping) which utilizes a 3D measurement model in the camera frame rather than 2D pixel coordinates in the image plane. The key idea is to regard a camera as a range and bearing sensor, of which the range information contains numerous uncertainties. 2D pixel coordinates of measurement are converted to 3D points in the camera frame with an assumed depth. The element of the measurement noise covariance corresponding to the depth of the feature is set to a very high value. And it is shown that the proposed measurement model has very little linearization error, which can be critical for the EKF performance. Furthermore, this paper proposes an EKF SLAM system that combines odometry, a low-cost gyro, and low frame rate (1–2 Hz) monocular vision. Low frame rate is crucial for reducing the price of the processor. This system combination is cost-effective enough to be commercialized for a real vacuum cleaning application. Simulations and experimental results show the efficacy of the proposed method with computational efficiency in indoor environments.     

三维地形地物融合方法研究与应用

为了提高大比例尺下的三维地形与地物融合效果,提出了一种新的地形地物融合方法。该方法利用三维地物的底面是平面这一特点,在统一坐标框架下,对地形数据进行预处理,消除了影响地形地物融合的高程点,再利用Delauney三角网算法生成TIN模型模拟地形。预处理过程修正了影响融合效果的高程点数据,提高了融合效果,同时减少了原始地形数据的数据量,从而提高了构建TIN模型的效率。结果表明,该方法能较好地实现三维地形地物的融合。     

基于投影仪和摄像机的结构光视觉标定方法

为实现基于投影仪和摄像机的结构光视觉系统连续扫描,需要计算投影仪投影的任意光平面与摄像机图像平面的空间位置关系,进而需要求取摄像机光心与投影仪光心之间的相对位置关系。求取摄像机的内参数,在标定板上选取四个角点作为特征点并利用摄像机内参数求取该四个特征点的外参数,从而知道四个特征点在摄像机坐标系中的坐标。利用投影仪自身参数求解特征点在投影仪坐标系中的坐标,从而计算出摄像机光心与投影仪光心之间的相对位置关系,实现结构光视觉标定。利用标定后的视觉系统,对标定板上的角点距离进行测量,最大相对误差为0.277%,表明该标定算法可以应用于基于投影仪和摄像机的结构光视觉系统。     

基于物体特征有效提取和离散点三维重建的3D扫描系统原型研究

针对3D扫描技术的近期发展情况,以及市场关于被摄物体特征有效提取的迫切需求,通过系统的对照相机和投影仪测量的方法与计算,利用离散点三维重建算法、标准化算法详细分析了,作为3D扫描原型系统的关键技术,并深入的对三维坐标重复演算的过程,进行了实践研究与计算,论证了基于投影光编码技术的3D扫描仪原型系统,在物体特征有效提取和离散点三维重建中完全可以高效应用;同时,使用焦距标准化运算、逆向倾角变形运算、逆向扭曲变形运算三种方法,综合论述了物体特征有效提取和离散点三维重建过程的相关内容,测试了原型系统对真实文物的扫描情况,展开了该原型系统可应用于不同材料,不同种类物体的扫描,并能有效的进行数字化物体特征识别的研究结论。     

单像机有源形状恢复方法研究

物体表面三维形状恢复是计算机视觉的一个重要研究内容.给出了一种利用网格结 构光,采用单像机恢复物体表面三维形状的方法.提出了一种新的定标方法和投影模板检测 算法,并构造完成了有源三维重建实验系统.结果表明该方法能快速、准确地恢复物体形状.     

A theoretical 2D image model for locating 3D targets

To construct a water quality monitoring system, challenging issues need to be addressed regarding the acquisition of target information (e.g. 3D location and occlusion) as well as the behavioural analysis of aquatic organisms. This paper presents a novel 3D information acquisition and location method, by means of an information acquisition platform consisting of a monitoring terminal, frame grabbers, a single camera and a single mirror. Using this platform, we propose a theoretical 2D image model for locating 3D targets and then validate it using data obtained from both real and artificial fish. The proposed model is based on the principles of light refraction, plane mirror imaging, underwater objects and camera imaging as well as the technologies of digital to analog conversion and object segmentation. In contrast with existing methods, our method can accurately reflect 3D information of aquatic organisms, thus providing critical technical support for the development of water quality monitoring systems in the future.     

利用OpenGL实现三维物体测量数据的可视化

本文运用计算机视觉测量技术,将结构光法测得的反映物体轮廓形状的二维图像信息进行三维重构。充分利用OpenGL三维图形构造和渲染等功能,借助Visual C 6.0开发了一套三维物体重构系统,实现了三维物体测量数据的快速可视化。     

Research on Application of Location Technology in 3D Virtual Environment Modeling System for Substation Switch Indicator

Substation inspection work plays a very important role in ensuring the normal production and the safe operation of a transformer substation. Use of a substation inspection robot can effectively solve the omission problems of a manual inspection. It can further improve the unmanned and automation of substation and improve security of station. A substation inspection system requires the establishment of a spatial position relation between the robot and the inspection object in the monitoring station. Key technology is the spatial location of the object being detected in the substation. The position of inspection object is unknown. This paper gives technical route of monocular vision positioning system based on switch indicator sign cooperative target. The knife switch indicator is one of the most important objects in the substation inspection. Usually the switch indicator lies in the middle or top of the substation equipment and conventional method can’t measure. This paper presents a substation label measurement method based on monocular vision. In this method, the label frame of knife switch indicator is as a cooperative target. The 3D coordinates and attitude of the label frame can be calculated in a camera coordinates system. At the same time, this paper introduces an extraction process of knife brake indicator label with multi-features under complex background. At last, we do simulation experiment for positioning technology of 3D virtual environment modeling system for substation switch indicator. Simulation results show that the method introduced in this paper can realize positioning of substation switch indicator label.     

双目视觉下人体运动的三维模型描述方法研究

提出一种在双目视觉的条件下,利用光流金字塔跟踪算法跟踪关节点,以解决传统光流不能进行大幅度运动跟踪的问题,并利用极线约束进行三维重建获得深度信息,结合对消失关节点的位置预测求出相应的三维坐标,再利用层次化的描述方法将三维坐标转化为三维模型中各个关节点的旋转角度,实现对人体运动的模型描述。实验结果表明,该算法能有效地对人体的运动进行描述。     

基于单视频图像序列的人体三维姿态重建

提出了至少存在一个深度值已知点的约束条件下,基于单视频图像序列重建人体三维姿态的方法.利用已知间距的平面点阵来标定获得摄像机参数,在透视投影模型下,根据单视频图像序列中人体关节点的二维数据,重建其三维信息.并将人体运动序列按照运动突变点划分为若干子序列,有效消除了二义性的干扰,较为精确的实现了人体三维姿态的重建.给出了该方法的实验过程及计算结果,验证了该算法的可行性和精度.     

基于医学图像的三维测量技术研究和实现

针对由序列断层医学图像重建得到的三维图形,提出一种交互式三维测量技术.首先通过光线投射法实现了对三维空间中任意一点的拾取,将用户指定的屏幕二维坐标点转化为立体坐标系下的空间三维坐标.选取空间中两点后即可以对三维重建后的病人器官进行测量,得到较为满意的结果.此外,在原有拾取方法的基础上,作出一定改进,使用户更方便地获取空间中任意一点的坐标.     

基于侧影轮廓的图像三维重建方法

针对自标定单幅图像的三维重建问题,提出一种基于侧影轮廓的图像三维重建方法。使用成角度平面镜装置拍摄目标物体,对所得图像进行边缘跟踪,得到闭合的轮廓曲线,利用满足平面镜成像原理的2对侧影轮廓计算灭点,根据灭点间的约束关系计算相机参数,在此基础上重建得到物体的三维模型。实验结果表明,该方法能快速重建逼真的三维模型。     

三维立体视觉机械臂智能抓取分类系统的开发

采用工业相机、工业投影机、普通摄像头、计算机和机械臂开发了一套具有三维立体视觉的机械臂智能抓取分类系统。该系统采用自编软件实现了对工业相机、工业投影机的自动控制和同步，通过前期研究提出的双波长条纹投影三维形貌测量法获取了物体的高度信息，结合opencv技术和普通摄像头获取的物体二维平行面信息，实现了物体的自动识别和分类；利用串口通信协议，将上述处理后的数据传送至机械臂，系统进行几何姿态解算，实现了智能抓取，并能根据抓手上压力反馈自动调节抓手张合程度，实现自适应抓取。经实验证明该系统能通过自带的快速三维形貌获取装置实现准确、快速的抓取工作范围内的任意形状的物体并实现智能分类。     

低成本个性化制造原型系统关键技术

传统制造业一般基于大规模生产方式,个性化产品生产成本较高。利用低成本三维扫描、三维打印技术,提出一套低成本的个性化制造原型系统。该系统首先利用深度相机采集个性化几何数据、对数据去噪配准、生成较高质量的重建网格;上传用户信息,进行个性化产品在线设计;最后利用家用三维打印设备或在线三维打印服务进行制作。为了验证提出的方案,实现了眼镜架个性化设计与制造原型系统。