一般平面机器人的工作空间分析

本文讨论一般的旋转关节平面机器人的工作空间问题，给出了作为工作空间的圆环区域的内、外半径有圆环自身的半径（厚度），同时对文献「５」的示便中关于平面机器人工作范围的一个结论进行了分析。     

基于OSG与Qt的FAST三维场景仿真

为解决FAST基地可视化的问题,开发了一套基于OpenSceneGraph(OSG)与Qt的三维场景仿真系统。通过三维建模,计算机程序自动化布局,OSG虚拟场景搭建等,将FAST的场景进行仿真显示。通过数据驱动实现对虚拟场景的实时更新,同时采用OSG的粒子系统来模拟雨雪天气特效场景。该系统将FAST的场景实时显现在技术工作人员面前,具有场景漫游,动态演示等基本人机交互功能,可为FAST基地的实践工作提供辅助决策依据。     

Visual command of a robot using 3D-scene reconstruction in an augmented reality system

This paper presents an augmented reality system that has been developed to reconstruct 3D scenes from a single camera's view. The camera is supposed to be calibrated in the world frame of reference. The 3D-model is known and correctly matched to its 2D-image. A 3D-object pose recovery algorithm that combines three methods to reach a better robustness and accuracy has been developed. A comparison between these methods is given, as well as a discussion about their advantages and drawbacks. Some experimental results on real images that demonstrate the robustness and the accuracy of the proposed system are presented as well as the visual command of a robot based upon the reconstructed scene.     

VECW:一个虚拟环境的构造和漫游系统

如何真实地在计算机中表达现实世界是计算机图形学的一个重要研究方向。基于几何造型的图像绘制混合是一种很有应用前景的方法。文中在实现前人提出的从建筑物照片中提取建筑物的几模型和相应纹理映射的算法的基础上,给出了一个虚拟环境的构造和漫游系统,简称ＶＥＣＷ。     

激光雷达惯导耦合的里程计与建图方法

针对现有的激光里程计方法在室外动态道路场景中存在里程计精度较低、鲁棒性不足的问题,提出一种3D激光雷达和MEMS惯导耦合的里程计与建图方案.在不同的线程上依次执行数据预处理、顾及动态障碍物的特征提取、激光里程计和激光建图模块.利用KITTI数据和实测数据,对改进方案与目前流行的LOAM、Lego-LOAM方案进行定性和定量的激光里程计精度评定.测试结果表明,改进方案在满足系统实时性的要求下,激光里程计精度优于LOAM方案,与Lego-LOAM方案性能相当.     

虚拟环境中大范围三维地形模型简化方法研究与实现

大范围三维地形模型生成技术是虚拟自然环境和虚拟仿真领域中视景系统的重要组成部分,本文基于真实地形数据的地形生成及实时显示技术,分别介绍了常用的地形简化方法视截体裁剪技术、细节层次模型(LOD)技术和多分辨率纹理贴图(mip-map纹理)技术,并提出了一种基于视点变化的地形模型简化方法——基于视点自动裁剪的多LOD模型生成技术。     

基于二维激光雷达的自动室内三维重建系统

设计了一个基于二维激光雷达的自动室内三维重建系统.系统的硬件由一套自行设计的基于2D激光雷达的三维扫描系统和一台电脑构成.介绍了系统的软件模块,提出了结合最近点迭代(ICP)和通用多边形裁剪(GPC)的3D平面场景合成方法.ICP能够获得不同采集位置之间的位置变化,以此能将各个不同位置获得的3D场景转换到同一坐标系下.场景合成时的碎平面问题通过GPC方法来解决.实验结果表明:该系统成本低,精度高,能稳定可靠地实现室内场景的自动三维重建.     

A quasi-dense approach to surface reconstruction from uncalibrated images

This paper proposes a quasi-dense approach to 3D surface model acquisition from uncalibrated images. First, correspondence information and geometry are computed based on new quasi-dense point features that are resampled subpixel points from a disparity map. The quasi-dense approach gives more robust and accurate geometry estimations than the standard sparse approach. The robustness is measured as the success rate of full automatic geometry estimation with all involved parameters fixed. The accuracy is measured by a fast gauge-free uncertainty estimation algorithm. The quasi-dense approach also works for more largely separated images than the sparse approach, therefore, it requires fewer images for modeling. More importantly, the quasi-dense approach delivers a high density of reconstructed 3D points on which a surface representation can be reconstructed. This fills the gap of insufficiency of the sparse approach for surface reconstruction, essential for modeling and visualization applications. Second, surface reconstruction methods from the given quasi-dense geometry are also developed. The algorithm optimizes new unified functionals integrating both 3D quasi-dense points and 2D image information, including silhouettes. Combining both 3D data and 2D images is more robust than the existing methods using only 2D information or only 3D data. An efficient bounded regularization method is proposed to implement the surface evolution by level-set methods. Its properties are discussed and proven for some cases. As a whole, a complete automatic and practical system of 3D modeling from raw images captured by hand-held cameras to surface representation is proposed. Extensive experiments demonstrate the superior performance of the quasi-dense approach with respect to the standard sparse approach in robustness, accuracy, and applicability.     

GIS数据融合的虚拟现实系统探讨

针对现有三维GIS系统以及虚拟现实系统存在的问题,基于可动态更新GIS数据开发了具备三维场景漫游、外部数据库查询和部分空间分析功能的虚拟现实系统。该文首先介绍了地理信息系统和虚拟现实的现状及其融合发展的背景,然后描述了在Visual VC＋＋．NET开发环境及OpenGL函数库的基础上,利用Terra Vista、MuhiGen Creator及Vega等仿真建模、实时渲染工具建造系统的过程,并以“数字都江堰演示系统”的建设证实了其实用效果。     

An active trinocular vision system of sensing indoor navigation environment for mobile robots

Intelligent autonomous mobile robots must be able to sense and recognize 3D indoor space where they live or work. However, robots are frequently situated in cluttered environments with various objects hard to be robustly perceived. Although the monocular and binocular vision sensors have been widely used for mobile robots, they suffer from image intensity variations, insufficient feature information and correspondence problems. In this paper, we propose a new 3D sensing system, in which the laser-structured-lighting method is basically utilized because of the robustness on the nature of the navigation environment and the easy extraction of feature information of interest. The proposed active trinocular vision system is composed of the flexible multi-stripe laser projector and two cameras arranged with a triangular shape. By modeling the laser projector as a virtual camera and using the trinocular epipolar constraints, the matching pairs of line features observed into two real camera images are established, and 3D information from one-shot image can be extracted on the patterned scene. For robust feature matching, here we propose a new correspondence matching technique based on line grouping and probabilistic voting. Finally, a series of experimental tests is performed to show the simplicity, efficiency, and accuracy of this proposed sensor system for 3D environment sensing and recognition.     

基于自适应核密度估计的运动目标检测

在计算机视频监控系统中,主要的目的是在摄像机固定的视频图像中检测出运动目标,在诸多检测方法中最常用的是减背景技术。减背景技术的关键是背景建模,噪声的干扰、检测方法的自适应性、模型的正确性等问题都是在背景建模过程中必须解决的问题。为了提高建模精度,本文提出了一个非参数化建模技术,称为自适应核密度估计,具有较好的适应性和鲁棒性。它是一种基于场景中像素的概率密度函数来构建的非参数核密度估计的统计模型。     

Automatic 3D Indoor Scene Updating with RGBD Cameras

Since indoor scenes are frequently changed in daily life, such as re‐layout of furniture, the 3D reconstructions for them should be flexible and easy to update. We present an automatic 3D scene update algorithm to indoor scenes by capturing scene variation with RGBD cameras. We assume an initial scene has been reconstructed in advance in manual or other semi‐automatic way before the change, and automatically update the reconstruction according to the newly captured RGBD images of the real scene update. It starts with an automatic segmentation process without manual interaction, which benefits from accurate labeling training from the initial 3D scene. After the segmentation, objects captured by RGBD camera are extracted to form a local updated scene. We formulate an optimization problem to compare to the initial scene to locate moved objects. The moved objects are then integrated with static objects in the initial scene to generate a new 3D scene. We demonstrate the efficiency and robustness of our approach by updating the 3D scene of several real‐world scenes.     

目标三维场景建模与实时红外仿真技术研究

针对景象匹配系统对红外图像实时性的要求越来越高的特点,提出了基于目标三维场景的实时红外仿真方法。首先,设计了红外场景仿真的总体方案;其次,对材质红外图像计算、红外图像数据库建立、基于全球三维场景的实时红外场景建模三个关键技术做了初步实现;最后,结合红外场景仿真方案完成了系统。实验结果表明：该方法生成的红外图像与实拍红外图像的变化规律基本一致,从而为实时制备红外基准图提供了一种有效途径。     

基于动态分级的自适应运动目标处理SLAM算法

针对移动机器人在动态环境中视觉同时定位和地图构建（visual simultaneous localization and mapping,VSLAM）精度低、鲁棒性差的问题,提出了一种自适应运动目标处理SLAM算法（adaptive dynamic SLAM,AD-SLAM）。基于对极几何约束的场景动态分级前端实时感知运行环境的动态变化。通过基于几何约束和运动概率的低动态环境动态特征和基于语义分割的高动态环境动态目标处理消除运动目标。在计算机视觉数据集TUM上进行实验验证,结果表明提出方案在复杂动态环境中保证算法实时性的前提下提升了移动机器人建图过程中定位的精度和鲁棒性。     

Grasp programming by demonstration in virtual reality with automatic environment reconstruction

A virtual reality system enabling high-level programming of robot grasps is described. The system is designed to support programming by demonstration (PbD), an approach aimed at simplifying robot programming and empowering even unexperienced users with the ability to easily transfer knowledge to a robotic system. Programming robot grasps from human demonstrations requires an analysis phase, comprising learning and classification of human grasps, as well as a synthesis phase, where an appropriate human-demonstrated grasp is imitated and adapted to a specific robotic device and object to be grasped. The virtual reality system described in this paper supports both phases, thereby enabling end-to-end imitation-based programming of robot grasps. Moreover, as in the PbD approach robot environment interactions are no longer explicitly programmed, the system includes a method for automatic environment reconstruction that relieves the designer from manually editing the pose of the objects in the scene and enables intelligent manipulation. A workspace modeling technique based on monocular vision and computation of edge-face graphs is proposed. The modeling algorithm works in real time and supports registration of multiple views. Object recognition and workspace reconstruction features, along with grasp analysis and synthesis, have been tested in simulated tasks involving 3D user interaction and programming of assembly operations. Experiments reported in the paper assess the capabilities of the three main components of the system: the grasp recognizer, the vision-based environment modeling system, and the grasp synthesizer.     

HVS：一种基于实景图象的虚拟现实系统

大多数的虚拟现实比试在于计算机图形技术,先由多边形构造虚拟场景的三维几何模型,再由计算机根据用户的观察点和观察方向实时绘制出用户所看到的虚拟场景,ＨＶＳ 另一种思路,由计算机自动拉接、变形与组织许多幅度散的实景图象或连续视频,生成虚拟场景,这种虚拟场人有照片质量的视觉效果,被我们称为虚拟实景空间,虚拟实时空间能为用户提供、后退、仰视、俯视、３６０度环境、近看、远看等漫游能力,运行它不需要高性能的图     

虚拟现实建模技术在数字化发射场中的应用

建立数字化发射场是卫星发射信息化和应急保障的基础。本文结合某卫星发射场实时性和交互性视景仿真实现的特点,采用基于三维几何模型的建模及动态显示技术的虚拟场景创建方法,讨论了虚拟漫游系统中建模流程、方法,以及关键技术的实现,分析了通用的三维场景建模的技术路线和流程,给出了地物、天空和实体模型构建的实际解决方案、方法,讨论了基于MultiGen Creator的模型格式转换、纹理贴图、模型简化、LOD技术、DOF技术等建模关键技术。采用MultiGen Creator和Vega软件平台,开发出了一个桌面型的虚拟发射场仿真系统,实现了发射场的数字化和卫星发射的实时仿真。     

复杂地形下无人机倾斜摄影技术的校园三维实景建模

针对无人机倾斜摄影技术在复杂地形条件下三维实景建模的可行性及其精度是否满足实际大比例尺测量要求的问题,本文以福州市马尾区阳光学院校园为例,采用大疆经纬系列无人机搭载云眼系列五镜头相机的方式完成测区倾斜影像数据的采集.采用实时动态(Real-Time Kinematic,RTK)连接千寻CORS账号的量测方式完成测区控制...     

基于NT的海战场三维地形的生成与实时显示

海战场环境仿真是海军作战模拟的重要内容,逼真的战场环境实时仿真是作战模拟的基础,它为保障、分析、作战评估等试验提供了仿真平台。针对海战场仿真中大规模三维地形的生成与实时显示问题,提出了一种基于VEGA和NT平台的解决方案,讨论了DEM数据的组织及分割、数据格式的转换以生成OpenFlight格式的地形数据,介绍如何把地形数据加入VEGA场景中重新拼接,设置视点参数,最后转换为Fret格式实现实时显示。     

Human behavior clustering for anomaly detection

This paper aims to address the problem of modeling human behavior patterns captured in surveillance videos for the application of online normal behavior recognition and anomaly detection. A novel framework is developed for automatic behavior modeling and online anomaly detection without the need for manual labeling of the training data set. The framework consists of the following key components. 1) A compact and effective behavior representation method is developed based on spatial-temporal interest point detection. 2) The natural grouping of behavior patterns is determined through a novel clustering algorithm, topic hidden Markov model (THMM) built upon the existing hidden Markov model (HMM) and latent Dirichlet allocation (LDA), which overcomes the current limitations in accuracy, robustness, and computational efficiency. The new model is a four-level hierarchical Bayesian model, in which each video is modeled as a Markov chain of behavior patterns where each behavior pattern is a distribution over some segments of the video. Each of these segments in the video can be modeled as a mixture of actions where each action is a distribution over spatial-temporal words. 3) An online anomaly measure is introduced to detect abnormal behavior, whereas normal behavior is recognized by runtime accumulative visual evidence using the likelihood ratio test (LRT) method. Experimental results demonstrate the effectiveness and robustness of our approach using noisy and sparse data sets collected from a real surveillance scenario.