基于无人机智能视觉的输电线路全息全景重建

针对当前重建方法不能精确展现输电线路实际情况的问题,提出基于无人机智能视觉的输电线路全息全景重建方法。通过分析输电线路全息全景重建原理,采用无人机智能视觉技术对输电线路进行拍照,对输电线路全息全景图像进行采集和特征提取等预处理,跟踪图像特征,引入立体匹配算法,实现输电线路全息全景的重构。实验结果表明,所提方法输电线路重建精度高,视觉效果与实际相符,更具实用性及可行性。     

Three-dimensional point cloud alignment detecting fiducial markers by structured light stereo imaging

In recent years, various methodologies of shape reconstruction have been proposed with the aim at creating Computer-Aided Design models by digitising physical objects using optical sensors. Generally, the acquisition of 3D geometrical data includes crucial tasks, such as planning scanning strategies and aligning different point clouds by multiple view approaches, which differ for user’s interaction and hardware cost. This paper describes a methodology to automatically measure three-dimensional coordinates of fiducial markers to be used as references to align point clouds obtained by an active stereo vision system based on structured light projection. Intensity-based algorithms and stereo vision principles are combined to detect passive fiducial markers localised in a scene. 3D markers are uniquely recognised on the basis of geometrical similarities. The correlation between fiducial markers and point clouds allows the digital creation of complete object surfaces. The technology has been validated by experimental tests based on nominal benchmarks and reconstructions of target objects with complex shapes.     

基于双目视觉的无人机悬停精度测量研究

为评测悬停状态无人机的稳定性,设计了一套基于双目立体视觉的无人机悬停状态评测系统。首先结合双目相机标定对视频图像校正,并利用提出的邻域灰度改进分级匹配策略,获取匹配特征点;然后根据重建原理计算求得视野中无人机三维坐标数据;最后利用悬停精度测量函数评测无人机的稳定程度。实验证明系统有效匹配目标的特征点,计算出目标三维坐标,同时根据其相对控制精度的浮动,对无人机悬停状态进行评测。     

Probabilistic voxel mapping using an adaptive confidence measure of stereo matching

In this paper, we describe a probabilistic voxel mapping algorithm using an adaptive confidence measure of stereo matching. Most of the 3D mapping algorithms based on stereo matching usually generate a map formed by point cloud. There are many reconstruction errors. The reconstruction errors are due to stereo reconstruction error factors such as calibration errors, stereo matching errors, and triangulation errors. A point cloud map with reconstruction errors cannot accurately represent structures of environments and needs large memory capacity. To solve these problems, we focused on the confidence of stereo matching and probabilistic representation. For evaluation of stereo matching, we propose an adaptive confidence measure that is suitable for outdoor environments. The confidence of stereo matching can be reflected in the probability of restoring structures. For probabilistic representation, we propose a probabilistic voxel mapping algorithm. The proposed probabilistic voxel map is a more reliable representation of environments than the commonly used voxel map that just contains the occupancy information. We test the proposed confidence measure and probabilistic voxel mapping algorithm in outdoor environments.     

大规模室外图像3维重建技术研究进展

基于图像的3维重建旨在从一组2维多视角图像中精确地恢复真实场景的几何形状,是计算机视觉和摄影测量中基础且活跃的研究课题,具有重要的理论研究意义和应用价值,在智慧城市、虚拟旅游、数字遗产保护、数字地图和导航等领域有着广泛应用。随着图像采集系统（智能手机、消费级数码相机和民用无人机等）的普及和互联网的高速发展,通过搜索引擎可以获取大量关于某个室外场景的互联网图像。利用这些图像进行高效鲁棒准确的3维重建,为用户提供真实感知和沉浸式体验已经成为研究热点,引发了学术界和产业界的广泛关注,涌现了多种方法。深度学习的出现为大规模室外图像的3维重建提供了新的契机。首先阐述大规模室外图像3维重建的基本串行过程,包括图像检索、图像特征点匹配、运动恢复结构和多视图立体。然后从传统方法和基于深度学习的方法两个角度,分别系统全面地回顾大规模室外图像3维重建技术在各重建子过程中的发展和应用,总结各子过程中适用于大规模室外场景的数据集和评价指标。最后介绍现有主流的开源和商业3维重建系统以及国内相关产业的发展现状。     

Autonomous Driving with Concurrent Goals and Multiple Vehicles: Experiments and Mobility Components

In this paper, we describe a complete system for mission planning and execution for multiple robots in natural terrain. We report on experiments with a system for autonomously driving two vehicles based on complex mission specifications. We show that the system is able to plan local paths in obstacle fields based on sensor data, to plan and update global paths to goals based on frequent obstacle map updates, and to modify mission execution, e.g., the assignment and ordering of the goals, based on the updated paths to the goals.Two recently developed sensors are used for obstacle detection: a high-speed laser range finder, and a video-rate stereo system. An updated version of a dynamic path planner, D*, is used for on-line computation of routes. A new mission planning and execution-monitoring tool, GRAMMPS, is used for managing the allocation and ordering of goals between vehicles.We report on experiments conducted in an outdoor test site with two HMMWVs. Implementation details and performance analysis, including failure modes, are described based on a series of twelve experiments, each over 1/2 km distance with up to nine goals.The work reported here includes a number of results not previously published, including the use of a real-time stereo machine and a high-performance laser range finder, and the use of the GRAMMPS planning system.     

安阳殷墟博物苑虚拟重建三维系统

使用多媒体、虚拟网络技术对安阳殷墟博物苑及其出土文物、雕塑进行了三维重建,所搭建的系统可用于数字考古以及虚拟探游的三维实现。应用技术主要有大规模场景以及精细物体的三维建模技术,包括基于手工测绘数据、基于三维扫描仪以及基于立体像对的建模技术;虚拟探游技术,包括虚拟人技术以及虚拟动画技术;虚拟多媒体技术,包括虚拟音、视频技术以及虚拟信息自动触发技术。通过网络,用户即可实时对殷墟博物苑进行全方位、360°全视角的三维虚拟探游。     

A Survey of Simple Geometric Primitives Detection Methods for Captured 3D Data

The amount of captured 3D data is continuously increasing, with the democratization of consumer depth cameras, the development of modern multi‐view stereo capture setups and the rise of single‐view 3D capture based on machine learning. The analysis and representation of this ever growing volume of 3D data, often corrupted with acquisition noise and reconstruction artefacts, is a serious challenge at the frontier between computer graphics and computer vision. To that end, segmentation and optimization are crucial analysis components of the shape abstraction process, which can themselves be greatly simplified when performed on lightened geometric formats. In this survey, we review the algorithms which extract simple geometric primitives from raw dense 3D data. After giving an introduction to these techniques, from the acquisition modality to the underlying theoretical concepts, we propose an application‐oriented characterization, designed to help select an appropriate method based on one's application needs and compare recent approaches. We conclude by giving hints for how to evaluate these methods and a set of research challenges to be explored.     

3D reconstruction and classification of natural environments by an autonomous vehicle using multi-baseline stereo

In natural outdoor settings, advanced perception systems and learning strategies are major requirement for an autonomous vehicle to sense and understand the surrounding environment, recognizing artificial and natural structures, topology, vegetation and drivable paths. Stereo vision has been used extensively for this purpose. However, conventional single-baseline stereo does not scale well to different depths of perception. In this paper, a multi-baseline stereo frame is introduced to perform accurate 3D scene reconstruction from near range up to several meters away from the vehicle. A classifier that segments the scene into navigable and non-navigable areas based on 3D data is also described. It incorporates geometric features within an online self-learning framework to model and identify traversable ground, without any a priori assumption on the terrain characteristics. The ground model is automatically retrained during the robot motion, thus ensuring adaptation to environmental changes. The proposed strategy is of general applicability for robot’s perception and it can be implemented using any range sensor. Here, it is demonstrated for stereo-based data acquired by the multi-baseline device. Experimental tests, carried out in a rural environment with an off-road vehicle, are presented. It is shown that the use of a multi-baseline stereo frame allows for accurate reconstruction and scene segmentation at a wide range of visible distances, thus increasing the overall flexibility and reliability of the perception system.     

基于数传电台的无人机监管系统研究

针对无人机监管难的问题,基于数传电台技术,研究了采用无人机端和地面站达成大范围区域覆盖的无人机监管办法,提出了较低成本的基于数传电台作为通信手段的无人机监管系统设计.系统通过无人机端与地面站配合实现了较大区域的覆盖,通过入网、轮询、脱网等机制的设计保障了无人机实时位置的获取,通过不同地理环境的实验,证明了本系统具备相应...     

四旋翼无人机飞行过程孪生仿真研究

为了满足无人机在实际飞行过程中的虚实交互、实时响应和精确控制等要求,以四旋翼无人机的飞行过程作为任务需求,提出基于数字孪生技术的四旋翼无人机飞行过程仿真研究。搭建了四旋翼无人机飞行数字孪生系统架构,分析了数字孪生体仿真数据的流向及其作用,并对四旋翼无人机飞行数字孪生系统的功能和意义进行了介绍。从几何、物理、行为和规则等四个方面融合构建了四旋翼无人机的数字孪生体模型。最后进行了四旋翼无人机巡航过程的案例研究,通过仿真案例中的各项参数分析,考察了虚实无人机之间的交互性,证明了数字孪生体模型的精确性,验证了四旋翼无人机飞行数字孪生系统的可行性。     

A fast interactive reverse-engineering system

A new method of reverse engineering for fast, simple and interactive acquisition and reconstruction of a virtual three-dimensional (3D) model is presented. We propose an active stereo acquisition system, which makes use of two infrared cameras and a wireless active-pen device, supported by a reconstruction method based on subdivision surfaces. In the 3D interactive hand sketching process the user draws and refines the 3D style-curves, which characterize the shape to be constructed, by simply dragging the active-pen device; then the system automatically produces a low-resolution mesh that is naturally refined through subdivision surfaces. Several examples demonstrate the ability of the proposed advanced design methodology to produce complex 3D geometric models by the interactive and iterative process that provides the user with a real-time visual feedback on the ongoing work.     

Non-contact 3D acquisition system based on stereo vision and laser triangulation

This paper proposes a novel contact 3D acquisition system based on stereo vision and laser triangulation. The system is composed by several software modules for data acquisition purposes, data calibration, data processing and data reconstruction of 3D scenes. Different 3D image techniques, such as, polynomial determination, cubic spline interpolation and hierarchical space decomposition were used. To validate this method, a simple laboratory prototype machine was built for the purpose of road profile acquisition, road macro and mega texture characterization. In this paper, only the results and discussion of road profile acquisition are presented.     

Recursive estimation of motion and a scene model with a two-camera system of divergent view

This paper deals with recursive reconstruction of a scene model from unknown motion of a two-camera system capturing the images of the scene. Single camera systems with a relatively small field of view have limited accuracy because of the inherent confusion between translation and rotation. Estimation results from the stereo camera systems are also compromised due to this confusion if the systems require the fields of view to intersect for stereo correspondence. The cameras constituting the two-camera system considered in this paper are arranged so that there is a small intersection of the fields of view. This configuration of divergent view improves the accuracy of the structure and motion estimation because the ambiguity mentioned above decreases due to a large field of view. In this paper, a recursive algorithm is proposed for fast scene model reconstruction using a two-camera system of divergent view. Using inversely inferred stereo correspondences in the intersection of the fields of view is also proposed to remove degeneracy of scale factor determination and to acquire more accurate results from the information redundancy. The results of the experiments with long term real image sequences are presented to demonstrate the feasibility of the proposed system.     

基于地磁模型的两轴航向算法

介绍了一种利用地磁模型把三轴数字磁通门变为两轴数字磁通门的方法,首先介绍了一种最新版本的地球磁场模型;接着分析了三轴数字磁通门的工作原理;最后通过利用地磁模型给出了实现两轴数字磁通门的方法.通过不同地点的实验数据表明,利用地磁模型后,两轴数字磁通门的航向误差满足无人机飞行的系统要求.相对于三轴数字磁通门而言,两轴数字磁通门结构由三维立体变成了二维平面,飞机的活动范围也不受限制,航向误差也满足要求.两轴数字磁通门也符合了无人机小体积、微型化、高精度的系统发展趋势.     

Model-based human shape reconstruction from multiple views

Image-based modelling allows the reconstruction of highly realistic digital models from real-world objects. This paper presents a model-based approach to recover animated models of people from multiple view video images. Two contributions are made, a multiple resolution model-based framework is introduced that combines multiple visual cues in reconstruction. Second, a novel mesh parameterisation is presented to preserve the vertex parameterisation in the model for animation. A prior humanoid surface model is first decomposed into multiple levels of detail and represented as a hierarchical deformable model for image fitting. A novel mesh parameterisation is presented that allows propagation of deformation in the model hierarchy and regularisation of surface deformation to preserve vertex parameterisation and animation structure. The hierarchical model is then used to fuse multiple shape cues from silhouette, stereo and sparse feature data in a coarse-to-fine strategy to recover a model that reproduces the appearance in the images. The framework is compared to physics-based deformable surface fitting at a single resolution, demonstrating an improved reconstruction accuracy against ground-truth data with a reduced model distortion. Results demonstrate realistic modelling of real people with accurate shape and appearance while preserving model structure for use in animation.     

无人机辅助智能电网故障终端数据采集优化策略

随着光伏等各类清洁能源的广泛使用,在移动边缘计算的支撑下,无人机经常被用于户外电网终端设备,特别是运行偏差故障终端的数据采集。然而,待采集的终端运行出现差错、终端数量大幅度增长以及无人机有限的能量和动态的飞行等问题,导致无人机难以快速获得待检测终端的准确位置。基于此,设计一种基于边缘计算的无人机辅助故障终端数据采集优化策略。通过构建基于随机分布的位置误差模型,研究一种无人机飞行轨迹和待采集终端设备的任务传输联合优化策略。联合利用 Bernstein 型不等式、凸优化和隐枚举法,构建高效的两阶段优化求解算法。仿真结果表明所提数据采集策略中无人机可以更加靠近户外的电网故障终端设备,数据采集的时间更长且准确率更高。     

三维重构中数码相机参数标定方法研究

随着数码技术的迅速发展,在许多场合人们已逐渐采用数码相机作为主要的图像采集设备.数码相机的标定被认为是实现三维重构基本而又关键的一步,可以为后继的立体图像匹配与三维重构奠定良好的基础.在介绍数码相机成像理论模型和已知相机内部参数的基础上,提出了一种新的利用直角三点来实现数码相机外部参数标定的方法.与现有的标定方法相比,简化了标定需要的特征点的数量和标定装置的复杂程度.文章最后通过实例说明了利用该标定方法实现三维重构的具体步骤和方法,并且验证了此方法的可行性及标定的精度.     

Flexible calibration of structured-light systems projecting point patterns

Structured-light systems (SLSs) are widely used in active stereo vision to perform 3D modelling of a surface of interest. We propose a flexible method to calibrate SLSs projecting point patterns. The method is flexible in two respects. First, the calibration is independent of the number of points and their spatial distribution inside the pattern. Second, no positioning device is required since the projector geometry is determined in the camera coordinate system based on unknown positions of the calibration board. The projector optical center is estimated together with the 3D rays originating from the projector using a numerical optimization procedure. We study the 3D point reconstruction accuracy for two SLSs involving a laser based projector and a pico-projector, respectively, and for three point patterns. We finally illustrate the potential of our active vision system for a medical endoscopy application where a 3D cartography of the inspected organ (a large field of view surface also including image textures) can be reconstructed from a video acquisition using the laser based SLS.     

Graph cut based panoramic 3D modeling and ground truth comparison with a mobile platform – The Wägele

Efficient and comfortable acquisition of large 3D scenes is an important topic for many current and future applications in the field of robotics, factory and office visualization, 3DTV and cultural heritage.In this paper we present both an omnidirectional stereo vision approach for 3D modeling based on graph cut techniques and also a new mobile 3D model acquisition platform where it is employed. The platform comprises a panoramic camera and a 2D laser range scanner for self localization by scan matching. 3D models are acquired just by moving the platform around and recording images in regular intervals. Additionally, we concurrently build 3D models using two supplementary laser range scanners. This enables the investigation of the stereo algorithm’s quality by comparing it with the laser scanner based 3D model as ground truth. This offers a more objective point of view on the achieved 3D model quality.