Using roadmaps to classify regions of space for autonomous robot navigation

The roadmap approach to robot path planning is one of the earliest methods. Since then, many different algorithms for building roadmaps have been proposed and widely implemented in mobile robots but their use has always been limited to planning in static, totally known environments. In this paper we combine the use of dynamic analogical representations of the environment with an efficient roadmap extraction method, to guide the robot navigation and to classify the different regions of space in which the robot moves. The paper presents the general reference architecture for the robotic system and then focuses on the algorithms for the construction of the roadmap, the classification of the regions of space and their use in robot navigation. Experimental results indicate the applicability and robustness of this approach in real situations.     

3D environmental extremum seeking navigation of a nonholonomic mobile robot

A nonholonomic under-actuated robot with bounded control travels in a 3D region. A single sensor provides the value of an unknown scalar field at the current location of the robot. We present a new kinematic control paradigm to drive the robot to the maximizer of the field, which is different from conventionally trying to align the velocity vector with the field gradient. The proposed strategy does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous analysis and justification are provided. Simulation results confirm the applicability and performance of the proposed guidance approach.     

移动导航系统数字地图路网数据的描述与组织

导航电子地图路网数据的描述,组织和管理是移动导航系统的设计中涉及的关键问题。从移动导航系统对路网数据的信息要求出发,针对以往路网数据模型的不足,探讨了一种名为HOT的层次化路网模型。详细论述了该模型的数据对象描述和层次结构定义,特别是针对网络拓扑结构的刻画给出了解决方案。通过在某市交通信息网格项目中的应用,表明该模型具有信息完备、结构清晰、简洁实用等优点。     

面向三维导航的智能终端传感器数据处理技术

针对智能终端传感器在三维场景导航交互中不稳定问题,提出了一种基于可变平滑归一化模型的传感器数据处理算法.根据传感器数据特点和不同滑动平滑模型数据处理的特性,将不同平滑模型进行组合,并实现平滑窗口可变;同时,运用归一化算法,对数据进行等距处理.在基于终端的三维导航交互系统的实验结果表明,所提算法对传感器低频数据处理后,数据标准方差减小了71.3%,明显地减少了数据扰动;对高频数据处理后,数据标准方差减小了7.9%,有效地保留了信号特征.所提方法能够提高智能终端在三维导航交互中的稳定性和连续性.     

基于大数据聚类的工业遥操作机器人位姿定位控制系统设计

针对工业遥操作机器人位姿定位过程中难以同步控制位置和姿态角,导致位姿定位准确性较差的问题,利用大数据聚类技术,从硬件和软件两个方面优化设计工业遥操作机器人位姿定位控制系统。通过位姿传感器的改装,保证传感器设备能够同时测量机器人位置与姿态,改装定位控制器和驱动器。在系统硬件的支持下,考虑机器人组成结构、运动原理和动力学理论,构建机器人数学模型,在该模型下模拟机器人遥操作过程,确定机器人位姿的定位控制目标。实时采集机器人位姿数据,利用大数据聚类技术计算定位控制量,在控制器的约束下,实现系统的位姿定位控制功能。通过系统测试实验得出结论：综合多种类型的运动情况,在优化设计系统的控制下,机器人的位置误差平均值为4.5mm,姿态角控制误差为0.04°。     

Geometrical recovery of missing data for shape from motion

This paper studies the geometrical recovery of an incomplete observation matrix for converting existing 2D video sequences to 3D content. In situations when converting previously recorded monoscopic video to 3D, several entries of the observation matrix have not been observed and other entries have been perturbed by the influence of noise. In such cases, there is no simple solution for SVD factorization for shape from motion. In this paper, a new recovery algorithm is proposed for recovering missing feature points, by minimizing the influence of noise, using iteratively geometrical correlations between a 2D observation matrix and 3D shape. Results in practical situations demonstrated with synthetic and real video sequences verify the efficiency and flexibility of the proposed method.     

Element-Partition-Based Methods for Visualization of 3D Unstructured Grid Data

Element-partition-based methods for visualization of 3D unstructured grid data are presented.First,partition schemes for common elements,including curvilinear tetrahedra,pentahedra,hexahedra,etc.,are given,so that complex elements can be divided into several rectilinear tetrahedra,and the visualization processes can be simplified.Then,a slice method for cloud map and an iso-surface method based on the partition schemes are described.     

3D geometry reconstruction from orthographic views: A method based on 3D image processing and data fitting

Industrial esthetic designers typically produce hand-drawn sketches in the form of orthographic projections. A subsequent translation from 2D-drawings to 3D-models is usually necessary. This involves a considerably time consuming process, so that some automation is advisable.     

Touching annotations: A visual metaphor for navigation of annotation in digital documents

Direct touch manipulation interactions with technology are now commonplace and significant interest is building around their use in the culture and heritage domain. Such interactions can give people the opportunity to explore materials and artefacts in ways that would otherwise be unavailable. These are often heavily annotated and can be linked to a large array of related digital content, thus enriching the experience for the user. Research has addressed issues of how to present digital documents and their related annotations but at present it is unclear what the optimal interaction approach to navigating these annotations in a touch display context might be.In this paper we investigate the role of two alternative approaches to support the navigation of annotations in digitised documents in the context of a touch interface. Through a control study we demonstrate that, whilst the navigation paradigm displays a significant interaction with the type of annotations task performed, there is no discernible advantage of using a natural visual metaphor for annotation in this context. This suggests that design of digital document annotation navigation tools should account for the context and navigation tasks being considered.     

Gesture recognition using Bezier curves for visualization navigation from registered 3-D data

This paper presents a gesture recognition system for visualization navigation. Scientists are interested in developing interactive settings for exploring large data sets in an intuitive environment. The input consists of registered 3-D data. A geometric method using Bezier curves is used for the trajectory analysis and classification of gestures. The hand gesture speed is incorporated into the algorithm to enable correct recognition from trajectories with variations in hand speed. The method is robust and reliable: correct hand identification rate is 99.9% (from 1641 frames), modes of hand movements are correct 95.6% of the time, recognition rate (given the right mode) is 97.9%. An application to gesture-controlled visualization of 3D bioinformatics data is also presented.     

Automated reconstruction of 3D input data for noise simulation

Noise is one of the main problems in urban areas. To monitor and manage noise problems, governmental organisations at all levels are obliged to regularly carry out noise studies. The simulation of noise is an important part of these studies. Currently, different organisations collect their own 3D input data as required in noise simulation in a semi-automated way, even if areas overlap. This is not efficient, but also differences in input data may lead to differences in the results of noise simulation which has a negative impact on the reliability of noise studies. To address this problem, this paper presents a methodology to automatically generate 3D input data as required in noise simulations (i.e. buildings, terrain, land coverage, bridges and noise barriers) from current 2D topographic data and point clouds. The generated data can directly be used in existing noise simulation software. A test with the generated data shows that the results of noise simulation obtained from our generated data are comparable to results obtained in a current noise study from practice. Automatically generated input data for noise simulation, as achieved in this paper, can be considered as a major step in noise studies. It does not only significantly improve the efficiency of noise studies, thus reducing their costs, but also assures consistency between different studies and therefore it improves the reliability and reproducibility. In addition, the availability of countrywide, standardised input data can help to advance noise simulation methods since the calculation method can be adopted to improved ways of 3D data acquisition and reconstruction.     

Integration of Hough Transform of lines and planes in the framework of conformal geometric algebra for 2D and 3D robot vision

This paper presents the application of 2D and 3D Hough Transforms together with conformal geometric algebra to build 3D geometric maps using the geometric entities of lines and planes. Among several existing techniques for robot self-localization, a new approach is proposed for map matching in the Hough domain. The geometric Hough representation is formulated in such a way that one can easily relate it to the conformal geometric algebra framework; thus, the detected lines and planes can be used for algebra-of-incidence computations to find geometric constraints, useful when perceiving special configurations in 3D visual space for exploration, navigation, relocation and obstacle avoidance. We believe that this work is very useful for 2D and 3D geometric pattern recognition in robot vision tasks.     

An autonomous mobile robot with a 3D laser range finder for 3D exploration and digitalization of indoor environments

Digital 3D models of the environment are needed in rescue and inspection robotics, facility managements and architecture. This paper presents an automatic system for gaging and digitalization of 3D indoor environments. It consists of an autonomous mobile robot, a reliable 3D laser range finder and three elaborated software modules. The first module, a fast variant of the Iterative Closest Points algorithm, registers the 3D scans in a common coordinate system and relocalizes the robot. The second module, a next best view planner, computes the next nominal pose based on the acquired 3D data while avoiding complicated obstacles. The third module, a closed-loop and globally stable motor controller, navigates the mobile robot to a nominal pose on the base of odometry and avoids collisions with dynamical obstacles. The 3D laser range finder acquires a 3D scan at this pose. The proposed method allows one to digitalize large indoor environments fast and reliably without any intervention and solves the SLAM problem. The results of two 3D digitalization experiments are presented using a fast octree-based visualization method.     

From tabular data to knowledge graphs: A survey of semantic table interpretation tasks and methods

Tabular data often refers to data that is organized in a table with rows and columns. We observe that this data format is widely used on the Web and within enterprise data repositories. Tables potentially contain rich semantic information that still needs to be interpreted. The process of extracting meaningful information out of tabular data with respect to a semantic artefact, such as an ontology or a knowledge graph, is often referred to as Semantic Table Interpretation (STI) or Semantic Table Annotation. In this survey paper, we aim to provide a comprehensive and up-to-date state-of-the-art review of the different tasks and methods that have been proposed so far to perform STI. First, we propose a new categorization that reflects the heterogeneity of table types that one can encounter, revealing different challenges that need to be addressed. Next, we define five major sub-tasks that STI deals with even if the literature has mostly focused on three sub-tasks so far. We review and group the many approaches that have been proposed into three macro families and we discuss their performance and limitations with respect to the various datasets and benchmarks proposed by the community. Finally, we detail what are the remaining scientific barriers to be able to truly automatically interpret any type of tables that can be found in the wild Web.     

Constructing Isosurfaces from 3D Data Sets Taking Account of Depth Sorting of Polyhedra

Creating and rendering intermediate geometric primitives is one of the approaches to visualisze data sets in 3D space.Some algorithms have been developed to construct isosurface from uniformly distributed 3D data sets.These algorithms assume that the function value varies linearly along edges of each cell.But to irregular 3D data sets,this assumption is inapplicable.Moreover,the detth sorting of cells is more complicated for irregular data sets,which is indispensable for generating isosurface images or semitransparent isosurface images,if Z-buffer method is not adopted.In this paper,isosurface models based on the assumption that the function value has nonlinear distribution within a tetrahedron are proposed.The depth sorting algorithm and data structures are developed for the irregular data sets in which cells may be subdivided into tetrahedra.The implementation issues of this algorithm are discussed and experimental results are shown to illustrate potentials of this technique.     

基于工业CT体数据的三维测量方法研究

采用工业CT体数据,研究了三维图像空间的距离、角度、平面面积、曲面表面积、目标区域容积等几何参数的精确测量方法,并将图像空间的测量结果转换到物理空间,从而实现了产品内部结构几何尺寸的测量。结合某标准工件模型,通过实例比较了该文方法的测量结果和实际尺寸的差别,结果表明该文方法具有较高测量精度。     

数字孪生水下三维实景数据底板获取技术研究

为了获取高精度的水下三维模型细节纹理结构,满足数字孪生建设对水下三维实景数据底板获取的需求,实现对水下构筑物的实时可视化动态监测,基于GNSS技术、USBL技术研究构建了水陆一体化定位技术,融合水陆一体化定位技术、有缆ROV和水下摄影测量设备等研发了水下摄影测量系统,实现了数字孪生水下三维实景数据底板的获取,并采用多波束测深系统、水下三维全景成像声纳系统等对水下摄影测量系统获取的三维实景模型数据成果精度进行了验证,结果表明：水下摄影测量系统获取的三维实景模型精度满足规范要求,可用于数字孪生流域、工程等水下基础数据底板的建设,也可为水下高精度三维场景重构再现和水利工程水下构筑物实时动态监测提供技术支撑。