检定场的机载激光雷达精度评价方法

为了对机载激光雷达测量精度进行科学地评价,保障数据成果质量,满足新型仪器装备计量检测的需要,该文基于空对地检定场圆形标志点,利用平均值法和最小外包圆法对机载激光雷达的平面精度和高程精度进行评价研究。结果表明:针对低空机载激光雷达可以获取高密度的地面点云,可以利用轮廓突出且特殊形状的控制点进行三维精度评价;利用平均值法和最小外包圆法均可以对机载激光雷达进行快速、有效地三维精度评价。     

Modelling forest canopy gaps using LiDAR-derived variables

Remote sensing has revolutionized forest management and has been widely employed to model canopy gaps. In this study, a canopy height model (CHM) and an intensity raster (IR) derived from light detection and ranging (LiDAR) data were used to model canopy gaps within a four-year-old Eucalyptus grandis forest using an object-based image analysis (OBIA) approach. Model thematic accuracies using the CHM, intensity raster and combined data set (CHM and IR) were all above 90%, with KHAT values ranging from 0.88 to 0.96. Independent test thematic accuracies were also above 90%, with KHAT values ranging from 0.82 to 0.91. A comparative area-based assessment yielded accuracies ranging from 70 to 90%, with the highest accuracies achieved using the combined data set. The results of this study show that using a CHM and intensity raster, and an OBIA approach, provides a viable framework to accurately detect and delineate canopy gaps within a commercial forest environment.     

A literature synthesis of LiDAR applications in transportation: feature extraction and geometric assessments of highways

Interest in using Light Detection and Ranging (LiDAR) technology in Transportation Engineering has grown over the past decade. The high accuracy of LiDAR datasets and the efficiency by which they can be collected has led many transportation agencies to consider mobile LiDAR as an alternative to conventional tools when surveying roadway infrastructure. Nonetheless, extracting semantic information from LiDAR datasets can be extremely challenging. Although extracting roadway features from LiDAR has been considered in previous research, the extraction of some features has received more attention than others. In fact, for some roadway design elements, attempts to extract those elements from LiDAR have been extremely scarce. To document the research that has been done in this area, this paper conducts a thorough review of existing studies while also highlighting areas where more research is required. Unlike previous research, this paper includes a thorough review of the previous attempts at data extraction from LiDAR while summarizing the detailed steps of the extraction procedure proposed in each study. Moreover, the paper also identifies common tools and techniques used to extract information from LiDAR for transportation applications. The paper also highlights common limitations in existing algorithms that could be improved in future research. This paper represents a valuable resource for researchers and practitioners interested in knowing the current state of research on the applications of LiDAR in the field of Transportation Engineering while also understanding the opportunities and challenges that lie ahead.     

基于LiDAR-DP的机载激光雷达数据处理

基于国产机载LiDAR数据处理软件LiDAR-DP,总结了机载LiDAR数据处理的技术流程,并根据该流程对LiDARDP的相关功能进行了研究。利用LiDAR-DP对实际数据进行了DEM生产试验,并与同类商业软件进行了功能对比。结果表明,LiDAR-DP是一款优秀的国产机载LiDAR数据处理软件,完全能满足DEM的生产需求。     

Trimble MX7移动测量系统精度影响因素分析

车载移动测量系统的测图精度受测量环境影响较大,而城市测量的环境一般较复杂,且环境对测量精度的影响程度并未明确,因此本文主要针对车辆在建筑物遮挡和拐弯两种情况下做了实验,同时对同一目标点的二维坐标和三维坐标进行了平面精度的对比,综合分析评价了Trimble MX7移动测量系统在实际应用中行驶轨迹精度和目标点位精度的变化情况。实验证明,轨迹拐弯处的点位精度比车辆直行时的点位精度差,但满足1∶1 000数字测图精度要求,在建筑遮挡最密集时点位精度最差但仍可应用于1∶1 000野外数字测图,直接对目标点的三维坐标进行提取的精度优于二维坐标提取方式,该测量系统可应用于1∶2 000野外数字测图的高程测量。     

车载移动测量系统在大比例尺地形图数学精度检测中的应用

研究了车载移动测量系统在大比例尺地形图数学精度检测中的应用。首先在小范围内对其进行了相关试验,得到其有效性后,对某市全市域的地形图进行了抽样检测;对车载移动测量检验与常规方法检验在外业数据采集、内业数据处理及存储量等几方面进行了比较,分析了车载移动测量检验方法的优劣性,为提高测绘质检效率提供了一种新方案。     

机载LiDAR点云获取与高精度DEM建设关键技术探讨

结合广东省机载LiDAR点云获取与高精度DEM建设项目,介绍了项目总体技术路线,针对项目难点,从设备选择、点云密度设计、植被覆盖密集山区数据获取方法、点云数据分类组合算法、空白区处理等5个方面的关键技术进行了探讨,并提出解决方案,为同类项目的设计与实施提供参考。     

多尺度邻域特征下的机载LiDAR点云电力线分类

利用机载激光雷达技术三维测量精度高且获取快速的优点进行电力线自动分类提取已成为点云数据处理与电力应用的重要领域。针对电力线分类模型的自动化和高精度需求,本文提出了基于三维多尺度邻域特征的机载LiDAR点云电力线分类提取模型框架,主要包括4个步骤：电力线候选点滤波、多尺度邻域类型选取、形状结构特征提取和支持向量机分类。通过对2个复杂城市区域的试验数据集和8种不同邻域类型的详细结果对比分析,发现基于多尺度圆球邻域形状结构特征的分类模型结果准确率、召回率和质量分别达到97%、94%和93%,同时整体处理时间在2个试验数据中分别从366、256 s减少到274、160 s。试验结果表明,该方法在多种复杂城市场景中能够实现机载LiDAR数据的电力线较高精度分类提取。     

车载激光雷达测量系统整体检校方法

针对目前系统检校常用方法中大多依赖手工提取点时无法准确获得检校点、绝对精度较低、对实际数据的适用性差等问题,该文结合自主研发的车载激光雷达测量系统,提出一种利用带有反射片的特制球形标靶及利用距离阈值插值算法快速、方便且准确地对车载激光雷达测量系统进行外参数检校的方法。结果表明:与传统方法相比,该方法可以完全弥补常规方法中提取的检校点不准确、精度低等缺点,适用性及实用性更强;在绝对精度方面,整体水平精度达到0.05m以下,高程精度达到0.06m以下;在相对精度方面,拟合检校球直径精度达到0.003m以下,距离精度达到0.002m以下,证明该方法的精度、适用性完全满足当前车载激光雷达测量系统检校的精度需求。     

3D SLAM的室内背包移动测量系统研究

针对室内移动测图中GPS信号缺失,导致无法获取精确定位坐标与导航的问题,该文研发了一套室内背包式移动测量系统,该系统能够利用三维激光定位与测图的方法实现快速同步定位及地图创建和室内三维激光点云获取,可以应用在室内或地下的环境中进行数据采集,在不损失作业效率的前提下获取系统作业轨迹、高精度点云等多种数据结果。为了对系统的精度进行验证,使用该系统在实验室大楼走廊中进行实验获取室内三维激光点云,并将实验结果与采用常规测量手段得到的结果进行对比分析。实验表明,此系统的相对精度和绝对精度分别能够达到0.048和0.047m,在室内三维信息获取过程中相比较于传统作业方式显著提高了作业效率和数据质量,能够满足室内建模与测图要求。