共查询到20条相似文献，搜索用时 638 毫秒
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车载移动激光扫描测量瞬时外方位元素的确定精度决定了直接地理定向的精度。针对车载三维激光扫描测量高精度定位需要以及点云无组织特点带来的瞬时外方位元素解算无整体约束条件问题,本文提出一种统一测量基准下的瞬时外方位元素精确直接解算方法,经试验验证,瞬时外方位元素确定精度满足1:500测图或定位要求。 相似文献
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地面三维激光扫描是获取对象表面几何信息的主要方法之一,扫描对象的完整性是三维激光扫描数据获取的基本要求。为解决实际扫描过程中,因作业空间受限等原因引起的扫描死角而导致点云缺失的问题,本文根据平面镜反射光线原理提出了针对非直视区域的普通平面镜辅助激光扫描数据的获取方法。分析了普通平面镜对激光光束传播路径与距离的影响机理,推导了激光扫描经普通平面镜反射像点对应的物点坐标解算方程;顾及激光扫描特性,设计了包含球标靶和普通平面镜的镜面反射系统,阐述了系统构建、系统检校与系统坐标系构建方法;并通过试验验证了本方法的可行性和精度。 相似文献
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车载激光扫描技术可以快速获取地物表面的高精度三维信息,作为一种新的数据获取手段,已逐渐应用于地理信息系统产业中。将激光扫描数据分类是对地物进行特征提取以及建模的前提与关键。现今,针对车载激光扫描数据的分类方法还不成熟。根据城市各典型地物空间特征(激光点云在三维空间的高程、与邻近点的斜率,以及其在二维投影平面上的分布、密集程度等),本文提出一种主要适用于城市激光扫描数据的地物分类方法。首先,综合考虑车载激光数据的采集特点、车行GPS轨迹以及扫描数据中同一扫描线上相邻激光点之间的斜率关系,提取出路面。其次,对于非路面的激光点云数据,先使用基于格网化与区域分割相结合的方法进行实体划分,再通过计算地物空间形状特征的几项统计指标(外包围盒、实体高度等),对实体进行分类。最后,以海南三亚市某街道为研究区验证该方法的有效性。实验结果表明,使用该方法能成功地分出研究区的路面、建筑物、树木和路灯四类地物,并进一步在同类地物间分出不同实体。 相似文献
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针对运营隧道检测无全球导航卫星系统(GNSS)信号，移动激光扫描难以获取绝对坐标系下三维点云数据的问题，该文提出一种顾及靶标控制的高精度隧道移动扫描方法。并将三维激光扫描仪、惯导、里程计、倾角仪集成为自移动三维激光扫描系统，利用倾角仪静态测量姿态角约束惯导数据，结合控制点坐标纠正测量线路轨迹，生成绝对坐标系下的三维点云数据。通过与组合导航对比以及现场实验验证，该方法绝对定位点位偏差可以控制在0.06 m以内。研究方法解决了隧道场景绝对定位难题，有效避免了由于卫星信号遮挡隧道移动扫描点云明显变形和误差急剧变大等情况，为轨道交通隧道三维显示、病害检测等后续分析提供了良好的数据支撑。 相似文献
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针对复杂体育场馆外部精细建模在完整性和精度方面存在的问题，本文提出了地面控制、地面激光扫描、无人机建模控制一体化的高精度建模方法。首先应用特制标志建立区域内控制、扫描、无人机高精度一体化坐标系统；其次对地面多站激光扫描点云结合控制坐标进行区域整体平差配准，生成一体化坐标系统下高精度地面点云模型；然后应用无人机数据和控制点生成一体化坐标下的高精度顶部数据；最后融合两种数据生成对象完整高精度精细模型。试验证明，整体平差解算方法可实现多站点云的高精度配准，一体化控制可实现非同源异质数据高精度融合，解决了复杂建筑对象的高精度建模问题，具有很大的实用价值。 相似文献
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杨飞飞 《测绘与空间地理信息》2022,(2):103-106
随着智慧城市建设发展需求的不断扩大,移动扫描技术在项目应用中的频率不断提升,车载三维激光扫描技术以其高效率、高精度的特点已在项目实践中占有一席之地.但车载三维激光扫描技术受限于卫星信号等情况影响,点云数据为确保达到高精度,通常需进行远超车载扫描本身工作量的点云精度改善工作,即点云纠正,本文使用多个实例数据,通过对不同纠... 相似文献
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针对单个激光扫描头进行SLAM重建点云覆盖度较低的问题，提出一种融合双扫描头的SLAM方法。该方法首先使用水平扫描头进行一次SLAM过程，获取位姿轨迹数据和点云地图。再使用双扫描头间标定的外参数和水平点云帧的位姿轨迹数据，将竖直扫描头的点云帧位姿初步变换到水平点云坐标系下，通过提出的竖直点云-子图ICP(Iterative closest point)配准，动态优化转换参数，获取精确的转换参数实现两个方向点云数据的高精度融合。选择两栋室外建筑物进行试验，利用点云重建结果平面拟合均方根误差进行定量精度评定，结果表明，相比于传统单个水平激光扫描头建图方式，本方法重建的点云具有更加丰富的建筑物立面信息；相比于直接使用标定参数融合的方法，利用竖直点云-水平点云子图优化配准的方式优化，精度提高24%以上。 相似文献
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《International Journal of Digital Earth》2013,6(3):275-289
Abstract In recent years, geographical information systems have been employed in a wide variety of application domains, and as a result many research efforts are being devoted to those upcoming problems. Geospatial data security, especially access control, has attracted increased research interests within the academic community. The tendency towards sharing and interoperability of geospatial data and applications makes it common to acquire and integrate geospatial data from multiple organisations to accomplish a complex task. Meanwhile, many organisations have the requirement for securing access to possessed sensitive or proprietary geospatial data. In this heterogeneous and distributed environment, consistent access control functionality is crucial to promote controlled accessibility. As an extension of general access control mechanisms in the IT domain, the mechanism for geospatial data access control has its own requirements and characteristics of granularity and geospatial logic. In this paper, we address several fundamental aspects concerning the design and implementation of an access control system for geospatial data, including the classification, requirements, authorisation models, storage structures and management approaches for authorisation rules, matching and decision-making algorithms between authorisation rules and access requests, and its policy enforcement mechanisms. This paper also presents a system framework for realising access control functionality for geospatial data, and explain access control procedures in detail. 相似文献
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Automatic Registration Between Low-Altitude LiDAR Point Clouds and Aerial Images Using Road Features
Peipei He Xinjing Wang Youchuan Wan Jingzhong Xu Wei Yang 《Journal of the Indian Society of Remote Sensing》2018,46(12):1963-1973
Among the many means of acquiring surface information, low-altitude light detection and ranging (LiDAR) systems (e.g., unmanned aerial vehicle LiDAR, UAV-LiDAR) have become an important approach to accessing geospatial information. Considering the lower level of hardware technology in low-altitude LiDAR systems compared to that in airborne LiDAR, and the greater flexibility in-flight, registration procedures must be first performed to facilitate the fusion of laser point data and aerial images. The corner points and edges of buildings are frequently used for the automatic registration of aerial imagery with LiDAR data. Although aerial images and LiDAR data provide powerful support for building detection, adaptive edge detection for all types of building shapes is difficult. To deal with the weakness of building edge detection and reduce matching-related computation, the study presents a novel automatic registration method for aerial images, with LiDAR data, on the basis of main-road information in urban areas. Firstly, vector road centerlines are extracted from raw LiDAR data and then projected onto related aerial images with the use of coarse exterior orientation parameters (EOPs). Secondly, the corresponding image road features of each LiDAR vector road are determined using an improved total rectangle-matching approach. Finally, the endpoints of the conjugate road features obtained from the LiDAR data and aerial images are used as ground control points in space resection adjustment to refine the EOPs; an iterative strategy is used to obtain optimal matching results. Experimental results using road features verify the feasibility, robustness and accuracy of the proposed approach. 相似文献
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传统的河道测量工作量大、效率低、采样密度有限,其数据获取方式和数据处理模式已经不能满足河道信息化的需要。三维激光扫描技术为空间三维信息的获取提供了全新的技术手段。本文以焦作市新河为试验区,采用Riegl VZ-1000三维激光扫描仪获取枯水期河道数据,首先对获取的河道激光点云数据进行预处理,包括数据拼接、坐标转换、点云数据滤波分类处理等,采用反距离加权插值(IDW)算法生成DEM和基于DEM自动获取断面的方法,实现了河道断面的提取,并对断面数据进行了精度分析,建立了基于三维激光扫描技术的河道水上地形信息提取技术流程。 相似文献
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In this work we investigate the effectiveness of different types of visibility models for use within location‐based services. This article outlines the methodology and results for our experiments, which were designed to understand the accuracy and effects of model choices for mobile visibility querying. Harnessing a novel mobile media consumption and authoring application called Zapp, the levels of accuracy of various digital surface representations used by a line of sight visibility algorithm are extensively examined by statistically assessing randomly sampled viewing sites across the 1 km2 study area, in relation to points of interest (POI) across the University of Nottingham campus. Testing was carried out on three different surface models derived from 0.5 m LiDAR data by visiting physical sites on each surface model with 14 random point of interest masks being viewed from between 10 and 16 different locations, totalling 190 data points. Each site was ground‐truthed by determining whether a given POI could be seen by the user and could also be identified by the mobile device. Our experiments in a semi‐urban area show that choice of surface model has important implications for mobile applications that utilize visibility in geospatial query operations. 相似文献
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Population mobility patterns are important for understanding a city's rhythms. With the widespread use of mobile phones, population-based trajectories can be utilized to explore such mobility patterns. However, to protect personal privacy, mobile phone data must be de-identified by data aggregation within each spatiotemporal unit. In data acquired from mobile phones, population mobility features are still implicit in the spatiotemporally aggregated grid data. In this study, based on image-processing techniques, a two-step 3D gradient method is adopted to extract the movement features. The first step is to estimate the initial movement pattern in each spatiotemporal grid, and then to estimate the accumulated movement pattern within a time period around a geographical grid. This method can be applied adaptively to multi-scale spatiotemporal grid data. Using geospatial visualization methods, estimated motion characteristics such as velocity and flow direction can be made intuitive and integrated with other multiscale geospatial data. Furthermore, the correlation between the population mobility pattern and demographic characteristics, such as gender and age groups, can be analyzed with intuitive visualization. The implication of the visualization results can be used for understanding the human dynamics in a city, which can be beneficial for urban planning, transportation management, and socioeconomic development. 相似文献
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Accurate and robust positioning of vehicles in urban environments is of high importance for autonomous driving or mobile mapping. In mobile mapping systems, a simultaneous mapping of the environment using laser scanning and an accurate positioning using global navigation satellite systems are targeted. This requirement is often not guaranteed in shadowed cities where global navigation satellite system signals are usually disturbed, weak or even unavailable. We propose a novel approach which incorporates prior knowledge (i.e., a 3D city model of the environment) and improves the trajectory. The recorded point cloud is matched with the semantic city model using a point‐to‐plane iterative closest point method. A pre‐classification step enables an informed sampling of appropriate matching points. Random forest is used as classifier to discriminate between facade and remaining points. Local inconsistencies are tackled by a segmentwise partitioning of the point cloud where an interpolation guarantees a seamless transition between the segments. The general applicability of the method implemented is demonstrated on an inner‐city data set recorded with a mobile mapping system. 相似文献
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Ikonos-2在西藏的空间定位及其精度研究 总被引：1，自引：0，他引：1
研究了Ikonos-2卫星图像基于RPC模型的坐标基准转换、控制点布设及图像加密的方法,以便Iko-nos卫星图像能用于高精度地理数据采集和大比例尺地形图生产。 相似文献
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Machine learning allows “the machine” to deduce the complex and sometimes unrecognized rules governing spatial systems, particularly topographic mapping, by exposing it to the end product. Often, the obstacle to this approach is the acquisition of many good and labeled training examples of the desired result. Such is the case with most types of natural features. To address such limitations, this research introduces GeoNat v1.0, a natural feature dataset, used to support artificial intelligence‐based mapping and automated detection of natural features under a supervised learning paradigm. The dataset was created by randomly selecting points from the U.S. Geological Survey’s Geographic Names Information System and includes approximately 200 examples each of 10 classes of natural features. Resulting data were tested in an object‐detection problem using a region‐based convolutional neural network. The object‐detection tests resulted in a 62% mean average precision as baseline results. Major challenges in developing training data in the geospatial domain, such as scale and geographical representativeness, are addressed in this article. We hope that the resulting dataset will be useful for a variety of applications and shed light on training data collection and labeling in the geospatial artificial intelligence domain. 相似文献