基于精密三角高程测量的基坑变形监测方法研究     

喜文飞  史正涛 《测绘与空间地理信息》2013,(10):263-265

传统的基坑监测中,几何水准测量工作效率低,任务量大。针对这些不足,本文采用一种新的三角高程测量方法进行变形监测,该方法可以使全站仪在任意点设站,减少了工作量,在测量中,不用量取仪器高、棱镜高,减少了三角高程测量中的误差来源,提高了精度。通过分析三角高程测量的精度,验证了精密三角高程测量代替几何水准测量的可行性与可靠性,结合基坑监测实例,将三角高程测量的数据与几何水准测量的数据进行比较．比较的结果显示,该三角测量方法结合精密全站仪可以替代几何水准测量,在实际工作中具有一定的适用性和参考价值。  相似文献   

基于特征约束的点云简化算法研究     

谢波  郑德华 《测绘与空间地理信息》2013,(12):163-165

针对传统的点云简化算法导致特征区域容易丢失的问题,提出了一种新的基于特征约束的点云简化的算法。首先对散乱点云用KD—TREE建立起空间拓扑关系,在此基础上建立起单个点的K-邻域。然后对K-邻域内建立起最小二乘平面,设定合理的阈值来度量数据点的重要性。依据特征点的分布估算每个点的简化距离阈值,以此为基础对每个点进行自适应简化。实验证明该算法能满足在点云数据简化过程中检测并保留特征点的要求。  相似文献   

一种基于CityGML的三维模型单体化方法     

倪晓东  梁君达  吴龙祥  刘沐洋 《测绘通报》2022,(12):29-34

实景三维中国建设应满足自然资源管理与社会经济发展需求,因此需要对基础地理信息产品进行实体化改造,三维模型单体化正是实体化改造的关键环节。本文提出了一种基于CityGML的三维模型单体化方法,首先根据地物实体轮廓的二维矢量面提供的顶点坐标及高程信息,构造墙面、屋顶等多边形平面组成地物的简单三维表达,然后配合渲染到纹理技术（RTT）进行纹理贴图,基于CityGML为每个二维矢量面对应的地物重构出有语义、有LOD层级的三维模型。该方法能够高效地实现三维模型单体化,且成果模型容量小,可满足各种实景三维应用需求。  相似文献   

保持移动速度特征的轨迹线化简方法     

杨敏  陈媛媛  金澄  程前 《测绘学报》2017,46(12):2016-2023

轨迹线数据实施化简处理对于缓解数据存储、传输压力以及后期的分析可视化效率具有重要意义。常规方法(如Douglas-Peucker算法)主要考虑线目标的几何形态结构,直接应用到轨迹线化简中容易丢失移动物体的运动状态特征。本研究从保持轨迹线隐含速度特征出发,提出了一种基于移动速度相似性原则的轨迹线层次化剖分与分区化简处理方法。首先,以相邻轨迹点构成的直线段为基本单元,在拓扑连接关系约束下基于速度指标对轨迹直线段进行层次化聚类,并将聚类结果组织为层次树结构;然后,以建立的层次树结构为约束条件对原始轨迹线实施分区处理,使得同一区域内轨迹线片段的中间点距首尾基准线的最大时间同步偏移距离小于设定的阈值;最后,依次连接各分区轨迹线片段首尾点导出化简结果。采用真实的车辆轨迹线作为试验数据,通过与其他多种方法进行对比分析验证了本文提出方法的有效性。  相似文献   

Visual Abstraction and Stylisation of Maps     

《The Cartographic journal》2013,50(1):8-18

Abstract

We explore visual map abstraction for the generation of stylized renderings of 2D map data. We employ techniques that are centred around the concept of shape simplification and graph layout and that allow iterative abstraction of 2D maps. We use data from publicly available sources and show how we can iteratively generate aesthetic renditions of these maps. These renditions do not have the goal to allow for navigation tasks, but instead show the map data in a distorted manner. The techniques used to create these images apply simplification, abstraction/generalisation, and displacement operations to the map elements in varying orders and add stylistic shading to produce aesthetic renditions for print or electronic displays. The degree of abstraction/generalisation can be individually chosen and determines the characteristics of the distorted map: whether components retain their shape, degenerate, or are processed in a manner that the abstraction becomes the focus of the image rather than the underlying map data. The renditions can be further personalized by choosing shading and colours for this shading. Together, the presented techniques allow for playful and creative exploration of aesthetic renditions of 2D map data.  相似文献   

山东数字地震台站场地响应估算   总被引：1，自引：0，他引：1  

蔡寅  林秀娜  穆娟  曲保安 《地震地磁观测与研究》2013,(5):98-103

为了建立山东省数字地震台站场地响应数据库,选取山东区域数字地震台网自2009年4月至2012年1月记录的ML≥2.5地震事件,通过信噪比方法挑选出质量较高的86次地震,采用互相衔接的三段几何衰减模型,基于遗传算法,利用Moya等方法对山东省36个地震台站进行场地响应测算.其中35个台站未显示明显的放大作用,聊城台场地响应变化起伏较大,高频部分放大明显,烟台、招远、即墨、五连、菏泽台场地响应总体表现出一定衰减作用.  相似文献   

Multicriteria generalization (MCG): a decision-making framework for formalizing multiscale environmental data reduction     

Gaurav Sinha  Warit Silavisesrith 《International journal of geographical information science》2013,27(5):899-922

Environmental simulation models need automated geographic data reduction methods to optimize the use of high-resolution data in complex environmental models. Advanced map generalization methods have been developed for multiscale geographic data representation. In the case of map generalization, positional, geometric and topological constraints are focused on to improve map legibility and communication of geographic semantics. In the context of environmental modelling, in addition to the spatial criteria, domain criteria and constraints also need to be considered. Currently, due to the absence of domain-specific generalization methods, modellers resort to ad hoc methods of manual digitization or use cartographic methods available in off-the-shelf software. Such manual methods are not feasible solutions when large data sets are to be processed, thus limiting modellers to the single-scale representations. Automated map generalization methods can rarely be used with confidence because simplified data sets may violate domain semantics and may also result in suboptimal model performance. For best modelling results, it is necessary to prioritize domain criteria and constraints during data generalization. Modellers should also be able to automate the generalization techniques and explore the trade-off between model efficiency and model simulation quality for alternative versions of input geographic data at different geographic scales. Based on our long-term research with experts in the analytic element method of groundwater modelling, we developed the multicriteria generalization (MCG) framework as a constraint-based approach to automated geographic data reduction. The MCG framework is based on the spatial multicriteria decision-making paradigm since multiscale data modelling is too complex to be fully automated and should be driven by modellers at each stage. Apart from a detailed discussion of the theoretical aspects of the MCG framework, we discuss two groundwater data modelling experiments that demonstrate how MCG is not just a framework for automated data reduction, but an approach for systematically exploring model performance at multiple geographic scales. Experimental results clearly indicate the benefits of MCG-based data reduction and encourage us to continue expanding the scope of and implement MCG for multiple application domains.  相似文献   

一种基于曲率的线状目标简化算法     

刘钊  高培超  施洪刚  王永红 《测绘科学》2014,39(10)

线要素是GIS中常见的数据类型,其抽稀简化算法在尺度变换、制图综合等领域应用广泛.文章介绍了SimpliPoly算法的具体原理,并在实现该算法的基础上,研究了SimpliPoly算法应用过程中的关键问题:阀值确定与三维扩展;提出了快速确定阀值组合的方法,并将该算法扩展至三维线状目标简化.结果表明,阀值组合确定方法快速、有效,三维扩展方法简单、实用,在三维空间中延续了二维SimpliPoly算法的优点.  相似文献   

A simplified multisupport response spectrum method     

Jihong Ye  Zhiqiang Zhang  Xianming Liu 《地震工程与工程振动(英文版)》2012,11(2):243-256

A simplified multisupport response spectrum method is presented.The structural response is a sum of two components of a structure with a first natural period less than 2 s.The first component is the pseudostatic response caused by the inconsistent motions of the structural supports,and the second is the structural dynamic response to ground motion accelerations.This method is formally consistent with the classical response spectrum method,and the effects of multisupport excitation are considered for any modal response spectrum or modal superposition.If the seismic inputs at each support are the same,the support displacements caused by the pseudostatic response become rigid body displacements.The response spectrum in the case of multisupport excitations then reduces to that for uniform excitations.In other words,this multisupport response spectrum method is a modification and extension of the existing response spectrum method under uniform excitation.Moreover,most of the coherency coefficients in this formulation are simplified by approximating the ground motion excitation as white noise.The results indicate that this simplification can reduce the calculation time while maintaining accuracy.Furthermore,the internal forces obtained by the multisupport response spectrum method are compared with those produced by the traditional response spectrum method in two case studies of existing long-span structures.Because the effects of inconsistent support displacements are not considered in the traditional response spectrum method,the values of internal forces near the supports are underestimated.These regions are important potential failure points and deserve special attention in the seismic design of reticulated structures.  相似文献   

一种基于面积平衡约束的图斑化简算法   总被引：1，自引：0，他引：1  

李建林  朱德海  宋晓眉  陈亚婷  杨扬 《地理与地理信息科学》2009,25(1)

保持综合前后各地类土地面积平衡是土地利用数据综合的基本原则.地类图斑是面积统计的最小单元,用常规的线化简算法不但难以保证图斑的地理特性,而且会给面积统计带来不确定性.该文提出一种能够使图斑化简前后面积保持绝对平衡的化简算法,该算法给出了求取图斑群和岛图斑的地理特征点、几何特征点的相关方法,对被特征点分割的综合子弧段运用直线面积平衡和参数曲线面积平衡两种求取平衡线的方式进行化简,基本原理是综合前后弧段切割它们自身的包络矩形面积比相等,且综合后的弧段须落入综合前子弧段的误差缓冲区内.实验表明,该算法不但能保持图斑的形态特征,而且能保持图斑化简前后面积绝对相等.  相似文献