融合多源重力数据构建局部高阶重力场模型

针对利用带限型径向基函数,融合航空和地面重力数据构建高阶地球重力场模型时,航空、地面重力数据的频谱信息不一致问题,该文提出残差与先验精度比较分析法,确定出了研究区域航空数据的最佳频谱范围.结果 表明:航空重力数据系统性偏差及其径向基函数展开阶次不当可分别导致±0.019m和±0.007 m的建模误差.基于此,构建了局部区域6000阶的径向基函数融合地球重力场模型CBFM2020.通过与GPS/水准数据比较,CBFM2020的精度比EGM2008、USGG2012以及仅由地面数据得到的重力场模型均有所提高.模型建立过程中航空重力数据未进行向下延拓,而是直接在原始高度与地面数据进行融合,可为局部地区高阶重力场模型的构建提供一定参考.     

On the spatial distribution of buildings for map generalization

Information on spatial distribution of buildings must be explored as part of the process of map generalization. A new approach is proposed in this article, which combines building classification and clustering to enable the detection of class differences within a pattern, as well as patterns within a class. To do this, an analysis of existing parameters describing building characteristics is performed via principal component analysis (PCA), and four major parameters (i.e. convex hull area, IPQ compactness, number of edges, and smallest minimum bounding rectangle orientation) are selected for further classification based on similarities between building characteristics. A building clustering method based on minimum spanning tree (MST) considering rivers and roads is then applied. Theory and experiments show that use of a relative neighbor graph (RNG) is more effective in detecting linear building patterns than either a nearest neighbor graph (NNG), an MST, or a Gabriel graph (GssG). Building classification and clustering are therefore conducted separately using experimental data extracted from OpenStreetMap (OSM), and linear patterns are then recognized within resultant clusters. Experimental results show that the approach proposed in this article is both reasonable and efficient for mining information on the spatial distribution of buildings for map generalization.     

非差非组合精密单点定位提取区域电离层延迟及精度评定

电离层延迟是GNSS定位中最难处理,也是很重要的的误差来源之一,目前常用线性组合的方式处理电离层延迟,这些方法都会引入多余噪声,在不同程度上影响了模糊度的整数特性,同时也造成了某些有用数据丢失。本文提出了一种基于非差非组合精密单点定位的方式提取区域参考站电离层延迟的方法,再将提取得到的区域电离层延迟内插至仿用户站,在仿用户站实施单频PPP,最后检验得到定位的精度。实验结果表明:仿用户站单频PPP的定位精度平面方向约为4—5 cm,在高程方向低于1 dm,与全球电离层格网模型和半和改正等模型相比,采用非差非组合的方法提取电离层延迟后的定位精度更高。     

Estimation of antenna phase center offset for BDS IGSO and MEO satellites

The BeiDou satellite navigation system (BDS) is different from other global navigation satellite systems (GNSSs) because of its special constellation, which consists of satellites in geostationary earth orbit, inclined geosynchronous earth orbit (IGSO), and medium earth orbit (MEO). Compared to MEO satellites, the observations of IGSO satellites cover only a small range of nadir angles. Therefore, the estimation of phase center offsets (PCOs) suffers from high correlation with other estimation parameters. We have estimated the phase center offsets for BeiDou IGSO and MEO satellites with a direct PCO parameters model, and constraints are applied to cope with the correlation between the PCOs and other parameters. Validation shows that the estimated PCO parameters could be used to improve the accuracy of orbit and clock offset overlaps. Compared with the Multi-GNSS Experiment antenna phase center correction model, the average improvements of the proposed method for along-track, cross-track, and radial components are 19 mm (31%), 5 mm (14%), and 2 mm (15%) for MEO satellites, and 13 mm (17%), 12 mm (21%), and 5 mm (19%) for IGSO satellites. For clock offset overlaps, average improvements of standard deviation and root mean square (RMS) are 0.03 ns (20%) and 0.03 ns (12%), respectively. The RMS of precise coordinates in the BDS-only positioning was also improved significantly with a level of 24 mm (30%) in the up-direction. Finally, the overall uncertainty of the estimated results is discussed.     

基于自适应中心加权中值和Goldstein的InSAR干涉图强噪声滤波方法

针对现有的滤波方法在处理强噪声干涉图时的不足,提出一种基于自适应中心加权中值和Goldstein的两步干涉图滤波方法。试验结果表明,构造的针对强噪声干涉图的两步滤波法在滤除噪音的同时,可以很好地保存干涉图的条纹信息。与经典的Goldstein方法相比,新方法的滤波效果可以提高22.4%和43.6%。     

强噪声SAR干涉图的等值线中值–Goldstein 二级滤波

结合等值线滤波条纹边缘保持能力强和Goldstein滤波平滑效果好的特点,并且引入伪相干值对Goldstein滤波因子进行改进,提出InSAR干涉图的等值线中值-Goldstein二级滤波方法.模拟数据和真实数据的实验结果证明,强噪声干涉图经过新方法滤波后噪声水平大大降低而且分布均匀,条纹细节信息保持良好,在原本看不到...     

顾及结构特征的建筑物图形迭代凸分解方法

针对建筑物图形,该文提出了一种结合其形态表达特点的迭代凸分解方法.该方法利用Delaunay三角网提取建筑物图形凹部层次化结构和骨架线定义图形节点凹度,并依据建筑物图形直角化和简洁表达的特点选取分割线迭代消除当前图形中凹度最大节点实现图形凸分解.实验结果表明,该文方法能有效实现带洞(或岛)建筑物图形的凸分解,结果符合视...     

哈尔滨市交通导航系统的研究与应用

在哈尔滨市8个行政区范围内建立5个永久性连续运行GNSS基准站,各基准站观测数据通过专用数据通信网传送至数据管理中心,经过处理后实时通过专用网或因特网向导航用户发布国际通用格式的差分数据,以满足导航用户对高精度实时定位、测速、位移测量的要求,实现物流配送、公共安全、交通导航等现代化管理。     

基于GIS的公交IC卡数据处理及分析系统

公交数据库里潜含着反映公交运营状况的客流信息,对其进行分析可以为公交线网优化和交通管理提供依据。以北京市为例,在VC＋＋2005开发平台上,利用SQLServer数据库和ArcSDE开发出基于GIS的公交IC卡数据处理及分析系统,不仅能够实现GIS的一般功能,还改进了公交／地铁换乘处理标准,实现全网断面客流以及全网速度的显示。     

InSAR三维同震地表形变监测——窗口优化的SM-VCE算法

三维同震地表形变场对于地震形变特征解译和断层滑动分布反演具有重要意义.本文基于地表应力应变模型(SM)和方差分量估计(VCE)的InSAR三维地表形变监测方法(SM-VCE),通过顾及一定窗口范围内不同像素点三维形变之间的力学关系(SM)建立函数模型,显著增加了多余观测个数,进而可利用VCE实现不同类InSAR观测值之间的精确定权.相比于传统的单点解算方法,基于窗口的SM-V CE方法可显著提高三维地表形变的估计精度.在原始SM-V CE方法中,求解不同目标点的三维形变时,窗口大小是固定不变的,并且窗口内的I nSAR观测值被认为是等精度的.对于同震形变场而言,I nSAR技术在地震破裂带附近往往难以获得有效的形变监测结果,使得固定窗口大小的SM-V CE方法无法获取完整的三维同震地表形变.即使在断层附近有I nSAR观测值的情况下,窗口内往往会包含断层两侧的异质InSAR观测值,使得原始SM-VCE方法难以得到可靠的近场三维形变.同时,InSAR观测值极易受到失相干等噪声影响,窗口内不同像素点的形变测量值精度往往各不相同,因此,忽略窗口内I nSAR观测值精度差异的做法将会降低三维地表形变精度.鉴于此,本文在SM-V CE方法的框架下,提出一种顾及断裂线及自适应变化搜索窗口的观测值选取策略,进而基于邻近的I nSAR有效观测值重建地震破裂带附近的三维地表形变场;引入迭代加权最小二乘方法实现窗口内同一类I nSAR观测值内部的自适应定权,有效降低了误差较大的观测值对三维地表形变精度的影响.模拟试验和基于升降轨哨兵数据的2019年Ri dgecrest地震研究表明,相对于原始SM-VCE方法,本文提出的窗口优化SM-V CE方法获取的三维同震地表形变场更加精确、完整.