UGS4．0（for Windows）通用符号绘图软件简介

ＵＧＳ４．０（ｆｏｒ　Ｗｉｎｄｏｗｓ）通用符号绘图软件简介１ＵＧＳ４．０（ｆｏｒＷｉｎｄｏｗｓ）的用途本系统提供符号库（ＳＹＭＤＢ）与符号绘图（ＵＧＳＹＭ）两大软件，是Ｗｉｎｄｏｗｓ和ＢｏｒｌａｎｄＣ＋＋环境下开发图形软件，或开发ＧＩＳ等的图形输出模...     

自动安平（归零）补偿器补偿性能测试台的研制

自动安平（归零）补偿器性能测试台精度可达０．１秒级,可用于ＤＺＳＩ、ＤＺＳ３级水准仪和ＤＪ１、ＤＪ２级经纬仪的补偿器精度测试。     

天文改算方法的研究

根据“联合平差”的要求，对天文计算成果要进行统一归算。本文推导出新天文常数、系统对恒星视位置影响的计算公式，并进行了试算；然后通过新旧系统天文点的试算分析，导出了天文点改算模型；最后对ＪＹＤ和ＩＲＰ两极坐标系统进行了分析，确定了两极坐标系统差。     

红线与曲线交点的坐标计算与定位

红线与曲线交点的坐标计算与定位郭宗河（青岛建筑工程学院测量教研室２６６０３３）在实际工作中,我们有时会碰到如图１所示的情况,Ａ路为市政规划道路,Ｂ路为某单位自用的进场道路。已知两路中线ＪＤ～Ａ、ＪＤ～Ｂ的方位角１、２,交点坐标ＸＪＤ、ＹＪＤ,两路...     

我国经度原点经度改正值的重新归算

本文用１９７６年天文常数系统，１９８０年章动模型和ＦＫ５星表，重新归算了我国经度原点对应于不同极原点的经度改正值，计算中考虑了星表、固体潮、海潮的影响，其结果为（观测的平均历元为１９７５年３月２９．３０日）Δλ（ＣＩＯ）＝２６．７ｍｓ±１．４ｍｓΔλ（ＪＹＤ）＝３０．９ｍｓ±１．４ｍｓΔλ（ＭＰ）＝３１．３ｍｓ±１．４ｍｓ     

1949．0至1979．0 ILS地极坐标的均匀化

自１９８４年起在天文计算中都采用ＦＫ５基本星表和新天文常数,这些变动直接影响了用天顶仪等光学仪器观测订定的地极坐标。本文论述了基本星表和天文常数变动后,对国际纬度服务（ＩＬＳ）订定的地极坐标的影响。结果表明：１）星表系统差对地极坐标的影响在ｘ和ｙ方向最大,分别约－０．００６”和－０．００４”;２）章动序列变动的影响在ｘ、ｙ方向最大波动分别为０．０１２”和０．０１０”。     

基于JDBC的WebGIS异构数据库存取技术

本文详细地介绍了ＪＤＢＣ技术的特点及其于ＪＤＢＣ技术的ＷｅｂＧＩＳ异构数据库存取技术,略述了ＪＤＢＣ技术的实现过程。     

DJHT系统在数字化测图中的应用

本文介绍了作者应用ＤＪＨＴ系统进行数字化测图的情况。实践证明，尽管该系统尚有不完善之外，但是只要注意准确地输入了电子手簿数据，正确地绘制草图和及时生成并编辑图形，是可以获得高质量数字化产品的。     

DJHT系统在数字化测图中的应用

本文介绍了作者应用ＤＪＨＴ系统进行数字化测图的情况。实践证明，尽管该系统尚有不完善之处，但是只要注意准确地输入电子手簿数据、正确地绘制草图和及时生成并编辑图形，是可以获得高质量数字化产品的。     

矢量图形与主数据库无缝连接万维网地理信息系统的设计…

首先介绍了万维网地理信息系统、Ｊａｖａ和ＪＤＢＣ，讨论了目前万维网地理信息系统的才实验方法以及存在的问题，提出了矢量图形与主数据库无缝连接模型，并全用Ｊａｖａ和ＪＤＢＣ设计实现了万维网地理信息系统软件，使客户在客户端实现放大等地理空间分析功能。     

几种不同坐标变换方法问题的研究

三维或二维坐标转换常采用相似变换，然而相似变换只能解决不同坐标系统之间定义上的差异，坐标系统局部形变系统性误差往往未能反应到转换模型中，因此本文试图从多种变换方法展开讨论，提出了采用相似变换与正形变换的理论解决坐标系统局部形变系统性误差，同时对选择模型参数提出了统计假设检验方法。最后得出一些有益的结论。     

大范围GNSS水准与重力场模型间的系统偏差校正

大范围GNSS水准数据是评估重力场模型精度的重要独立数据源，通常大范围GNSS水准数据与地球重力场模型所对应的大地水准面不一致，导致两者间会存在系统偏差，该系统偏差会影响直接利用GNSS水准数据评估重力场模型精度的效果。本文以利用美国24 152个GNSS水准数据评估EIGEN-6C4重力场模型精度为例，提出采用分区常系统偏差校正法和四、五、七参数校正法校正两者间的系统偏差。试验结果表明，分区常系统偏差校正法和四、五、七参数校正法均可以有效校正两者间的系统偏差，系统偏差校正后，2160阶次的EIGEN-6C4模型在美国区域内的高程异常精度优于10 cm。     

A coordinate-invariant model for deforming geodetic networks: understanding rank deficiencies,non-estimability of parameters,and the effect of the choice of minimal constraints

By considering a deformable geodetic network, deforming in a linear-in-time mode, according to a coordinate-invariant model, it becomes possible to get an insight into the rank deficiency of the stacking procedure, which is the standard method for estimating initial station coordinates and constant velocities, from coordinate time series. Comparing any two out of the infinitely many least squares estimates of stacking unknowns (initial station coordinates, velocity components and transformation parameters for the reference system in each data epoch), it is proven that the two solutions differ only by a linear-in-time trend in the transformation parameters. These pass over to the initial coordinates (the constant term) and to the velocity estimates (the time coefficient part). While the difference in initial coordinates is equivalent to a change of the reference system at the initial epoch, the differences in velocity components do not comply with those predicted by the same change of reference system for all epochs. Consequently, the different velocity component estimates, obtained by introducing different sets of minimal constraints, correspond to physically different station velocities, which are therefore non-estimable quantities. The theoretical findings are numerically verified for a global, a regional and a local network, by obtaining solutions based on four different types of minimal constraints, three usual algebraic ones (inner or partial inner) and the lately introduced kinematic constraints. Finally, by resorting to the basic ideas of Felix Tisserand, it is explained why the station velocities are non-estimable quantities in a very natural way. The problem of the optimal choice of minimal constraints and, hence, of the corresponding spatio-temporal reference system is shortly discussed.     

Dependency of geodynamic parameters on the GNSS constellation

Significant differences in time series of geodynamic parameters determined with different Global Navigation Satellite Systems (GNSS) exist and are only partially explained. We study whether the different number of orbital planes within a particular GNSS contributes to the observed differences by analyzing time series of geocenter coordinates (GCCs) and pole coordinates estimated from several real and virtual GNSS constellations: GPS, GLONASS, a combined GPS/GLONASS constellation, and two virtual GPS sub-systems, which are obtained by splitting up the original GPS constellation into two groups of three orbital planes each. The computed constellation-specific GCCs and pole coordinates are analyzed for systematic differences, and their spectral behavior and formal errors are inspected. We show that the number of orbital planes barely influences the geocenter estimates. GLONASS’ larger inclination and formal errors of the orbits seem to be the main reason for the initially observed differences. A smaller number of orbital planes may lead, however, to degradations in the estimates of the pole coordinates. A clear signal at three cycles per year is visible in the spectra of the differences between our estimates of the pole coordinates and the corresponding IERS 08 C04 values. Combinations of two 3-plane systems, even with similar ascending nodes, reduce this signal. The understanding of the relation between the satellite constellations and the resulting geodynamic parameters is important, because the GNSS currently under development, such as the European Galileo and the medium Earth orbit constellation of the Chinese BeiDou system, also consist of only three orbital planes.     

Geodetic and geophysical implications of the homogeneous reduction of pole coordinates (1899–1979)

The new series ILS (H) of pole coordinates (1899.9–1979.0) computed in a homogeneous system has been employed for the determination of the period of Chandler's component of polar motion. The comparison with a value derived from a previous series ILS (VY) shows there is no significant variation in the period in spite of the known systematic errors affecting the ILS (VY) series. Any high precision geodetic network adjustment has to take account of the pole coordinates defined by the ILS (H) series. Such long series permitted the identification of another component of polar motion with a period of about 30 years. The polhode derived from the ILS (H) series shows greater regularity than previously deduced polhodes and, therefore, we can conclude that past investigations in geodesy and geophysics trying to correlated the irregularities of the polhode with different geophysical phenomena, for instance, earthquakes, may have to be revised.     

基于虚拟观测值的伪距差分方法研究

针对当前伪距差分服务观测值双差模式基准站坐标涉密不能在线传输与伪距改正数模式标准格式无法兼容北斗卫星导航系统（BDS）的问题,本文基于局域连续运行参考站（CORS）网数据,生成虚拟格网综合伪距改正数,并进一步生成虚拟伪距观测值,向用户实时播发虚拟观测值与站点坐标,用于用户差分定位．实验证明,虚拟格网伪距观测值差分可为用户提供平面亚米级、垂直优于1.5 m的定位服务．对实验数据进行分析,给出了格网差分最优配置方案．本文方法在解决上述两个问题的基础上由于服务端计算压力恒定,不受用户数限制,从算法上解决了大量用户并发接入服务的问题．      

Direct georeferencing of oblique and vertical imagery in different coordinate systems

Reconstruction of 3D models through integrating vertical and oblique imagery has been studied extensively. For a 3D reconstruction, object point cloud coordinates could be calculated using direct georeferencing (DG) obtained from the direct orientation data of a GPS/INS system. This paper implemented DG approaches for vertical and oblique imagery in the earth centered earth fixed frame (e-frame), local tangent frame (l-frame), and map projection frame (p-frame), respectively. In the p-frame, the earth curvature correction formulas were derived through naturalizing oblique imagery to vertical imagery to achieve a high positioning precision. Five basic stereo-pair models for vertical and oblique imagery were simulated to verify the positioning accuracy of different frames. Simulation experiments showed that DG in the e-frame and l-frame of these five scenarios were rigorous, and no systematic errors were imported by the DG model as these frames are Cartesian. DG in the p-frame has obvious systematic errors which are aroused by the earth curvature and projection deformation unconformity in the vertical and horizontal directions. These errors, however, can be compensated effectively through correcting image coordinates of the oblique imagery by extending the standard image coordinate correction approach and the exterior orientation (EO) height term. After the correction, the absolute positioning error is lower than 1/20 GSD for simulation test-1. In the p-frame, the process is straightforward, and it is convenient for producing maps. For high accuracy DG, though, it is recommended to adopt e-frame or l-frame options.     

IAU2000决议对卫星轨道的影响

研究了IAU2000对GPS卫星轨道确定的影响。以2006年DOY186的GPS数据为例,分析了GPS卫星在IAU2000决议模型以及原有模型下,惯性参考系统以及地固坐标系中轨道的差别。结果显示,采用不同模型,卫星轨道在惯性参考系中的差值存在周期性,其中X、Z方向的幅度达到了2.5 m,Y方向的幅度约为1 m;在地固系中,轨道差别也存在周期,幅度约为4 mm。并对卫星轨道的差值进行了统计,得出了在惯性系下,不同模型引起轨道差值的3D RMS为m级。     

Affine distortion of small GPS networks with large height differences

GPS is a promising tool for real-time monitoring of deformations of slopes or large structures. However, remaining systematic effects in GPS phase observations after double differencing and application of a priori models affect the resulting coordinates. They complicate the proper separation of the actual deformations from pseudo-deformations induced by the systematic effects. This paper shows that for small monitoring networks (baseline lengths <5 km) only affine distortions of the network geometry are generated by the remaining distance dependent systematic effects, e.g. unmodelled tropospheric and ionospheric propagation effects, or satellite orbit errors. Hence, a generic correction model is given by a three-dimensional affine transformation involving a maximum of 12 transformation parameters. For the determination of these parameters, four high quality GPS stations are necessary which are not affected by the actual deformations to be monitored. Based on the analysis of network geometries of synthetic GPS networks with large height differences and considering the physics of the GPS observations it is shown, however, that less than 12 parameters are sufficient for the computation of the corrections. The proposed 8 parameter model was applied to the GPS monitoring network of the Gradenbach landslide. For this small network with large height differences, it was shown that the distortions can be reduced by about 75%.