南极拉斯曼丘陵地区大地测量控制网

南极拉斯曼丘陵地区大地测量控制网的建立与施测前后共历经４年方始完成，总控制面积约１７７．６平方公里。本文主要讨论了该网分区布设情况及总体平差的原理与方法，并对成果进行了统计分析。经过整体平差的结果可以满足１：１００００测图的需要。该网的也是我国东南极中山于区的基础大地控制网。     

简述几种GPS控制网平差方法的优缺点

介绍了几种GPS控制网平差方法的优缺点,通过大连金州区航测数字化成图任务时所实施的的基础控制为例,介绍大面积GPS控制网在平差时应选用的方法。     

关于GPS网平面基准点的兼容性检验

GPS控制网在起算点包含粗差或错误的情况下,会导致GPS相对网形产生严重的扭曲和变形。因此,在约束平差前,必须对已知点的可靠性、兼容性进行检验分析,认为确实没有粗差或错误,方可用于约束平差。本文提出根据同一投影面上基准点间的相似变换关系,来检验GPS网平面基准点的可靠性、兼容性的方法。此法对于GPS网中只有2个基准点的情况也可判断其兼容性。     

专题图件面积量测中精度与平差问题初探——日产KP-80N型求积仪为量测工具

笔者根据量测1:1×10~5阿克苏河流域土地利用图的实验数据,从量测技术和被测图幅本身特点入手,探讨了它们与精度的关系.图斑面积量测误差主要与图斑的周长/单位面积值有关,并阐述了依其平差的科学性及按图斑面积比例平差的不合理性.     

GPS数据处理与平差软件对比分析

在实际生产过程中,很多生产单位选购了不同品牌的GPS接收机,在不同品牌接收机联合作业时,如何选择平差软件困扰着技术人员。为帮助工程人员应对日常GPS测量数据平差处理和选择相应处理软件,本文作者通过介绍GPS测量数据处理的一般流程,然后利用具体工程案例,对比分析了4种GPS平差软件(包括两款国内软件和两款国外软件)在软件性能、数学模型、基线处理和网平差结果方面的优劣。经对比,国产GPS平差软件更能符合我国相应测量规范的格式要求。应对不同等级控制网,在短基线处理时,各种GPS平差软件处理结果均能达到相应精度要求;在中长基线处理时,Pinnacle和HDS2003的误差模型和改正模型较多,解算精度较高,而Solution的自动化程度相对较低,但在基线处理中有一定优势。     

南极测绘中小像幅航片的区域网平差

本文介绍了用日产 Bronika SQ- A1 2 0型非量测相机对东南极拉斯曼丘陵 1 :40 0 0 0摄影比例尺小像幅航片进行加密的情况。通过用武汉测绘科技大学研制的联合平差程序 Wu CAPS软件的带附加参数的光束法区域网平差获得了实地上平面± 2 .82 9m,高程± 4.973 m的加密精度。文中还分析了若干精度问题 ,所得结论对今后的进一步研究将有所裨益     

摄影测量三维重建中多源信息融合方法探讨

分析摄影测量三维重建中不同数据源的特点,针对现有多源数据融合存在的有限数据源低层次融合问题,提出一种基于影像特征、GIS信息和3D TIN模型融合的层次结构与算法流程 .该算法主要包括多边形区域增长、几何推理和建筑物几何模型平差等处理,为基于摄影测 量的三维城市模型自动重建提供了一种新的思路与方法.     

大地水准面精化成果在航外控制测量的应用

本文通过在1∶1万航测外业基础测绘中应用已建区域精化似大地水准面模型测量像控点工作,从控制点使用数量、分布和达到的预期精度方面进行了试验。认为,一个大型的GPS网中使用3个点位可靠的B级点来约束GPS网平差,并配合精化似大地水准面插值模型取得的控制点坐标和高程,完全能够满足1∶10000甚至更大比例尺地形测量精度要求。为确保GPS网点拟合高程的可靠性,可适当用GPS联测国家水准点以检查GPS网点的高程拟合外符合精度。原有的国家三角点成果,由于测量年代悠久、历史原因和受当时的技术设备条件限制,其可靠程度和精度已不能用来检测和衡量GPS网点的平面和高程外符合精度。使用B级点来约束GPS网平差,并配合精化似大地水准面插值模型取得控制点坐标和高程,可以缩短工作周期,减少人员设备投入,降低成本消耗。     

基于PBBA的UltraCam数码航摄资料解析空三关键问题探讨

用传统的航摄资料生产大比例尺地形图,外业像控需全野外布点,现今数码航摄像机获取的数字影像资料已日益取代常规的航摄胶片资料,成为测绘行业的主流产品。本文基于光束法区域网平差软件PBBA,探讨UltraCam数码航摄资料在解析空三中的几个关键问题,通过试验,提出大比例尺地形图合理的外业像控点布设方案以及平差过程中的精度参数设置,大大地减轻了外业工作量,提高了工作效率,为大规模的采用数字航摄资料进行测绘生产奠定基础。     

用GPS技术监测南极半岛地区形变的结果初步分析

“全南极 GPS国际联测”已经进行了 6期观测。我们选取了位于西南极乔治王岛地区的 7个 GPS站 ,并加入 2个 IGS站 ,分别对 1 995、1 996、1 998年的同期 (GPS年积日 0 2 0 - 0 4 0 )观测数据进行了基线处理 ,相对精度可达 1 0 - 8- 1 0 - 9。并对 GAMIT软件解算得到的松弛解和强约束解分别进行了网平差处理 ,结果证明该地区比较稳定 ,总体上有 1 0 mm/a左右向西南方向的运动趋势。     

中国南极长城站测绘基准系统的建立

经1985年12月～1987年3月,三年度夏测绘科学考察,在中国南极长城站地区建立了一套完整的、精确的测绘基准系统。它包括大地坐标系统、高程系统和重力参考系统。本文叙述了建立这些基准系统的方法和数学模型,并分析了测量精度。     

A COMPARATIVE STUDY ON THE CARTOGRAPHIC HISTORIES BETWEEN CHINA AND THE WEST

Accrdingtothetertualresearchbyscholars,therehavebeenpatemcharts4o,oooyearsago.ThepotterymapsmadebytheBabyloniansthe26thcenturyB.C.havebeenwellpreservedtodayInChina,BaZhenandJiuDingaretheeariieStmaps.Atthattime,thepnmitivemeasunngtoolswereyardsticks,cords,dividersandrules.ThereisanaccoUntofmapin.theearlyZhouLi-DiGuan-T1lXun.Theterm"map"inEnglishisnotaptlyworded.asitmeansmap,skychartandStarchart.TheRussianword"Kapta"meansmap,piCtureandcard.ThemainmearungispiCtureandcard.Thispaperfocus…     

Local and regional components of western Aegean deformation extracted from 100 years of geodetic displacement measurements

Our objectives are as follows. First, we wish to develop a methodology to recover the long-term component of deformation from any set of distributed, time-averaged geodetic strain measurements that were subject to seismic disturbance, given a catalogue of local seismicity that occurred during the measurement period. Second, using seismic and geodetic data sets that span approximately 100 years, we apply this technique in the western Aegean to assess the role of local seismicity in regional deformation. The methodology is developed using a model for crustal deformation constructed from a long-term, smooth regional strain field combined with instantaneous, local perturbations from upper-crustal earthquakes approximated by static elastic dislocations. By inverting geodetic displacements for the smooth field while simultaneously floating influential but uncertain earthquake source parameters, an estimate of the regional component of deformation that is approximately independent of the seismicity can be made. In the western Aegean we find that the horizontal component of regional deformation can be described with minor inaccuracy by a quadratic relative displacement field. The principal horizontal extensional axes calculated from the regionally smooth displacement field agree in orientation with the T-axes of earthquakes in the region. These observations indicate that the instantaneous elastic strain of the 10 km thick seismogenic layer is driven by a stress field that is smooth on the scale of the geodetic network as a whole, 200-300 km.     

Relation between deformation and seismicity in the active fault zone of Kamchatka, Russia

In the regional geodetic network of the Russian Far East, an active fault zone of the Kamchatka peninsula has been selected in order to study the relation between seismic activity and deformation. This paper provides the first results of a detailed and high-precision 3-km long levelling profile, along which geodetic data have been collected weekly for almost three years. The data processing and analytical methods that were originally used have been elaborated for this particular type of very small local network. In the active fault zone, two distinct ways of releasing accumulated potential energy, i.e. seismicity and 'fault superintensive movements', have been registered. The inverse correlation that is discovered between deformation rate and seismic activity could be useful in earthquake forecasts.     

Data processing and analysis of crustal deformation monitoring in the Fildes region,West Antarctica

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西南极菲尔德斯半岛地壳形变监测的数据处理与分析

为了研究南极现代地壳运动,中国在西南极菲尔德斯海峡地区布设了形变监测网,并用ＤＩ－２０测距仪和ＧＰＳ定位仪对该网进行了监测。同时,中国也参加了ＳＣＡＲ组织的全南极ＧＰＳ联测。本文讨论了将形变参数纳入误差方程的水平形变数据处理方法,并对刚体平移、旋转、均匀应变几种典型形变模型在测边网平差中的运用进行了讨论。通过对经典自由网与秩亏自由网的基准分析,提出对形变参数以及其它附加参数和点位参数分别给定参考基准的方法。相应于上述方法,编制了一系列数据处理程序并将之应用于对西南极菲尔德斯海峡形变监测网的数据分析。本文还利用监测网应变分析原理,对ＧＰＳ监测数据进行了讨论和分析,结果表明,菲尔德斯断裂地区存在微小的断裂剪切运动,但位移量不大。     

差分GPS在乌拉特后旗1:25万区域重力调查中的应用

测地工作精度的高低直接影响着重力测量的精度,研究并采取行之有效的测地方法来配合重力测量工作是十分必要的。乌拉特后旗1:25万区域重力调查GPS测地工作采用1954年北京坐标系,重力测点平面位置、正常高采用差分GPS测量方法。结果表明,采用此方法既能满足技术要求,又达到了省时省力,且达到了重力测量的精度要求。     

On the consistency of earthquake moment release and space geodetic strain rates: Europe

In this paper, approximately 100 VLBI/SLR/GPS velocities map European strain rates from <0.09 × 10⁻⁸ to >9.0 × 10⁻⁸ yr⁻¹ with regional uncertainties of 20 to 40 per cent. Kostrov's formula translates these strain-rate values into regional geodetic moment rates M¯˙ _geodetic . Two other moment rates, M¯˙ _seismic , extracted from a 100-year historical catalogue and M¯˙ _plate , taken from plate-tectonic models, contrast the geodetic rates. In Mediterranean Europe, the ratios of M¯˙ _seismic to M¯˙ _geodetic are between 0.50 and 0.71. In Turkey the ratio falls to 0.22. Although aseismic deformation may contribute to the earthquake deficit ( M¯˙ _seismic values less than M¯˙ _geodetic ), the evidence is not compelling because the magnitudes of the observed shortfalls coincide with the random variations expected in a 100-year catalogue. If the lack of aseismic deformation inferred from the 100-year catalogue holds true for longer periods, then much of Europe's strain budget would have to be accommodated by more frequent or larger earthquakes than have been experienced this century to raise the ratios of M¯˙ _seismic to M¯˙ _geodetic to unity. Improved geological fault data bases, longer historical earthquake catalogues, and densification of the continent's space geodetic network will clarify the roles of aseismic deformation versus statistical quiescence.     

Effects of mechanical layering on volcano deformation

The migration and accumulation of magma beneath volcanoes often causes surface displacements that can be measured by geodetic techniques. Usually, deformation signals are explained using models with uniform mechanical properties. In this paper, we study surface displacements due to magma chamber inflation, using heterogeneous finite element models. We first present a systematic analysis of the influence of mechanical layering, showing that the stiffness contrast significantly affects the entity and the pattern of vertical and radial displacements. Second, as an example we apply the models to interpret ground displacements at Darwin volcano (Galápagos Islands) as revealed by InSAR data in the period 1992–1998. The considered models suggest that geodetic data interpreted using homogeneous models leads to underestimation of the source depth and volume change. Thus, we propose correction factors for the source parameters estimated by homogeneous models, in order to consider a range of variation due to mechanical layering as analysed in this study. The effect of the mechanical heterogeneities affects the correct understanding of geodetic data and also influences the evaluation of a volcanic hazard potential.     

An existence theorem for absolute geodetic singularities

Summary. It is shown that disturbing masses can be found which can give locally rise in the external gravity field of a spherically symmetric earth to singularities both in geodetic and in gravity space coordinates; in this connection the concept of absolute geodetic singularities is introduced. It is also shown that the previous results hold independently of the mass of the disturbing body and for densities of the disturbing mass which can be lower than the mean Earth density. The connection between the geodetic singularity problem and the study and design of gravity gradient compensators for orbital experiments is put into light.