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采用GNSS手段建立大地控制网是目前工程应用中最为常见的一种形式。GNSS控制网数据处理过程主要包含预处理、基线解算及网平差过程,网平差时需要选择独立基线参与解算,独立基线选取质量高低直接影响最终结果精度。鉴于此,探讨独立基线的选取方法,分别采用顺序连接型、射线型、随机选择等方式选取独立基线参与网平差,并对不同方法选取的独立基线进行网平差后精度分析,为GNSS控制网独立基线选取提供了有益借鉴。 相似文献
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程少杰 《测绘与空间地理信息》2021,44(9):217-220,224
BASELINE和RELAX是GAMIT软件基线处理中两种不同的解算模式,为对比两种基线处理模式在高速铁路框架控制网数据处理结果,并确定何种基线处理模式更适用于高速铁路框架控制网的数据处理,应用BASE-LINE、RELAX基线处理模式进行基线处理,并采用TGPPS软件进行网平差,以均方根误差、基线重复性、基线较差、网平差等结果进行对比.结果表明,高速铁路长大干线的框架控制网基线解算中采用BASELINE效果较好. 相似文献
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基线向量是将全球导航卫星系统(GNSS)接收机采集的观测数据用随机软件、商用软件或者专用软件计算出来的接收机之间的三维坐标差,基线向量是相对定位的结果,他是控制网平差的观测量,基线向量的质量影响着控制网的平差结果,控制网在无约束平差以及约束平差前应对基线向量进行质量检验,检验的目的是为了剔除粗差以及基线解超限的基线,通过对某C级网的计算发现,不进行基线检核的约束平差结果反而比进行基线检核的约束平差结果得到更高的点位精度,通过对点位中误差计算过程的分析,可以得出随着多余观测量的增加,在不进行基线检核的情况下反而会得到虚高的点位中误差,GNSS控制网的点位中误差并不能完全真实反映控制网的精度,而单位权中误差的大小更能反映网的精度,因此GNSS控制网在无约束以及约束平差前进行基线检核很有必要。 相似文献
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概述了GNSS数据处理的流程,详细讨论了GNSS基线向量网不同类型平差的数学模型、算法设计和软件实现方法,设计开发了高精度GNSS基线向量网平差软件。所设计的软件能够完成最小二乘平差、秩亏自由网平差、稳健估计、拟稳平差、粗差探测等计算,软件还添加了绘图界面,可以显示和操作三维控制网图。并通过实例验证了软件的准确性和实用性。 相似文献
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高精度GPS基线向量网平差 总被引:9,自引:0,他引:9
系统地论述了利用基线向量作为虚拟观测量进行平差的基本原理,着重对双因子抗差估计、系统参数求解、方差分量估计等在GPS基线网平差中的应用进行了分析,最后简单介绍了基线向量网平差软件GPSADJ。 相似文献
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关于高精度GPS网平差基本观测量的选取问题 总被引:13,自引:0,他引:13
由各同步图形的观测基线上向量构成的GPS网,平差时就如何选取这些基本观测参与平差,不同方式和数量上的选取是否会影响结果,尚存在不同看法,本文从理论上进行证论并提出看法。 相似文献
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介绍了超站仪在既有线普速铁路平面控制网中的测量和数据处理流程,提出了采用超站仪进行测量的方向值、平距两类地面观测值和解算后的基线向量进行联合平差计算方法,并推导了该方法在既有线普速铁路轨道平面控制网平差应用中的模型.通过采用该方法对某实测控制网进行联合平差处理,表明其处理结果可满足对应控制网等级的内业平差精度要求,且能... 相似文献
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各民族、各国家的区域范围在不同的发展时期大小不一。本文提出了基于Silverlight的区域变迁演示系统设计,以江东六十四屯区域演变为例,基于Silverlight,Bing Maps,Sql Server,Visual Studio.NET等关键技术与软件平台,将历史、地理知识与测绘地理信息高度结合,设计出表现力丰富、交互能力强的区域变迁演示系统,实现让单一的历史地图以生动活泼的新面貌向世人展示等功能。 相似文献
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随着科学技术的发展,测量工具和测量手段也发生了变化,其中测量型GNSS呈现价格降低、体积缩小的趋势。目前市场上一整套商用GNSS测量系统的价格从几万到几十万不等,且由于地面基站和移动站体积大、携带不方便等原因,使得商用GNSS测量系统的使用人群仅限于部分专业测量人员,难以在大众市场普及。当今众多领域如无人机、机器制导、精密农业等对高精度定位需求的增加,又促使GNSS测量系统向低成本、高精度、小型化、轻型化发展。本文对U-BLOX的NEO-M8P低成本OEM型GNSS接收机进行50 km基线下的静态观测,基于RTKLIB的测试结果和精度分析表明,低成本GNSS测量系统能够达到厘米级定位精度,能够满足测量工作和GIS应用的需求。试验证明,使用此低成本测量系统能降低测量任务的经济成本,是测量级GNSS接收机中经济适用的选择。 相似文献
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G. Blaha 《Journal of Geodesy》1978,52(3):191-198
The radial distance (length of a position vector) from the geocenter to the geoid as defined by the spherical harmonic potential
coefficients is needed e.g. in the process of adjusting satellite altimeter data. The geocentric latitude and longitude associated
with this distance are assumed known—in this case derived from satellite altimetry. Typically, the radial distance can be
computed to a desired accuracy in an iterative process. Even if a crude initial value is adopted, a sub-meter accuracy is
achieved on the second iteration, while the third iteration yields a sub-millimeter accuracy. If the best possible initial
value is taken, such as the radial distance to the mean earth ellipsoid, the iterative process may be accelerated by one iteration.
But even then two iterations will be needed in most cases. However, an algorithm has been designed that yields excellent results,
characterized by a sub-centimeter accuracy, already from the first iteration. It results in important computer savings, considering
that in real data reductions of satellite altimetry, the radial distance needs to be computed at thousands of locations. 相似文献
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“轻终端+行业云”的实时北斗滑坡监测技术 总被引:1,自引:1,他引:0
对滑坡区域进行地表高精度实时三维变形监测,是实现滑坡灾害精准预警的前提。GNSS技术是目前唯一直接获取滑坡灾害实时地表三维矢量变形的手段,但GNSS应用于大范围滑坡监测存在成本高和计算能力差两大问题。本文采用物联网思维,以"云+端"的设计理念,自主研发了千元级小型化实时北斗/GNSS监测技术装备,并研制了毫米级实时监测预警云平台,成果成功应用于甘肃黑方台滑坡实时监测预警。联合成都理工大学预警系统提前40 min发出了准确预警信号,避免了人员伤亡和财产损失。安装在滑坡体上的远程视频监控首次近距离记录了滑坡灾害发生的全过程。 相似文献
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《International Journal of Digital Earth》2013,6(1):65-77
Abstract Collision detection is an important component in simulation applications which are based on virtual geographic information system (VGIS). In this paper, an effective collision detection algorithm for multiple objects in VGIS, VGIS-COLLIDE, is presented. The algorithm firstly integrates existing quadtree, which is the global hierarchical structure of VGIS, with axis-aligned bounding box of object to perform the broad-phase of collision detection. After that, exact collision detection between two objects which have passed the broad-phase of collision detection is performed. The algorithm makes no assumption about input primitives or object's motion and is directly applicable to all triangulated models. It can be applicable to both rigid and deformable objects without preprocessing. The performance of the algorithm has been demonstrated in several environments consisting of a high number of objects with hundreds of thousands of triangles. 相似文献
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Jan-Michael Frahm Marc Pollefeys Svetlana Lazebnik David Gallup Brian Clipp Rahul Raguram Changchang Wu Christopher Zach Tim Johnson 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(6):538-549
This paper presents a system approaching fully automatic 3D modeling of large-scale environments. Our system takes as input either a video stream or collection of photographs obtained from Internet photo sharing web-sites such as Flickr. The system achieves high computational performance through algorithmic optimizations for efficient robust estimation, the use of image-based recognition for efficient grouping of similar images, and two-stage stereo estimation for video streams that reduces the computational cost while maintaining competitive modeling results. In addition to algorithmic advances, we achieve a major improvement in computational speed through parallelization and execution on commodity graphics hardware. These improvements lead to real-time video processing and to reconstruction from tens of thousands of images within the span of a day on a single commodity computer. We demonstrate modeling results on a variety of real-world video sequences and photo collections. 相似文献
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黄河防洪遥感应用试验简介 总被引:1,自引:0,他引:1
本文详细地介绍了1988年黄河防汛遥感试验的情况,着重介绍了遥感图像、水位数据实时传 输系统的建立及试验的结果,介绍了黄河试验区防洪数据库的建立及试验取得的成果以及利用极 轨气象卫星进行洪水监测的结果。 相似文献
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none 《The Cartographic journal》2013,50(2):91-92
AbstractA reconstruction is made of the methods by which the Ordnance Survey of Great Britain pioneered a system for establishing the place-name nomenclature on its maps in the nineteenth century. Until 1820 there was little to differentiate the practice of the Survey from that of earlier cartographers but, thereafter, official surveyors were encouraged to consult a wide range of written and oral authorities and were instructed to record their findings in special name books. By the mid-nineteenth century the essentials of the modern system had been laid down and many thousands of local names published in map form for the first time.This paper was read in a shorter form to the annual symposium of the Society in September 1970, at the University of Bristol. 相似文献