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关于《电子速测仪坐标导线平差计算方法》的讨论 总被引：2，自引：0，他引：2
1999年第5期《测绘通报》刊载了《电子速测仪坐标导线平差计算方法》(以下简称《方法》)一文，提出了一种直接利用实测坐标进行平差计算的方法。本文对该方法有不同见解，并提出了另一种平差计算方法，供参考。 一、几点讨论 1. 《方法》一文作者认为，其平差方法是将角度误差与边长误差综合考虑进行平差的，比普通简易平差(将角度误差与边长误差分别进行分配)更为合理。笔者认为这两者是不可以比较的。因为在电子速测仪导线中仅仅测算出了坐标闭合差Fx和Fy，并没有测算出方位角闭合差Fα，只有2个多余观测，也就只能列出2个条件方程式(即就是测算出了Fα，《方法》中也未考虑)。普通简易平差用于普通导线测量中，要测算出方位角闭合差Fα，有3个多余观测，即有3个条件方程式。显然普通简易平差是将方位角闭合差Fα和坐标闭合差Fx与Fy绝对分成两步进行的，但其平差结果的精度肯定要比《方法》平差结果的精度高。 相似文献
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电子速测仪坐标导线平差计算方法 总被引：2，自引：0，他引：2
本文对电子速测仪标导线计算进行研究,提出一种直接利用所测得的坐标进行平差计算的方法,并通过算例来验证这一平差方法的正确性与可行性。 相似文献
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本文在开发研究全站型电子速测仪的专用功能的基础上，结合工程测施工放样的若干应用，提出了一系列自由设站的高效，实用的测设方法。 相似文献
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地面控制测量工程一体化自动化系统的研究与实现 总被引：1，自引：0，他引：1
本文通过对ＧＰＳ和电子速测仪测量系统两种现代测量技术的对照，指出地面控制测量在一体化与自动化方面所存在的问题、产生的原因和解决的方法，介绍了作者所研制的地面控制测量作业及其数据处理一体化与自动化系统的系统设计、软硬件情况以及应用前景。 相似文献
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A synthetic Earth for use in geodesy 总被引：1，自引：0，他引：1
R. Haagmans 《Journal of Geodesy》2000,74(7-8):503-511
A synthetic Earth and its gravity field that can be represented at different resolutions for testing and comparing existing
and new methods used for global gravity-field determination are created. Both the boundary and boundary values of the gravity
potential can be generated. The approach chosen also allows observables to be generated at aircraft flight height or at satellite
altitude. The generation of the synthetic Earth shape (SES) and gravity-field quantities is based upon spherical harmonic
expansions of the isostatically compensated equivalent rock topography and the EGM96 global geopotential model. Spherical
harmonic models are developed for both the synthetic Earth topography (SET) and the synthetic Earth potential (SEP) up to
degree and order 2160 corresponding to a 5′×5′ resolution. Various sets of SET, SES and SEP with boundary geometry and boundary
values at different resolutions can be generated using low-pass filters applied to the expansions. The representation is achieved
in point sets based upon refined triangulation of a octahedral geometry projected onto the chosen reference ellipsoid. The
filter cut-offs relate to the sampling pattern in order to avoid aliasing effects. Examples of the SET and its gravity field
are shown for a resolution with a Nyquist sampling rate of 8.27 degrees.
Received: 6 August 1999 / Accepted: 26 April 2000 相似文献
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Traditionally Inertial Surveying Systems (ISS) are used for missions of30 km to 100 km length. Today, a new type ofISS application is emanating from an increased need for survey control densification in urban areas often in connection with
land information systems or cadastral surveys.
The accuracy requirements of urban surveys are usually high. The loss in accuracy caused by the coordinate transfer betweenIMU and ground marks is investigated and an offsetting system based on electronic tacheometers is proposed.
An offsetting system based on a Hewlett-PackardHP 3820A electronic tacheometer has been tested in Sydney (Australia) in connection with a vehicle mountedLITTON Auto-Surveyor SystemII. On missions over750 m (8 stations,25 minutes duration,3.5 minuteZUPT intervals, mean offset distances 9 metres) accuracies of37 mm (one sigma) in position and8 mm in elevation were achieved. Some improvements to theLITTON Auto-Surveyor SystemII are suggested which would improve the accuracies even further. 相似文献
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Four binary thematic maps with combinations of two spatial autocorrelation levels and two different class proportions are simulated to study their effect on the precision of accuracy measures from different sampling designs. A series of eleven sample sizes (from a minimum of 25 to a maximum of 1296) are simulated using three popular sampling designs, including simple random sampling (SRS), systematic sampling (SYS), and stratified random sampling (StrRS) on the four simulated maps. The conventional error matrix and related accuracy measures are calculated for each simulation, and the precision of different estimates of accuracy measures is compared among the three sampling designs.The selection of a particular sampling design and sample size depends on the spatial autocorrelation level, the class proportion difference, and the accuracy indices that a given application requires. In general, the class proportion difference has a greater impact on the performance of different sampling methods than the spatial autocorrelation level does on a map. For estimating the accuracy of individual classes, stratified sampling achieves better precision than SRS and SYS with smaller sample sizes, especially for estimating the small class. For estimating the overall accuracy, different sampling designs achieve very similar levels of precision with fewer samples. To achieve a better estimate of the kappa coefficient, stratified random sampling is recommended for use on a map with a high class proportion difference, while random sampling is preferred for a map with low spatial autocorrelation and a low class proportion difference. 相似文献
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地图扫描数字化的点位精度分析 总被引：21，自引：0，他引：21
地图扫描数字化为建立ＧＩＳ提供了一种较好的原始地图数据获取方法，本文讨论了影响地图扫描数字化精度的诸种因素，分析了定向点和采样点误差对地图数字化结果的影响，发展了定向点和采样点的自动对中算法，从而保证地图扫描数字化的精度能满足建立ＧＩＳ的要求。 相似文献
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提出了一种面向土地覆盖变化信息局域精度评估的自适应型抽样策略。结合待研究地图的土地覆盖变化信息局部特征（如土地覆盖变化类别、斑块大小、异质性和优势度）,探讨与土地覆盖变化信息精度显著相关的协变量,以预测精度的标准误差作为判断标准,识别需要提高精度预测结果可靠性的区域,以自适应地和逐步定位的方式进行样本采集。基于武汉地区的精度评价结果,自适应的抽取增加100个训练样本使得预测精度的确定系数提高了50.66%,而简单随机抽取的增加样本使得预测精度的确定系数提高了17.22%。试验表明,自适应型抽样策略能显著提高土地覆盖变化信息局域精度预测的抽样效益,减少预测精度的不确定性。模型选择的结果表明,土地覆盖变化类别和优势度指数是最优的协变量组合。 相似文献
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随着全站仪的普及,极坐标法放样变得愈加简单。在放样过程中,利用误差传播定律对坐标放样精度进行分析,保证建筑物放样的精度,结合一定的操作手段及检核方法,使放样精度满足施工要求。 相似文献
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针对高楼林立的城区难以精确检测高层建筑物垂直度的特点，采用垂准仪与电子全站仪相结合进行垂直度检测，对检测精度进行了系统的分析，并以某高楼的垂直度实际检测进行了验证，充分说明该方法适应性强，作业简便，检测精度高且成果可靠。 相似文献