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Ernst Heinrich Knickmeyer 《Journal of Geodesy》1994,68(2):71-76
The inspection of a pipeline from the inside becomes more and more widespread. An inspection tool, called Geometry Pig, carries a variety of sensors, among which a strapdown inertial system provides essential geometric information on the pipeline. In this paper the inspection pig is described as a surveying tool, which delivers information on centre line, shape and features of the pipe. After some background information it is explained, why the inertial system is the optimal instrument to deliver some structural parameters of the pipeline. The interaction between data evaluation and measurement procedure is discussed in view of the very few possibilities to vary the procedure. One of them is a forced rotation about the forward axis. Analogies are shown to traditional surveying procedures. Finally some results of actual surveys are presented. A positioning accuracy of 1:2500 is achieved with respect to tie points. 相似文献
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叶绿素a荧光遥感研究进展 总被引：11，自引：0，他引：11
继叶绿素a反演的“蓝绿比值法”后,叶绿素a荧光遥感成为海水叶绿素a浓度反演的重要方法,对提高二类水体和赤潮水体的叶绿素a浓度的反演精度效果明显。本文回顾了人们对水体叶绿素a荧光的认识、测量和研究的历史过程,介绍了荧光产生的生物学机理以及它随叶绿素a浓度的正相关和“红移现象”等主要光谱特征。本文还总结了荧光量子产量、不同藻种生理状态、水体其他物质及大气的吸收等多种因素对叶绿素a荧光遥感的影响。基于对叶绿素a荧光光谱特征和影响因素的认识,人们相继建立了两种荧光遥感方法———基线荧光高度法和归一化荧光高度法。对于前景广阔的叶绿素荧光遥感领域,人们正进行着更深入的研究与探索,积累更多的现场数据和卫星同步数据,逐步完善和改进反演模型。 相似文献
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H. Kutterer 《Journal of Geodesy》1998,72(2):51-63
GPS has become an essential tool for the precise determination of point positions. Since GPS campaigns for geodynamic purposes
– such as the monitoring of recent crustal movements – require major financial efforts, it is essential to ensure already
in the planning phase a good network quality and the attainment of the scientific goals in a reasonable time. The paper outlines
an operationally oriented procedure for these purposes based on the simulation and processing of GPS carrier-phase observations.
Sensitivity analysis techniques are applied to describe both the network strain as it may be induced by gross errors and the
detectability of point movements between two sessions or two campaigns. In addition, the eigenvalue decomposition of the variance-covariance
matrix of the GPS coordinates will be used to identify weakly determined network components. The design of the SCAR Epoch
95 Campaign GPS network is discussed throughout the paper. It was realized in the Antarctic summer 1994/1995 on the Antarctic
peninsula.
Received: 30 November 1995 / Accepted: 1 July 1997 相似文献
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Giuseppe Birardi 《Journal of Geodesy》1993,67(4):201-209
Some time ago it was agreed to set up a European GPS Traverse from Tromsö (Norway) to Syracuse (Sicily), to improve the definition of the European geoid.An outline of the Italian portion of this Traverse is summarized here, with special reference to the sections from the Brenner Pass to Taranto — carried out in 1989 — and for those from Taranto to Syracuse-Noto, recently completed.The observing procedures and results are reported here. A comparison with the results of the ITALGEO '90 geoid, and a tentative profile of the Italian geoid along the whole traverse are also sketched.Furthermore, a net of similar traverses, a first order geoidal net in Italy is proposed, in order to support the existing and new geoid determinations. In such a way a sub-decimetric accuracy in the Italian GPS derived orthometric heights may probably be achievedPaper presented at the XVII General Assembly of the IUGG Vienna, 12–23 August 1991 相似文献
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Sam Amirebrahimi Abbas Rajabifard Priyan Mendis Tuan Ngo 《International Journal of Digital Earth》2016,9(4):363-386
Flood damage assessment (FDA) is a key component of risk-based method for flood management. In the current FDA approaches, generally the uniqueness of the building is disregarded in the analysis. Therefore, they are unfit for detailed applications in which case-by-case analysis of building damage is an essential requirement. This limitation is compounded by the use of incomplete and often low-quality data inputs about the building and the assumptions and approximations made regarding the geometry and materials of its components. Such shortcomings may result in incomplete and uncertain outcomes. Considering the benefits and increasing use of three-dimensional (3D) urban modeling and Building Information Model in various urban management processes, in this paper, an integrated framework for utilization of detailed 3D building models for the assessment and 3D visualization of flood damage to building according to its distinct behavior against flood is presented. A proof-of-concept demonstration of the framework in a case study underlined the feasibility of implementation of the framework, which can potentially benefit a variety of users and be used as a complementary approach to the current FDA methods for improving the resilience of the community toward floods and their adverse impacts. 相似文献
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Glyphs are small geometric shapes that in geovisualization are often used to represent multidimensional spatial data. The aim of this study is to investigate the effectiveness of their two types – star and polyline glyphs, as they can encode the same message and can provide similar functionality. Thus, if the two glyph types are similar and can be used for the same data, the question arises as to which of them better facilitates various user tasks. To address this question, an empirical study of 26 individual users is conducted to investigate differences in user performance for polyline and star glyphs shown either in a grid plot or on a map display. In this study, a task-based approach with eye-tracking is applied, as well as a subjective questionnaire and a psychological test of cognitive style. The finding is that polyline glyphs better facilitate tasks when datapoint values in glyphs are to be read, whereas star glyphs are better when a visual search among glyphs is to be done. Moreover, the results reveal that the map display works better than the grid plot. If star glyphs are to be used, the key (legend) needs to be better incorporated into a visual interface. 相似文献
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利用MODIS影像数据,对水华现象出现的重要物质——巢湖水体叶绿素a信息进行反演。在对数据进行预处理后,采集影像相应位置的像元灰度值,与现实中在对应位置观测的湖水叶绿素a浓度进行相关性拟合分析,得到叶绿素a浓度与像元灰度值的相关性方程与相关系数。在建立相关性模型时采用了单波段和波段比值法,得到的最高相关系数为R2=0.881 8,表明利用这种方法反演巢湖水体叶绿素a浓度空间分布具有一定的可靠性。选择相关系数性较高的2个拟合方程反向演算MODIS影像,最后成功得到巢湖湖面当日叶绿素a浓度分布状况图,为巢湖防治水华发生提供了比较准确可靠的信息。 相似文献
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以武汉东湖为研究区域,利用MODIS数据和地面准同步叶绿素a浓度实测数据,建立适合东湖水体的叶绿素a浓度遥感定量估算模型,从而分析MODIS数据应用于内陆湖泊水体叶绿素a浓度反演的可行性。 相似文献
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针对利用遥感数据进行土地荒漠化分析研究的角度单一问题,提出一种从土地生产力和植被长势两个角度进行土地荒漠化时空变化分析的方法。通过研究新疆13 a 4—10月期间的植被降水利用率和植被覆盖度的时空变化特征综合反映新疆13 a土地荒漠化的演变情况。研究结果表明,新疆土地生产力较好、植被退化的区域约占新疆国土面积的9.32%,土地生产力较差、植被退化的区域约占0.02%,土地生产力较差、植被恢复的区域约占1.37%;土地生产力正常、植被恢复的区域约占89.29%;在植被生长的不同时期,降水量对土地荒漠化的正面抑制作用呈现增强、不变或减弱的特征。研究结果,可为土地荒漠化评价方法的研究提供理论参考。 相似文献
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Journal of Geographical Systems - Time geography was conceptualized in the 1960s when the technology was very different from what we have today. Conventional time-geographic concepts therefore were... 相似文献
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《International Journal of Digital Earth》2013,6(4):404-425
Abstract The emergence of Cloud Computing technologies brings a new information infrastructure to users. Providing geoprocessing functions in Cloud Computing platforms can bring scalable, on-demand, and cost–effective geoprocessing services to geospatial users. This paper provides a comparative analysis of geoprocessing in Cloud Computing platforms – Microsoft Windows Azure and Google App Engine. The analysis compares differences in the data storage, architecture model, and development environment based on the experience to develop geoprocessing services in the two Cloud Computing platforms; emphasizes the importance of virtualization; recommends applications of hybrid geoprocessing Clouds, and suggests an interoperable solution on geoprocessing Cloud services. The comparison allows one to selectively utilize Cloud Computing platforms or hybrid Cloud pattern, once it is understood that the current development of geoprocessing Cloud services is restricted to specific Cloud Computing platforms with certain kinds of technologies. The performance evaluation is also performed over geoprocessing services deployed in public Cloud platforms. The tested services are developed using geoprocessing algorithms from different vendors, GeoSurf and Java Topology Suite. The evaluation results provide a valuable reference on providing elastic and cost-effective geoprocessing Cloud services. 相似文献
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《测绘科学》2020,(9)
针对利用遥感数据进行土地荒漠化分析研究的角度单一问题,提出一种从土地生产力和植被长势两个角度进行土地荒漠化时空变化分析的方法。通过研究新疆13 a 4—10月期间的植被降水利用率和植被覆盖度的时空变化特征综合反映新疆13 a土地荒漠化的演变情况。研究结果表明,新疆土地生产力较好、植被退化的区域约占新疆国土面积的9.32%,土地生产力较差、植被退化的区域约占0.02%,土地生产力较差、植被恢复的区域约占1.37%;土地生产力正常、植被恢复的区域约占89.29%;在植被生长的不同时期,降水量对土地荒漠化的正面抑制作用呈现增强、不变或减弱的特征。研究结果,可为土地荒漠化评价方法的研究提供理论参考。 相似文献
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应用MODIS数据反演河北省海域叶绿素a浓度 总被引：6，自引：0，他引：6
为了建立更加合理、准确的叶绿素a遥感反演模型,利用地物光谱仪测定了河北省海域水面的光谱反射率,分析了光谱反射率与实测叶绿素a浓度之间的关系.在此基础上,通过MODIS数据各波段及波段组合的反射率与实测叶绿素a浓度的相关分析,确定第1波段(B1)为最佳反演波段,建立了应用B1反演叶绿素a浓度的遥感模型,并对模型精度进行验证.结果表明:该模型相关系数为0.66,反演结果均方根误差为0.48 mg/m3,模型精度优于SeaDAS的OC3标准经验算法;该模型反演河北省海域表层水体的叶绿素a浓度有较好的效果. 相似文献
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《测绘科学》2021,(9)
针对利用遥感数据进行土地荒漠化分析研究的角度单一问题,提出一种从土地生产力和植被长势两个角度进行土地荒漠化时空变化分析的方法。通过研究新疆13 a 4—10月期间的植被降水利用率和植被覆盖度的时空变化特征综合反映新疆13 a土地荒漠化的演变情况。研究结果表明,新疆土地生产力较好、植被退化的区域约占新疆国土面积的9.32%,土地生产力较差、植被退化的区域约占0.02%,土地生产力较差、植被恢复的区域约占1.37%;土地生产力正常、植被恢复的区域约占89.29%;在植被生长的不同时期,降水量对土地荒漠化的正面抑制作用呈现增强、不变或减弱的特征。研究结果,可为土地荒漠化评价方法的研究提供理论参考。 相似文献
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Rotation of the Earth as a Triaxial Rigid Body 总被引：2，自引：6，他引：2
SHEN Wenbin CHEN Wei WANG Wenjun LIANG Yiqiang 《地球空间信息科学学报》2007,10(2):85-90
The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated. 相似文献
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YU Jie Ursula Pietrzak Jim Peterson 《地球空间信息科学学报》2005,8(4):257-261
In that orcharding in early-to-mid twentieth century southeastern Australia involved use of certain heavy metal and As compounds in regular pest-control spray procedures, some interest attaches to the possibility that these landparcels are underlain by soils with above-background Cu, Pb and As levels. Interpreta- tion of Land-cover changes allowed land parcels previously occupied by orchards to be identified in the 1950s through time-series air-photos. A comparison of soil analysis results referring to soil samples from control sites, and from land parcels formerly occupied by orchardists, shows that contamination （above-background） levels of cations in the pesticides can be found in the top 6 cm of former orchard soils. It is clear that digital spatial data handling and culturally-informed air photo interpretation has a place in soil contamination studies, land-use planning （with particular reference to re-development） and in administration of public health. 相似文献