共查询到20条相似文献，搜索用时 78 毫秒
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本文通过引入等量坐标概念，讨论高斯坐标和等量坐标以及大地坐标之间的关系，推导高斯投影坐标正反算的递推算法公式。 相似文献
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本文通过对地图学和计算机辅助教学的介绍,提出了在地图学各课程的教学过程中应用计算机进行辅助教学的必要性,并在地图的数学基础这一部分进行试验研究,证明了地图学计算机辅助教学的可行性,构筑了地图学计算机辅助教学的框架。 相似文献
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空间地理信息数据在"北京54坐标系"与"西安80坐标系"之间的相互转换方法 总被引：1，自引：0，他引：1
在地理信息系统建设过程中,由于数据源的多样性造成的坐标系统的转换是经常性的。本文是作者在多年空间地理信息数据处理实践中总结出来的新旧坐标系转换的方法,并涉及矢量数据和影像数据。 相似文献
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本文研究了墨卡托投影坐标在中国所用老的（克拉索夫斯基）和新的（ＩＡＧ－７５）两种精球的情况。作者分析了两者之间的差别，得出其间的误差为土０．０１ｃｍ以内，即在制图容差之内。故结论是，当在两个棉球之间作变换时，可毋需修正。 相似文献
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GPS坐标转换中高程异常误差影响规律研究 总被引：9，自引：0，他引：9
针对GPS坐标转换中利用公共点求转换参数，推导了由含有较大误差的高程异常值获得的大地高误差对坐标转换参数的影响，以及由此对转换坐标的影响的有关公式。并利用这些公式分别计算研究了在我国不同区域高程异常误差对坐标转换的影响规律，提出了一些有益结论。 相似文献
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高精度地面点位置的三维地心坐标和板块运动 总被引：2，自引：0，他引：2
高精度确定地面点三维地心坐标时，一是要考虑它所采用坐标系的定义，二是要顾及地球动力现象对其点位坐标的影响。本文对世界上若干通用的三维地心坐标系及其相互关系和涉及板块运动对点位的影响作一介绍。 相似文献
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工业三维坐标测量系统的最新进展 总被引：5，自引：0，他引：5
工业测量是指在制造工业和机器安装工业中，对部件和产品的形体进行精密的三维坐标测量。工业测量系统是指以电子经纬仪、全站仪、数字相机等为传感器，在计算机的控制下，完成工件的非接触和实时三维坐标测量，并在现场进行测量数据的处理、分析和管理的系统。与传统的工... 相似文献
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建立过渡坐标系进行平面坐标系统相互转换的研究 总被引：2，自引：3，他引：2
分析了平面坐标系统相互转换数学模型中尺度因子的可变性，针对建立地方独立坐标系统的特点，提出了一种建立过渡坐标系来改变尺度因子可变性的坐标转换方法。 相似文献
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图形数字化即是将既有图形信息转换成数字式的数据，并将这些数据以文件的形式存放在计算机里，以便数据库管理和绘图程序调用。本文介绍了一个图形系统（ＧＤＳ），它除具有直接取点数字化的功能外，还具有坐标定位与转换数字化、图形显示与绘制、图形数据显示与打印及多边形面积与周长计算等功能。 相似文献
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王丽明 《测绘与空间地理信息》2002,25(2):10-11
主要研究地图的艺术性 ,为使广大读者对地图的艺术性有一个全面的了解和认识 ,主要从以下三方面进行论述 :①地图的艺术性在现代地图发展中的重要意义 ;②地图艺术性的表现形式 ;③地图艺术性的形式及其发展趋势 相似文献
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在简要介绍了WebGIS主要实现模式和ArcIMS体系结构基础上,重点论述了基于ArcIMS的校园WebGIS系统平台的构建,实现了具有基本地图编辑、查询、图层操作与3维仿真显示等功能的内蒙古师范大学校园地理信息的网上发布,若能继续完善并与我校目前＂数字校园＂建设的显著成果相结合,对促进内蒙古师范大学＂数字校园＂工程的... 相似文献
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The defense meteorological satellite program (DMSP) operational linescan system (OLS) sensors have imaged emitted light from Earth's surface since the 1970s. Temporal overlap in the missions of 5 OLS sensors allows for intercalibration of the annual composites over the past 19 years (Elvidge et al., 2009). The resulting image time series captures a spatiotemporal signature of the growth and evolution of lighted human settlements and development. We use empirical orthogonal function (EOF) analysis and the temporal feature space to characterize and quantify patterns of temporal change in stable night light brightness and spatial extent since 1992. Temporal EOF analysis provides a statistical basis for representing spatially abundant temporal patterns in the image time series as uncorrelated vectors of brightness as a function of time from 1992 to 2009. The variance partition of the eigenvalue spectrum combined with temporal structure of the EOFs and spatial structure of the PCs provides a basis for distinguishing between deterministic multi-year trends and stochastic year-to-year variance. The low order EOFs and principal components (PC) space together discriminate both earlier (1990s) and later (2000s) increases and decreases in brightness. Inverse transformation of these low order dimensions reduces stochastic variance sufficiently so that tri-temporal composites depict potentially deterministic decadal trends. The most pronounced changes occur in Asia. At critical brightness threshold we find an 18% increase in the number of spatially distinct lights and an 80% increase in lighted area in southern and eastern Asia between 1992 and 2009. During this time both China and India experienced a ∼20% increase in number of lights and a ∼270% increase in lighted area – although the timing of the increase is later in China than in India. Throughout Asia a variety of different patterns of brightness increase are apparent in tri-temporal brightness composites – as well as some conspicuous areas of apparently decreasing background luminance and, in many places, intermittent light suggesting development of infrastructure rather than persistently lighted development. Vicarious validation using higher resolution Landsat imagery verifies multiple phases of urban growth in several cities as well as the consistent presence of low DN (<∼15) background luminance for many agricultural areas. Lights also allow us to quantify changes in the size distribution and connectedness of different intensities of development. Over a wide range of brightnesses, the size distributions of spatially contiguous lighted area are consistent with power laws with exponents near −1 as predicted by Zipf's Law for cities. However, the larger lighted segments are much larger than individual cities; they correspond to vast spatial networks of contiguous development (Small et al., 2011). 相似文献
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2009年武汉市植被净初级生产力估算 总被引：1，自引：0，他引：1
利用CASA模型,结合实测的光合有效辐射（PAR）数据、MODIS归一化植被指数（NDVI）和Land Cover数据、气象数据等资料,估算了2009年武汉市的植被净初级生产力（NPP）。结果显示,武汉市的植被平均单位面积年NPP产量达到464.19gC·m^-2·a^-1。6、7、8三个月NPP积累值最高,占全年的56.8%;12、1、2三个月NPP值最低,仅占5.6%。黄陂区由于林地较广,NPP值较大,在1 000gC·m^-2·a^-1以上;而城市周边由于植被覆盖面积较小,NPP值较低,在400gC·m^-2·a^-1以下。 相似文献
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本文以南京地铁一号线盾构三标(玄武门至南京站)为例,分析了线路中桩坐标计算程序的编写思路,阐述了根据里程(桩号)求坐标的方法。用计算机对隧道中心与线路中心坐标进行了计算,克服了手工计算缓和曲线及隧道中心与线路中心的偏移量上的繁杂。简化了工作量,保证了测量数据处理的准确与快速。 相似文献
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Anjali Bahuguna Shailesh Nayak Dam Roy 《International Journal of Applied Earth Observation and Geoinformation》2008,10(2):229-1
Tsunami waves struck the Indian coast on 26th December 2004 affecting the Andaman and Nicobar group of islands. A quick assessment of the status of the vital coastal ecosystems has been made using pre- and post-tsunami Advance Wide Field Sensor (AWiFS) data of Indian satellite RESOURCESAT with an accuracy of 87–90% and the Kappa ranging from 0.8696 to 0.9053. Among the coastal ecosystems the coral reefs have suffered the maximum with the Nicobar reefs (69% eroded and 29% degraded) bearing the brunt more than the Andaman reefs (54% eroded and 22% degraded). Significant improvement to the condition of the reef damaged due to backwash has been noted. About 41% of the Sentinel reef area has undergone significant improvement. The continuance of the erosion of the southwestern Andaman reefs is due to the impact of recurring earthquakes. The impact on mangroves of both the groups of islands has been due to uprooting as well as inundation of seawater and resulting stagnation. Changes are expected in community structure of mangroves as a result of tsunami. 相似文献
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Valérie Ballu Jérome Ammann Olivier Pot Olivier de Viron Glenn S. Sasagawa Gilles Reverdin Marie-Noelle Bouin Mathilde Cannat Christine Deplus Sébastien Deroussi Marcia Maia Michel Diament 《Journal of Geodesy》2009,83(2):147-159
Decades of cruise-based exploration have provided excellent snapshots of the structure of mid-ocean ridges and have revealed
that accretion is a mixture of steady-state and quantum events. Observatory-type studies are now needed to quantify the temporal
evolution of these systems. A multi-disciplinary seafloor observatory site is currently being set up at the Lucky Strike volcano,
in the axial valley of the slow spreading Mid-Atlantic ridge as a part of the MoMAR (monitoring of the Mid-Atlantic Ridge)
initiative. The aim of this observatory is to better understand the dynamics of the volcano and the hydrothermal vents hosted
at its summit as well as their plumbing systems. In August 2006, the GRAVILUCK cruise initiated an experiment to monitor the
deformation of Lucky Strike volcano. A geodetic network was installed, and seafloor pressure, gravity and magnetic data were
collected. In this paper, we present the method used to monitor volcanic deformation, which involves measuring relative depth
difference between points within a seafloor geodesy network. We show that, taking into account oceanographic variability and
measurement noise, the network should be able to detect vertical deformations of the order of 1 cm. 相似文献