共查询到20条相似文献，搜索用时 31 毫秒
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分析了球面Quaternary编码的特点，给出了三角格网方向判断的规则，并对该算法与Bartholdi邻近搜索算法的时间复杂度进行了对比。结果表明，分解算法的平均时间耗时量约是Bartholdi邻近搜索算法的23．66％。 相似文献
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The characteristic of Quaternary codes is analyzed. The rule of distinguishing triangle direction is given out. An algorithm of neighbor finding by decomposing the Quaternary code from back to front is presented in this paper. The contrastive analysis of time complexity between this algorithm and Bartholdi＇s algorithm is approached. The result illustrates that the average consumed time of this algorithm is about 23.66% of Bartholdi＇s algorithm. 相似文献
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P. V. L. P. Babu 《Journal of the Indian Society of Remote Sensing》1973,1(1-2):65-67
Morphostructure is a form of the earth’s relief, developed due to tectonic movements. Structures which have undergone movement in the Quaternary time are commonly recognised in areas of low relief and recent deposition. A number of morphpstructures are delineated through geomorphologlcal studies in the Krishna and the Godavari delta region of the coastal Andhra Pradesh which are likely to entrap oil and gas. The morphostructural trends are in confirmation with the known regional trends. 相似文献
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条件随机场模型约束下的遥感影像模糊C-均值聚类算法 总被引：2，自引：1，他引：1
遥感影像具有丰富的空间相关信息,而传统的基于像元光谱的聚类算法并不能将空间信息融入聚类,聚类结果往往不好。针对这一问题,本文提出了一种条件随机场模型约束下的模糊C-均值聚类算法,通过邻域像元的分类先验信息对中心像元的类别进行约束从而提取空间相关信息,基于二阶条件随机场将光谱信息和空间相关信息同时融入聚类,并使用环形置信度迭代算法得到像元分类后验概率的全局最优推测。试验证明,本文算法能够有效地保持地物的形状特征,分类精度相比传统算法有所提高。 相似文献
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GIS算法基础实验教学是引导学生透彻理解GIS算法原理,掌握GIS算法应用技术的重要环节。论文重点分析了GIS算法基础课程的内容特点,并结合笔者在GIS算法基础方面的教学经验,建立了以实验教学系统平台为基础和以算法功能设计为主体的教学内容体系,同时建立了以项目导向式为主的教学方法体系。 相似文献
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随着世界海洋经济的快速增长和各国海洋贸易的持续发展,船舶AIS系统被世界各国广泛采用,由此产生海量的船舶轨迹数据。如何对这些多维、动态的数据进行挖掘和利用,成为当前时空数据挖掘领域的研究热点之一。文中在经典DBSCAN空间聚类算法的基础上,对船舶轨迹数据进行清洗、压缩等预处理,并将其划分为特征点相连的子轨迹段,然后引入时间距离度量方法,实现对船舶轨迹的时空聚类。最后基于东海某海域(113°45′37″E~130°23′43″E,17°47′29″N~38°52′59″N)近一个月的船舶轨迹数据进行实验,结果表明相比经典DBSCAN算法,文中算法能够在兼顾时间信息的基础上,对船舶轨迹数据进行有效的时空聚类,为后续研究预测船舶的行为模式奠定基础。 相似文献
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面向对象的覆膜农田信息遥感表征方法 总被引：1，自引：0，他引：1
为解决复杂土地利用背景下覆膜农田信息遥感提取方法缺乏的问题,该文以河套灌区为研究区,以Sentinel-2A卫星数据为基础,结合面向对象影像分析和随机森林算法,开展了复杂土地利用背景下灌水与无灌水覆膜农田信息遥感同步提取研究。首先进行遥感影像尺度分割研究,优选出最佳分割尺度。在此基础上,提取光谱特征、纹理特征、几何特征,获取优化特征子集,并采用随机森林机器学习算法表征覆膜农田信息。研究表明,结合利用Sentinel-2A数据与OBIA方法能够有效表征覆膜农田信息,总体精度达93.03%,Kappa系数为0.91;其中,灌水覆膜农田用户精度为91.35%,制图精度为88.57%;无灌水覆膜农田用户精度为97.10%,制图精度为98.63%。研究证明了Sentinel-2A卫星数据和OBIA方法和机器学习算法在覆膜农田信息遥感表征中的应用潜力,能够为地物信息遥感表征研究中提供参考依据。 相似文献
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由于数据量大,目前大多数端元提取算法均需较长的计算时间,限制了这些算法的有效应用。本文提出了以光谱梯度特征为搜索条件的快速端元提取方法,其核心包括基于光谱梯度特征的候选端元快速筛选和基于光谱解混误差的端元识别两部分。由于能够从影像中快速筛选出少量的像元光谱作为候选端元,故具有较好的计算性能;同时由于避免了非端元光谱参与端元识别,使得识别的结果具有更高的精度。试验表明,相比经典的IEA算法和ECHO算法,该算法不仅能大幅度提高端元提取速度,而且具有更准确的端元识别能力。同时,基于该算法原理,也可对现有各种算法进行改进,提升现有的各种端元提取算法的运算速度。 相似文献
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提出了一种用于Stokes积分和Hotine积分直接离散求和的快速算法。该算法将积分核表达为计算点纬度、流动点纬度和两点间经度差的函数,充分利用核函数的对称性,相同纬度的所有计算点只需计算一组核函数,计算次数远少于普通离散求和。基于EGM2008地球重力位模型的模拟实验表明,快速算法的计算效率远高于普通算法,有效解决了离散求和计算速度太慢的数值问题,且保留了球面积分的特性,可取代一维FFT用于计算Stokes积分和Hotine积分。 相似文献
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低轨道地球卫星(LEO)的精度直接影响到LEO卫星的应用领域,因此研究合适的模型提高LEO卫星轨道插值/预报精度是一项很有意义且必要的工作. 本文详细研究了滑动切比雪夫多项式、克里金算法在不同类型LEO轨道的拟合、预报精度. 结果表明:采用合适的拟合策略,两种算法均能获得毫米级的插值精度;相较于滑动切比雪夫多项式,克里金算法拟合轨道的空间误差分布更为集中,未随着历元变化出现大幅波动. 克里金算法预报轨道的精度低于滑动切比雪夫多项式;采用克里金算法预报60 s,各颗LEO卫星轨道预报的精度在1~2.5 m;采用滑动切比雪夫多项式预报120 s,各颗LEO卫星可获得优于5 m的轨道精度. 相似文献
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Jaechoon Chon Hyongsuk Kim Chun-Shin Lin 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(1):86-92
This paper presents a novel algorithm that selects seam-lines for mosaicking image patches. This technique uses Dijkstra’s algorithm to find a seam-line with the minimal objective function. Since a segment of seam-line with significant mismatch, even if it is short, is more visible than a lengthy one with small differences, a direct summation of the mismatch scores is inadequate. Limiting the level of the maximum difference along a seam-line should be part of the objective in the seam-line selection process. Our technique first determines this desired level of maximum difference, then applies Dijkstra’s algorithm to find the best seam-line. A quantitative measure to evaluate a seam-line is proposed. The measure is defined as the sum of a fixed number of top mismatch scores. The proposed algorithm is compared with other techniques quantitatively and visually about various types of images. 相似文献
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G. S. Srivastava R. B. Sharan R. P. Sharma 《Journal of the Indian Society of Remote Sensing》1977,5(2):47-55
The authors interpreted a major lineament in Ladakh region on LANDSAT imagery and named it Nubra-Gartang superlineament, after the two livers along which it is aligned for a considerable distance. The superlineament trending NW-SE, extends for a distance of 750 km from the Afganistan border to southern Tibet. Structural and geomorphic evidences indicate that the lineament is perhaps still active and represents a dextral strike-slip fault. The fracture pattern and other tectonic elements suggest that a ‘suture’ zone is expected further to the north of this line in the Pamir region and the so called ‘Indus suture zone’ may be only a sister fracture to this superlineament. Occurrences of Quaternary volcanics along the superlineament are not ruled out and as such the zone offers a favourable locale for associated mineralisation. 相似文献
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Colour distortion, which is caused by the unavoidable mismatch between a map’s gamut and a device’s gamut, negatively affects the semiotic quality of maps. Cartographic communication often suffers from undesirable colour inconsistency. This method models cartographic colour reproduction as a constrained transform problem, namely, adapting a map’s gamut to fit a device’s gamut while preserving the semiotic quality. First, the characteristics of the map’s gamut are investigated by considering cartographic principles, and the fundamental concerns of preserving semiotic quality are proposed. Then, the self-organizing map method is introduced to iteratively optimize the cartographic colour reproduction. We implement this method and evaluate it based on a series of thematic maps. The results indicate that the proposed algorithm offers better results than two alternatives in terms of facilitating cartographic colour reproduction. 相似文献
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Investigating the Effectiveness of an Efficient Label Placement Method Using Eye Movement Data 总被引：1，自引：0，他引：1
《The Cartographic journal》2013,50(3):234-246
AbstractThis paper focuses on improving the efficiency and effectiveness of dynamic and interactive maps in relation to the user. A label placement method with an improved algorithmic efficiency is presented. Since this algorithm has an influence on the actual placement of the name labels on the map, it is tested if this efficient algorithms also creates more effective maps: how well is the information processed by the user. We tested 30 participants while they were working on a dynamic and interactive map display. Their task was to locate geographical names on each of the presented maps. Their eye movements were registered together with the time at which a given label was found. The gathered data reveal no difference in the user’s response times, neither in the number and the duration of the fixations between both map designs. The results of this study show that the efficiency of label placement algorithms can be improved without disturbing the user’s cognitive map. Consequently, we created a more efficient map without affecting its effectiveness towards the user. 相似文献