约束Delaunay三角剖分的“岛屿”类图斑符号填充     

毛文山  刘涛  杜萍 《测绘通报》2020,(6):32

针对传统方法对“岛屿”类图斑进行符号填充会造成敏感区域符号布局不合理或符号空间冲突的问题,本文提出了一种约束Delaunay三角剖分的“岛屿”类图斑符号填充方法。首先,对“岛屿”类图斑对应的离散点群进行规则网格化和不规则三角剖分,用于计算等值点;然后,依据附加准则增加“凸”形和“凹”形附加点,顺次连接等值点和附加点作为Delaunay三角剖分的约束边界;最后,构建均匀变化的约束Delaunay三角网,在三角网内进行图元积分,填充“岛屿”类图斑符号。利用电子海图中岛屿边界点数据进行试验分析,与传统方法相比,本文方法填充的“岛屿”类图斑符号变化均匀,交互性较强,便于用户修改和切换,进行二次填充。试验结果表明,本文方法适用于“岛屿”类图斑的符号填充。  相似文献   

三角形增长算法构建Delaunay三角网DEM的原理与实现   总被引：1，自引：0，他引：1  

姬安召  兰燕 《四川测绘》2009,32(2):65-69

本文主要论述了三角形增长算法建立Delaunay三角网DEM.首先通过最优边找首三角形,其次通过直线与点几何关系来寻找可能扩展点,通过找最大夹角来判断满足狄洛尼法则的扩展点,最后通过新加入边与已扩展边的数目来判断是否为重复狄洛尼扩展点,符合条件则构建三角网.然后通过空外接圆法则验证了所构三角网符合狄洛尼三角网的条件.狄洛尼三角网的建立和空外接圆的验证程序采用M语言来编写.  相似文献   

Estimation of non-point source pollution loads under uncertain information   总被引：1，自引：0，他引：1  

Ruzhong Li 《中国地理科学(英文版)》2008,18(4):348-355

Many kinds of uncertainties are involved, such as random, fuzzy, grey, unascertained property and so on, in soil erosion process. To exactly predict the non-point source pollution loads, some uncertainties should be taken into consideration. Aiming at the deficiency of present blind number theory being helpless for fuzziness, a novel blind number, i.e. extended-blind number, was introduced by substituting a set of triangular fuzzy numbers （TFNs）, expressed as a-cuts, for interval values in present blind number, and the expected value of extended-blind number was also brought forward by referring to the current blind number theory. On the basis of denoting the parameters of Uni- versal Soil Loss Equation （USLE） as extended-blind parameters, a novel USLE model was established for quantitatively evaluating soil erosion loss and non-point source pollution loads. As a case, the uncertain USLE was employed for predicting the soil erosion loss and non-point source pollution loads of absorbed nitrogen and phosphorus in a dis- trict in the Hangbu-Fengle River basin, in the upstream of Chaohu Lake watershed. The results show that it is feasible in theory to extend blind number into fuzzy environment and reliable on conclusion to apply extended-blind number theory for predicting non-point source pollution loads.  相似文献   

等效法收敛计变形监测     

杨浩 《测绘通报》2011,(12):18-21,36

等效法收敛计变形监测,用以等效代替用收敛计直接量距方法所进行的高空变形监测作业带来的高危险和高代价问题,实现变高空高危险作业为无危险的地面安全作业,可降低工程造价,节省人力、物力和财力。还推荐一种简单易行的特征边组成方法,使得监测工作安全方便且投资小,需要增加的主要辅助设备仅是一些普通细钢丝和一根伸缩杆,基本上实现一人...  相似文献   

三次贝塞尔曲线拼接模型的折线式等值线曲线化应用     

王学春  尚继宏 《测绘科学》2011,36(2):192-194,235

本文通过对曾广鸿等人[1]提出的利用三次Bezier曲线拼接模型实现满足拓扑关系的折线武等值线曲线化的理论方法进行编程实践后,发现仅仅根据文中的方法不能完全正确地实现等值线的绘制,为此作者通过编程实践对该方法进行了补充与完善,文中详细完整地介绍了能完全满足拓扑关系的折线式等值线全参数曲线化的具体实现方法.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987110000332     

Xianglin Gao  Xiaojing M  Xiaoli Li 《地学前缘(英文版)》2011,2(1):57-65

A huge triangle-shaped tectonic region in eastern Asia plays host to numerous major earthquakes. The three boundaries of this region, which contains plateaus, mountains, and intermountain basins, are roughly the Himalayan arc, the Tianshan-Baikal, and longitude line 105°E. Within this triangular region, tectonism is intense and major deformation occurs both between crustal blocks and within most of them. Outside of this region, rigid blocks move as a whole with relatively few major earthquakes and relatively weak Cenozoic deformation. On a large tectonic scale, the presence of this broad region of intraplate deformation results from dynamic interactions between the Indian, Philippine Sea-West Pacific, and Eurasian plates, as well as the influence of deep-level mantle flow. The Indian subcontinent, which continues to move northwards at 40 mm/a since its collision with Eurasia, has plunged beneath Tibet, resulting in various movements and deformations along the Himalayan arc that diffuse over a long distance into the hinterland of Asia. The northward crustal escape of Asia from the Himalayan collisional zone turns eastwards and southeastwards along 95°–100°E longitude and defines the eastern Himalayan syntaxis. At the western Himalayan syntaxis, the Pamirs continue to move into central Asia, leading to crustal deformation and earthquakes that are largely accommodated by old EW or NW trending faults in the bordering areas between China, Mongolia, and Russia, and are restricted by the stable landmass northwest of the Tianshan-Altai-Baikal region. The subduction of the Philippine and Pacific plates under the Eurasian continent has generated a very long and narrow seismic zone along trenches and island arcs in the marginal seas while imposing only slight horizontal compression on the Asian continent that does not impede the eastward motion of eastern Asia. In the third dimension, there may be southeastward deep mantle flow beneath most of Eurasia that reaches the marginal seas and may contribute to extension along the eastern margin of Eurasia.  相似文献   

3维模型数据压缩技术分析     

许敏  张永生 《测绘科学技术学报》2007,24(6):462-466

3维模型越来越广泛地应用于众多领域里,但有限的图形显卡的处理能力和网络带宽严重阻碍了这种媒体的传播.单纯依靠增加硬件设备的投入不足以解决问题,必须采用相应的算法对3维模型数据进行压缩.首先将3维模型数据压缩算法进行分类;然后结合不同的分类情况比较分析了近几年来有代表性的几种压缩算法;最后对该技术今后应着重研究的几个方面进行了总结和展望.  相似文献   

地铁竖井联系测量三角形布设及解算取位的探讨     

吴世明  王世杰  李建章 《测绘与空间地理信息》2018,(6):171-173

在城市地铁竖井平面联系测量中运用误差理论,联系三角形的最优形状进行了探讨。并指出在联系三角形解算时,使用函数型计算器计算时由于两钢丝绳之间的距离S1算的取位不足会导致正弦定理和余弦定理解算的β角存在较大差异。通过对工程实例进行研究,发现只有把两钢丝间距的计算结果保留到0.000 1 mm时,才能使正、余弦定理计算的β角相等,从而保证了井下起始边方位角的正确性和可靠性,避免因联系测量结果有误给工程带来不利影响。  相似文献   

一井定向在地铁隧道竖井联系测量中的应用     

曹先革  贾思水  赵文更 《测绘与空间地理信息》2018,(1):9-11

一井定向是竖井平面联系测量的一种主要方式。本文结合具体工程实例,在分析一井定向原理的基础上,给出了一井定向的作业步骤,总结了一井定向数据的平差计算方法,并设计了具体的计算表格,最后总结了一井定向在实际生产中能够提高定向精度的几点经验。  相似文献   

一种计算线放样中放样点垂直偏差的方法     

崔志勇 《现代测绘》2022,(1):26-28

在河道管理界线划定以及其他一些线状放样的实际工程实践中,对放样点的偏差分析除了包括x方向和y方向的偏差,还需要分析该放样点相对于设计点位所连成的线的垂直偏差,而之前对于这种垂直偏差的分析主要通过在CAD图上手动量取的方式进行.当需要分析大数据量的点位时,很难快速通过手动量取得到分析结果.把两种三角形面积的表达方式同向量...  相似文献