论多边形中轴问题和算法   总被引：9，自引：4，他引：9  

胡鹏  王海军  邵春丽  胡海 《武汉大学学报(信息科学版)》2005,30(10):853-857

比较了当前国内外GIS中和计算几何中关于多边形中轴的定义,讨论了它们的主要特点,指出多边形中轴应是到两个以上边距离相等点的轨迹,并据此分析了相应的各种算法和实际应用场合,提出了理论上较为严密、能够广泛满足实际应用需要的几何方法———点对序列法和地图代数多边形中轴法。  相似文献   

Soil erosion assessment based on minimum polygons in the Yellow River basin, China   总被引：5，自引：0，他引：5  

Jin-Ren Ni  Xiu-Xia Li  A.G.L. Borthwick   《Geomorphology》2008,93(3-4):233-252

In the previous studies, a method was developed to assess soil erosion based on land use information. In this paper, we present another approach that uses environmental data to assess soil erosion. A soil erosion characteristic index EI is proposed, and its value is derived using the Analytic Hierarchy Process (AHP) technique based on standardized environmental information stored in minimum polygons that tile the erodible area under consideration. The approach is applied to a case study of the Yellow River basin, north China, where serious erosion is occurring. To represent different grades of soil erosion, the range of EI is divided into six levels according to standard grades of soil erosion intensity. The application indicates that the method deals properly with data scarcity, with the results giving a satisfactory representation of the characteristics of soil erosion in the Yellow River basin. The spatial–temporal distribution of EI in the Yellow River basin is predicted, and the results interpreted to give the long-term trend and state of soil depletion. Comparisons are given between EI and surveyed soil erosion zoning maps for the Yellow River basin at the end of the 1980s and 1990s. The output reliability and the approach applicability in smaller spatial scales are investigated in a case study of Zhifanggou basin.  相似文献   

Development of polygon shift method for generating 3D view map of buildings     

Shunji Murai  Vivarad Phonekeo  Kunihiko Ono  Shigetaka Yasue 《ISPRS Journal of Photogrammetry and Remote Sensing》1999,54(5-6)

The authors have developed a new method termed “Polygon Shift Method” that enables the generation of a 3D view map of a city with tall buildings with a simplified procedure to shift a polygon and check the overlap between the original and shifted polygon. Boolean operations are applied with a newly defined “Fore or Aft” side and a “Depth Distance” that functionally express the visibility criteria or hidden point processing in the 3D view. Since the polygon shift method can be operated with a raster-based structure, the computer processing for generation of a 3D view map of buildings with shadow is simple and efficient.  相似文献   

利用多边形骨架线生成房屋模型算法研究     

王飞  李成名 《测绘通报》2017,(1):69-73

城市作为人类生活的重要聚集地,是三维GIS应用的主要领域。本文结合房屋的二维轮廓数据与屋顶的基本信息（倾斜角度、屋顶高度、纹理属性）,以“骨架线提取-房屋模型构建”为框架,提出了一种基于多边形骨架线自动生成简单房屋模型的算法,详细描述了该方法的基本思想,并在试验结果的基础上证实了该算法的有效性。  相似文献   

基于DEM的低阶地提取新方法     

张文朋 《地震》2016,36(3):55-66

以相对易于提取的低阶地为研究对象, 提出了一种基于DEM的简便实用的低阶地提取方法。 以构建泰森多边形的方法生成拔河高度数据, 同时结合低阶地发育特征及低阶地分布区拔河高度频度统计, 提出低阶地拔河高度统计图中低阶地识别的客观标志, 从而形成了一套较为系统、 科学的基于DEM的低阶地提取分级方法, 为阶地的定量研究开拓了新思路。 在桑干河王家湾宽谷段进行实验, 结果表明低阶地提取结果与实际吻合较好, 该方法可以应用于阶地野外实测前的室内解译, 使野外调查工作更具有针对性。  相似文献   

对称荷载正多边形孔洞弹性应力解析逼近方法     

朱大勇  蔡永祥 《岩土力学》2016,37(Z2):60-66

提出一种简单有效的计算方法,求解对称荷载作用下含正多边形孔洞无限平面体的弹性应力解。将孔洞内边界向两侧延伸至应力可忽略的远处,其外侧构成半无限平面体。相邻两个半无限平面体有一个公共域,其中一个半无限平面体顶边延伸至相邻两个半限平面体体内。孔洞内边界上面力是已知的,延伸至两相邻半无限平面体体内的顶边上面力可先假设,由弹性理论求出半无限平面体体内应力,再计算相邻半无限平面体顶边上面力,根据对称性得到本半无限平面体顶边上面力改进值,迭代求解直至收敛。该方法具有计算过程简单、精度高等优点。算例分析表明,该方法求解的工程尺度下孔洞周边应力场与复变函数方法、有限元方法计算结果吻合,拟合计算的孔边角点处应力奇异性次数与理论解基本一致。  相似文献   

制图数据多边形区域符号自动填充算法实现   总被引：1，自引：0，他引：1       下载免费PDF全文

张省  隗伟  戚文来 《山东国土资源》2012,28(10):48-50

DLG建库数据是基础测绘生产的主要成果之一,而且在不断的更新,由于很多部门需要DWG格式的制图数据,因此实现DLG建库数据到制图数据的自动转换十分必要。多边形(面)要素是DLG数据的重要组成部分,实现制图数据多边形区域符号自动填充是DLG建库数据到制图数据自动转换的关键部分,该文提出面状区域符号自动填充的方法,该方法考虑到了多种复杂图形的情况,同时解决了小面积区域保证一个符号的问题,实验证明,该方法能够实现DLG入库数据多边形要素到制图数据的自动转换。  相似文献   

Features of Late Cenozoic Deepwater Sedimentation in Southern Qiongdongnan Basin,Northwestern South China Sea   总被引：1，自引：0，他引：1  

Lü Fuliang 《中国地质大学学报(英文版)》2009,20(1)

Based on high resolution 2D and 3D seismic data acquired in recent years,using sequence stratigraphy analysis and geophysical methods,we discuss the features of Late Cenozoic deepwater sedimentation in the southern Qiongdongnan (琼东南) basin.The study area entered a bathyal slope environment in the Miocene.The channel developed in the Sanya (三亚) Formation was controlled by a fault break,and its shingled seismic characteristics represent multiple erosion and fill,which may indicate that turbidite current developed in the slope environment.The polygon faults found in mudstone of the Meishan (梅山) Formation represent the deepwater hungry sedimentary environment.The large-scale channels developed on the top of HuangUu (黄流) Formation could be the result of a big sea level drop and an increase of sediment supply.The fantastic turbidite channel developed in Late Quaternary in the slope environment has "fan-like" body and long frontal tiny avuision channel The analysis of these features suggests that the sediment supply of the study area in the post-rifting period was dominant from the Vietnam uplift in the southwest.These deepwater sedimentary features could be potential reservoirs or migration pathways for deepwater petroleum systems.  相似文献   

基于向量代数的点与多边形拓扑关系的推理     

刘德儿  王永君  闾国年 《大地测量与地球动力学》2011,31(2):89-93

在分析向量代数的几何意义的基础上,提出了利用向量叉积的几何性质来判断点与多边形的拓扑关系,通过判断点生成一个水平向量,通过该向量和多边形各边的向量叉乘运算,利用k分量的符号来判断两向量的位置关系,并对各种位置关系赋予相应的权重值,最后根据权重值之和的奇偶性来判断点与多边形的位置关系。该算法无需计算出实际的交点,同时,还对某些特殊位置关系作了几何等价处理。从程序运行效果来看,该算法具有稳定性高、运行速度快等优点。  相似文献   

一种基于面积平衡约束的图斑化简算法   总被引：1，自引：0，他引：1  

李建林  朱德海  宋晓眉  陈亚婷  杨扬 《地理与地理信息科学》2009,25(1)

保持综合前后各地类土地面积平衡是土地利用数据综合的基本原则.地类图斑是面积统计的最小单元,用常规的线化简算法不但难以保证图斑的地理特性,而且会给面积统计带来不确定性.该文提出一种能够使图斑化简前后面积保持绝对平衡的化简算法,该算法给出了求取图斑群和岛图斑的地理特征点、几何特征点的相关方法,对被特征点分割的综合子弧段运用直线面积平衡和参数曲线面积平衡两种求取平衡线的方式进行化简,基本原理是综合前后弧段切割它们自身的包络矩形面积比相等,且综合后的弧段须落入综合前子弧段的误差缓冲区内.实验表明,该算法不但能保持图斑的形态特征,而且能保持图斑化简前后面积绝对相等.  相似文献