共查询到20条相似文献,搜索用时 46 毫秒
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顾及特殊地物的等高线自动生成浅析 总被引:1,自引:1,他引:0
以自定义实体作为等高线自动生成的载体,构造了以AcDbEntity为基类的CContour实体.通过该实体自动生成所需要的等高线。在讲述了等高线自动生成的一般过程后,强调在构造Delaunay三角网时,应考虑到地性线和特殊地物对Delaunay三角网构造的影响,利用它们对构造好的Delaunay三角网进行修正,从而构造出准确的Delaunay三角网。这对等高线生成设计有参考意义。 相似文献
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针对平面点集空间分布的复杂性,本文提出了一种基于Delaunay三角网的平面点集形状重构方法。首先采用一种简单且实用的数据结构以表达Delaunay三角网中嵌入的几何信息和拓扑信息,然后由外向内迭代过滤Delaunay三角网得到一个大概边界,最后进一步考虑边界的凹凸信息和空洞现象,获取最终的精细边界。试验结果表明与其他典型的Delaunay三角网重构方法相比,本文提出的算法能更好地适用于平面点集空间分布的复杂性,通过所构建的数学模型实现了凸凹多边形内外边界提取。 相似文献
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基于Delaunay三角网提取的骨架线是地图综合中广泛应用的一种空间剖分结构。改进了一种基于约束Delaunay三角网的地图目标群间骨架线提取算法,从程序设计的角度详细描述了算法的数据结构和控制流程。按照三角网中三角形包含约束边的数目,将三角形分为0、1、2、3四类,将0类、2类和单连通的1类三角形视为骨架线追踪的起点或终点,将双连通的1类作为中间通道,对整个三角网进行遍历。针对三角网中的环路、3类三角形等特殊情况,在改进的算法中提出了相应的处理方法。该算法成功地用于等高线的内插和街区地图目标群的邻近分析,验证了算法的可行性和健壮性。 相似文献
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针对三角形约束下影像匹配方法的实际应用,分析了所采用的数据结构与Delaunay三角网动态更新,提出了一种高效的实现算法,实际应用验证了其实现的有效性。 相似文献
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平面离散点集的不规则三角网自动生成算法的实现研究 总被引:2,自引:0,他引:2
本文结合逐点插入法和凸包收缩法的优点,给出了一种具体的Delaunay三角网实现算法。实验结果表明,该算法建立的二角网无交叉和重复,并具有Delaunay三角网的特性,同时兼顾了空间和时间性能,整个过程简单实用。 相似文献
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一种动态构建Delaunay三角网的算法 总被引:3,自引:0,他引:3
Delaunay三角剖分算法是构建数字高程模(DEM)的主要算法。在分析现有的Delaunay三角剖分的3种算法之后,指出现有算法存在的不足。并提出一种TIN的动态建模方法,利用分块技术来改进搜索方法,大大提高了Delaunay三角网的构建速度。实验结果表明,此算法和前面3种算法相比,效率有了很大提高。 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
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Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引:5,自引:0,他引:5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献
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Piyoosh Rautela Ramesh Chandra Lakhera 《International Journal of Applied Earth Observation and Geoinformation》2000,2(3-4)
The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies. 相似文献
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ZHAN F. Benjamin 《地球空间信息科学学报》2011,(1)
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200... 相似文献
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GNSS系统及其技术的发展研究 总被引:3,自引:1,他引:2
阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议. 相似文献
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“4D”技术及其应用 总被引:13,自引:0,他引:13
介绍“4D”(即数字地面模型、数字正射影像、数字栅格地图和数字线划地图)系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。 相似文献
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《International Journal of Digital Earth》2013,6(1):66-87
Abstract Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised. 相似文献
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自动车辆定位导航系统中传感器的误差分析 总被引:1,自引:0,他引:1
对国界定位导航系统中几种常见的辅助传感器所产生的误差进行了分析,导出了不同传感器的误差模型。这些误差模型是估计车辆位置的扩展卡尔曼滤波器的基础,同时也为选择适当的传感器提供了理论根据。 相似文献