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由于地物与地形模型分开建模等现实原因,地物模型与地形模型集成的时候会出现不匹配问题。因此,本文通过分析地物与地形之间的空间依存关系,针对地物独立于地形和地物依赖于地形两种情况分别提出了地物模型与地形模型的匹配方案,并着重研究地物依赖于地形时的匹配方案与算法。 相似文献
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三维模型在许多领域内均有着越来越深入的应用,为保证三维模型在不同存储空间、不同图形绘制能力、不同显示分辨率的终端电子设备上显示的统一性和一致性,在很多情况下需要对三维模型进行适度的简化。对于三维地形而言,纹理颜色、地形区域边界和重要顶点是其非常重要的视觉特征,本文将这三项特征作为约束因子引入到三维地形的简化过程中,并根据这三项特征对现有的二次误差测度算法和边折叠代价的计算方法进行了改进,使其在三维地形简化过程中不会出现明显退化。本文还将改进后的算法与原来算法进行了实验对比,结果表明,改进后的简化算法不仅能够在不同精度上保持三维地形视觉上的一致性,而且产生的几何误差也相对较小。 相似文献
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虚拟地形环境中道路与地形模型融合算法研究及精度评价 总被引：1，自引：0，他引：1
以大比例尺地图构建的虚拟地形环境,由于观察视点的接近以及应用中对各种查询和分析的需要,所以要求构建的环境既能准确地表现地形特征又能使地物与地形精确融合,准确地查询出地物的属性,以满足目视及精确定位的要求.然而,实际应用中往往忽视地形与地物的密切关系,从而导致在目视比例尺条件下出现地物飘在空中或钻入地下等失真现象.为此,本文以道路为例提出了道路模型与地形模型的融合算法,同时对融合后道路与地形模型的精度进行了评估,为构建逼真的地理环境提供了基础.也为河流、岛屿、湖泊等地物与地形模型的融合提供参考. 相似文献
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地形TIN模型的实时连续LOD算法设计与实现 总被引：1，自引：0，他引：1
为了实现基于不规则三角网(TIN)地形模型的动态细节简化模型,文中介绍了一种有效的方法,即在一种新的三角网数据结构基础上,通过重复执行模型中边的"折叠"(即顶点"合并")操作,预先计算模型中每个顶点"重要性"值,根据"重要性"对模型的三角形和顶点列表进行重新排序并将结果存储在数据结构中.在显示过程中,根据对地形的精度要求和事先存储的结果自适应地快速获取所要显示的顶点和三角形,实现TIN模型的实时动态构网显示.基于该算法,在两个不同细节的TIN模型进行过渡时可以进行快速线性插值,实现了不同细节模型间的连续过渡. 相似文献
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针对大规模三维地形实时可视化在GIS、虚拟现实、游戏、仿真等领域广泛应用的关键技术与难点,介绍了在四叉树地形数据简化算法的基础上,采用数据分块、基于块节点的视景体裁剪、部分数据常驻内存以及边界裂缝消除等实现对大规模地形数据的快速漫游的方法。实验结果表明,该成果能够实现大规模三维地形的实时漫游。 相似文献
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《武汉大学学报(信息科学版)》2015,(9)
地形特征线的正确拓扑表达是进行地表形态描述、地形拓扑简化和地貌综合的基础。传统的基于Morse复形从三角格网地形提取特征线的算法,存在山谷线与山脊线在正则点处"交叉"及无法识别"宏"鞍点等问题。本文利用Morse复形的对偶特征,提出了一种较为通用的改进算法。该算法将下降(或上升)Morse复形的边界作为提取其对偶复形边界的约束线,并使"宏鞍线"按相应已建复形边界线寻径,不仅消除了传统算法出现的"交叉"现象,而且能够识别"宏"鞍点,实现了整个地形特征线的完整构建。 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