共查询到20条相似文献，搜索用时 62 毫秒
1.
由于硬件条件的限制,超大规模的地形数据不可能在开始阶段全部载入内存进行3维场景渲染.文中提出了一种用于大范围海量地形数据3维显示的动态场景管理方法,该方法按照规则网格贴片对虚拟场景进行剖分,在漫游时根据视点参数建立可见和潜在可见缓冲区来确定当前应该调度和进行渲染的网格单元;在场景漫游时对各个规则网格单元建立具有多细节层次的四叉树,实现了对整个场景的多细节层次渲染. 相似文献
2.
3.
高精度曲面建模的三维地形可视化研究 总被引：3，自引：1，他引：2
根据高精度曲面建模理论(HASM)中曲面单元算法的特点,提出基于视点的多分辨率LOD实时生成算法。该方法通过对规则格网的DEM数据进行划分,以单元分片为基本单位对DEM数据进行组织。根据各曲面单元与视点的相对关系,以不同间距对曲面单元进行内插,实时重建视景内的三维地形。在实时显示过程中,对硬盘中的数据进行实时读取,采用多线程技术对图像渲染操作进行处理,实现了对DEM数据的实时计算、动态显示。该方法无需对规则格网DEM数据建立空间层次组织结构,在对虚拟地形进行实时漫游过程中,存储空间占用少,不受数据规模的影响。 相似文献
4.
针对海量地形数据实时渲染,本文采用开源跨平台三维渲染引擎OSG(Open Scene Graph)技术,设计了一种海量地形快速渲染方案。文中对场景结构的组织和管理、LOD调度等关键技术展开了研究,分析了生成IVE三维模型的分页LOD层次结构,提出了一种海量地形快速渲染的实现方法。试验结果实现了海量地形数据的实时加载、距离坡度测量、多种场景漫游方式以及水淹分析等功能,对工程实践有一定的指导意义。 相似文献
5.
使用多桩段边坡的角点数据插值生成边坡场景的地形数据，运用OpenGL的自动化技术实现了多桩段边坡的3维建模。使用分块纹理映射的方法，克服了OpenGL渲染机对影像纹理大小的限制。应用低分辨率纹理映射和选择边坡增强纹理分辨率的映射的方法实现了场景的快速建立和漫游，解决了对多桩段边坡的大场景渲染效率与分析时需要的视觉效果的冲突问题。研究成果能够被用于实际工程中，为边坡的辅助设计提供了支持。 相似文献
6.
基于RSG虚拟地形环境的ROAM实时绘制 总被引：1，自引：0，他引：1
三维地形绘制在地形仿真、虚拟现实、测绘等领域具有广泛的应用。在数字地球、3DGIS日趋发展的今天，大范围三维地形的实时绘制成为一种必须。大范围地形的实时绘制一般采用场景分块、可见性区域块选择和视点相关的连续多细节层次模型建立等算法。本文通过对规则格网(Regular Square Grid，RSG)数字高程模型的分块管理，实现显示区域的地形简化，在普通微机上实现了大范围地形的实时、交互式、自适应网格(Real—Timt Optimally，Adapting Meshes，ROAM)绘制。 相似文献
7.
8.
为了在大规模地形实时渲染过程中提高渲染效率和得到更平滑逼真的地形,该文提出了一种基于GPU Tessellation技术的地形可视化方法。该方法首先对地形预处理构建四叉树;使用视锥体裁剪和LOD选择降低CPU-GPU数据传输量;在三角化阶段利用GPU代替传统的CPU进行三角化方法极大地减轻CPU的负担并且提高了渲染速率;同时引入地形粗糙度计算GPU Tessellation算法内部细分因子,达到平滑而又不失细节的地形表面渲染效果;以数据细节层次动态设置GPU Tessellation算法的外部细分因子消除了T型裂缝。实验结果表明,该方法CPU利用率低,能够以较小计算代价消除T型裂缝,在地形实时交互式漫游系统中能以较高的渲染帧率输出平滑、逼真的三维虚拟数字地形。该文方法可运用到大规模地形可视化系统中。 相似文献
9.
使用多桩段边坡的角点数据插值生成边坡场景的地形数据,运用OpenGL的自动化技术实现了多桩段边坡的3维建模。使用分块纹理映射的方法,克服了OpenGL渲染机对影像纹理大小的限制。应用低分辨率纹理映射和选择边坡增强纹理分辨率的映射的方法实现了场景的快速建立和漫游,解决了对多桩段边坡的大场景渲染效率与分析时需要的视觉效果的冲突问题。研究成果能够被用于实际工程中,为边坡的辅助设计提供了支持。 相似文献
10.
地形漫游在仿真、模拟、虚拟现实、游戏等领域都有广泛的应用，但其大规模地形实时动态绘制的速度和质量一直是一个难点。文章主要分析了地形场景数据管理与实时调度、视相关多层次细节模型与可见性判断以及分层数据组织与瓦片数据绘制等关键问题。在研究多种层次算法的基础上，提出了一种实时高帧率绘制大规模地形的瓦片重组数据结构的方法，并改进了视景体裁切重组地形数据的方法。实验结果表明该方法在保持地形逼真的情况下，有很好的绘制网格帧率和实时动态交互的效果。 相似文献
11.
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
12.
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
13.
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
14.
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
15.
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
16.
“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
17.
《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
18.
Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei OGAWA Edward VERBREE Sisi ZLATANOVA Naohiko KOHTAKE Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118
Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
19.
20.
地理数据库的关系模型及其实现 总被引：1，自引：0，他引：1
本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4～9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。 相似文献