基于RASM的紧支撑径向基函数自适应并行地形插值方法

快速、准确地对地形进行重建以生成数字高程模型是地理信息表达的重要研究内容,径向基函数（radial basis function,RBF）作为一种插值性能较优的空间插值方法,特别适合于重建复杂的地形模型,但随着已知地形采样点数量的增加,RBF插值模型求解速度变慢,同时插值矩阵过于庞大而导致插值模型求解困难甚至求解失败。针对这个问题,本文基于区域分解和施瓦兹并行原理进行地形插值,以紧支撑径向基函数（compact support RBF,CSRBF）构建基于所有地形采样数据的全局插值矩阵,并自适应求解子区域CSRBF插值节点紧支撑半径,基于限制性加性施瓦兹方法（restricted additive Schwarz method,RASM）采用多核并行架构对各局部子区域的插值矩阵进行求解。以某地区数字高程模型（DEM）数据进行插值实验,结果表明,本文方法能够对大规模地形数据进行准确重建,并且具有较高的求解效率。     

基于双三次Hermite插值方法的DEM误差传播分析

针对由双三次Hermite插值所生成的DEM数据,提出了一种新的传播误差估计方法。传播误差估计模型所适用的空间对象包括:线、不规则三角网(TIN)和规则格网等DEM数据。基于统计学中的误差传播定律,推导出了由非线性插值方法所生成DEM的误差传播公式。最后,将由双三次Hermite插值方法所生成DEM的传播误差与先前研究中采用线性插值所生成DEM的传播误差进行对比分析,由此可以更加全面地掌握通过线性插值或者非线性插值方法所生成DEM的误差传播规律。该成果可用于指导对实际生产DEM产品过程中插值方法的选择。     

DEM产品数据质量分析研究与系统实现

本研究针对不同地貌类型,对比分析了不同插值方法生成DEM的误差,总结分析误差的分布规律,探索了提高DEM精度的方法。DEM精度检查与分析软件改进了现有DEM插值软件算法的不足,具有很强的针对性,误差表达可视化效果好,提高了DEM数据质量检查的效率。     

规则格网上双方向性插值DEM精度研究

简要介绍双方向性插值方法的原理，并以线性插值和三次插值过程中的误差传播为基础，利用误差传播定律，推导出双方向性插值方法生成的DEM曲面平均高程误差值，并对线性插值和三次插值公式本身的精度进行分析。     

基于随机过程的格网DEM精度场模型

针对目前DEM格网精度从理论上难于统一量化描述问题,提出一种基于随机过程的格网DEM（grid digital elevation model, grid DEM）精度场模型,该模型从随机过程理论入手,借助DEM的统一插值模型,建立了DEM两类误差（噪声误差和逼近误差）的数学表达,并分析了构成DEM误差的各个分量的数学意义。与已有的模型相比,该模型实现了传统DEM两类误差的统一描述,此外,该模型适用任意插值方式生成的格网DEM的精度评价。     

离散点云构建数字高程模型的插值方法研究

针对消除DEM构建中插值方法选择的随意性问题,该文基于机载LiDAR离散点云数据,以广东省典型城区与山区为实验对象,利用克里金、反距离权重、径向基函数和自然邻域4种插值方法,对插值参数进行优选后构建DEM,使用交叉验证、相关性分析、像元统计量和三维可视化等方法进行精度分析与比较。结果表明:在城区反距离权重插值,不但可以对空值区域进行适当填充和平滑,而且对高程最大、最小值的预测精度也很高;不同插值方法在构建山区DEM时精度相差不大,插值精度可以达到厘米级,其中普通克里金插值效果最佳。对于城区与山区点云数据反距离权重插值法生成的DEM均能很好地反映地表自然形态,为今后LiDAR点云数据构建DEM选择最佳的插值算法以及插值参数提供参考。     

径向基函数算法中插值参数对DEM精度的影响

以多重对数径向基函数插值算法中的插值参数为研究对象,选取了5种不同地貌类型的离散点数据,使用中误差度量指标,研究光滑因子、搜索点数、搜索方向对DEM插值精度的影响,给出插值参数的"最优"取值区间,消除插值参数选择的随意性,更好地指导DEM建模的运用。     

基于规则格网的DEM插值实验

通过地形建模,将6个地形隶属函数按照101×101,112×112,126×126,144×144,168×168,201×201,257×257 7种格网密度生成6种局部地形单元的规则格网DEM;使用反距离加权(IDW)等7种插值算法,将前6种格网密度下的DEM插值成257×257规格;从原始257×257DEM中随机抽取检查点计算残差,并对残差中误差进行分析。通过分组插值实验,运用控制变量法、方差分析等方法研究地貌类型、采样密度和插值算法对DEM插值精度的影响。     

基于点云数据内插DEM的精度比较研究

利用3维激光扫描技术,以云南元谋干热河谷地区冲沟为研究对象,扫描获得大量具有冲沟坐标信息的点云数据。离散的点云数据之间没有明显的拓扑关系,不能表达连续的地表形态,通过建立格网DEM可视化表达地形信息,利用不同的内插方法生成DEM并进行精度评定,以便在不同的地貌区和采点方式下选用最佳的内插模型。点云数据经过数据配准拼接以及噪声剔除,在ArcGIS软件中,通过数据格式转换,利用反距离加权插值、克里金插值、自然领域法插值三种不同的内插方法生成DEM模型,通过检查点法分析已有的固定点高程和内插相应点的高程值做误差比较,分析不同的内插精度。实验表明,反距离加权插值法和克里金插值中误差基本相同,自然领域法插值中误差最大。分析比较不同的内插精度,对地表的坡度、坡向、等高线的研究具有重要的意义。     

一种紧支撑权函数性质的推导及空间插值实验

在空间插值方法中,权函数是影响空间插值精度的重要因素之一,通常需要选择具有性质较好的权函数进行空间插值。推导一种紧支撑权函数的性质,以铁矿品位为数据源,采用紧支撑权函数进行空间插值,最终验证该紧支撑权函数的优良性质:具有较高的插值精度。推导的紧支撑权函数性质可为后期构建新的紧支撑权函数作为一种借鉴。     

阿克苏河-塔里木河水系水质污染遥感监测与评价

 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。     

Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data

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.     

Landslide risk analysis between Giri and Tons Rivers in Himachal Himalaya (India)

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.     

Gravity Changes Before Large Earthquakes in China: 1998-2005

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...     

GNSS系统及其技术的发展研究

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.     

“4D”技术及其应用

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。     

Virtual Australia: its key elements – know,think, communicate

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.     

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

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.     

地理数据库的关系模型及其实现

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。     

GIS空间数据的采集误差及其分析

本文详细阐述了GIS数据采集过程中的误差来源，重点分析了通过地图、遥感和摄影测量等方式采集数据所产生的误差及其特性，分析了其对GIS数据的影响与消减方法。