基于数据应用及系统构架的流域三维可视化研究

随着流域综合治理的进展和大型水利工程的兴建,从宏观了解流域的自然条件在流域管理中具有重要的意义。流域三维可视化作为一种新的管理方法和技术手段在流域管理中越来越体现其重要性。而流域三维可视化的关键在于其数据应用和系统架构。该文从数据应用和系统架构角度对流域三维可视化进行了研究。采用永定河潮白河流域DEM数据及ETM＋遥感数字影像数据进行三维建模,在VC＋＋平台E基于Vega进行了二次开发,实现了流域三维可视化的基本功能,并探索了多级LOD和多线程调度等相关技术。该文通过在数据应用和系统架构进行比较选择,提出了流域三维可视化的优化组合及解决方案。     

车祸再现中三维车辆模型准确检索方法研究

研究交通事故再现中根据三维模型的车辆检索问题。为解决事故责任的确定,需要根据视频记录通过车辆三维模型的检索结果再现交通事故过程。交通事故发生过程中,车辆因事故碰撞发生车体旋转,使得车辆三维特征不明显,传统的基于骨架特征的三维车辆检索方法由于车体的旋转,不能有效获取车辆特征,造成车辆三维模型检索的准确率不高。为解决此难题,提出基于同心球特征提取的三维车辆模型检索方法,选取车辆的质心作为模型球心,依据最大半径均分原则得到多个同心球,选取与球心最远的凸点为特征点,这样选取的特征点与空间坐标位置无关,避免了车体旋转对特征点的影响,通过匹配完成检索。实验表明,同心球特征提取方法能够提高三维车辆模型的检索准确性。     

基于虚拟现实技术的流域仿真系统实现

讨论了基于MultiGen_CreatorPro和Vega的流域仿真系统的实现方法。通过采用密云官厅水库上游地区DEM数据及15m分辨率ETM＋遥感数字影像数据进行三维地形建模,开发了一个基于MFC的密云官厅水库上游流域仿真系统,实现了流域仿真系统的基本功能,并探索了多级LOD、多线程调度及虚拟纹理等相关技术。该文通过建立流域三维实时、交互的地形仿真环境,提出了基于虚拟现实技术的一种建设流域仿真系统的解决方案。     

面向仿真的流域三维地形加工过程研究

三维地形是虚拟自然环境中不可缺少的因素，也是虚拟仿真视景系统的重要组成部分，但是地形真实性和虚拟仿真系统的快速性构成矛盾。针对这一矛盾，结合“数字清江”项目，介绍了流域三维地形模型两种加工方法(即地形图数字化和摄影测量)，增强了三维地形真实性；并针对仿真系统的要求进行模型再加工，提出了三维地形按照层次细节模型进行数据简化和地形分块调度的思想，提高仿真系统速度。     

利用现有模型修复不完整三维模型

针对通过扫描得到的三维模型经常不完整的问题,提出一种利用现有模型修复不完整扫描模型的方法.首先构建三维源模型库,将现有模型经过选取特征点等处理作为模型库中的源模型;然后选取待修复模型的特征点,通过比较源模型特征点和待修复模型特征点的一致程度,选择出合适的源模型;最后,通过匹配、变形、合并等步骤自动修复不完整模型,得到完整的三维扫描模型.实验结果表明,该方法能很好地修复不完整模型,得到的修复结果是既包含待修复模型的所有组成部分,又对其残缺部分进行合理修复的完整三维模型.     

地形数字高程模型的物理模型快速成形方法

地形物理模型被广泛应用于城市建设、军事战略规划、流域和地质教育等方面,而目前数字地形模型多以数字高程模型数据格式进行存储和显示,为此提出一种将地形的数字高程模型数据直接转换成三维STL模型文件进行快速原型制作的方法.首先对多种格式的数字高程模型数据进行识别转换,根据预设比例和打印精度进行数据简化处理;然后将地形表面数据转换为三角面片,并根据预设阈值进行面片优化和误差修正;最后补充基底和侧壁的三角面片,生成三维STL模型文件,下载到快速成形系统中制作出缩放后的地形物理模型.选取地理特征明显的采样区域进行地形物理模型快速成形实验的结果表明,该方法可以省去中间转换过程,有效减少数据丢失,用更少的时间和更低的成本创建出地形物理模型.     

虚拟现实技术及其在数字流域中的应用

该文介绍了面向21世纪的数字化工程中的数字流域、虚拟现实等重要概念。研究了虚拟现实技术应用于数字流域研发的相关技术：提高图形系统效率的多种细节层次的视景表示、多层次数据管理与视景调度技术，优化界面的多维人机交互技术，流域模型构建以及3S数据在数字流域中的应用模型。讨论了数字流域采用虚拟现实技术在三维漫游，仿真结果叠加，抗洪减灾，开发旅游资源等方面的重要应用。     

三维模型剖面轮廓线的实现

提出一种快速实现三维模型剖面轮廓线的方法．该方法首先求出三维模型与剖切平面的交点．然后对交点按扇型区域进行归类,再在每个扇型区域内选取适当的点构成剖面轮廓线的基准点．最后对选出的基准点拟合,实现三维模型的剖面轮廓线。     

数字孪生水下三维实景数据底板获取技术研究

为了获取高精度的水下三维模型细节纹理结构,满足数字孪生建设对水下三维实景数据底板获取的需求,实现对水下构筑物的实时可视化动态监测,基于GNSS技术、USBL技术研究构建了水陆一体化定位技术,融合水陆一体化定位技术、有缆ROV和水下摄影测量设备等研发了水下摄影测量系统,实现了数字孪生水下三维实景数据底板的获取,并采用多波束测深系统、水下三维全景成像声纳系统等对水下摄影测量系统获取的三维实景模型数据成果精度进行了验证,结果表明：水下摄影测量系统获取的三维实景模型精度满足规范要求,可用于数字孪生流域、工程等水下基础数据底板的建设,也可为水下高精度三维场景重构再现和水利工程水下构筑物实时动态监测提供技术支撑。     

利用三维动态模型进行黄土高原水土侵蚀的定量研究：以延川试验区为例

本文着重介绍了从多时相的遥感数据获取三维动态分析模型的基本方法。利用该方法建立了黄土高原水土侵蚀的分析模型,在此基础上对黄土高原的水土侵蚀情况进行了定量的分析和计算,并对黄土高原(延川)的一块3.2×2.2平方公里地区进行了试验,从中得到了该试验区的水土侵蚀的一系列定量结果,从而为黄土高原水土侵蚀的监控和定量分析提供了新的方法和手段。     

Drought estimation with neural networks

An artificial neural network model is presented to derive streamflow precipitation data. It is tested with actual data coming from a nearby river, referred to a basin area of 356 km² and a time period of 11 years. A feedforward multilayer perception with linear output has been built to deal with this problem. The dynamics are caught by the filter structure of the input layer.

A special study on crossing properties, based on training sample selection,is made to measure the performance of the network for drought analysis. Sample selection leads to increased accuracy within the sample range and degraded performance for points that are clearly out. Predicted number of droughts, average drought length and deficit are compared with the actual data. The results show that very simple neural network models can give fine results.     

Computational methods for a three-dimensional model of the petroleum-discovery process

A discovery-process model devised by Drew, Schuenemeyer, and Root can be used to predict the amount of petroleum to be discovered in a basin from some future level of exploratory effort: the predictions are based on historical drilling and discovery data. Because marginal costs of discovery and production are a function of field size, the model can be used to make estimates of future discoveries within deposit size classes. The modeling approach is a geometric one in which the area searched is a function of the size and shape of the targets being sought. A high correlation is assumed between the surface-projection area of the fields and the volume of petroleum. To predict how much oil remains to be found, the area searched must be computed, and the basin size and discovery efficiency must be estimated. The basin is assumed to be explored randomly rather than by pattern drilling. The model may be used to compute independent estimates of future oil at different depth intervals for a play involving multiple producing horizons. We have written FORTRAN computer programs that are used with Drew, Schuenemeyer, and Root's model to merge the discovery and drilling information and perform the necessary computations to estimate undiscovered petroleum. These program may be modified easily for the estimation of remaining quantities of commodities other than petroleum.     

Modelling and testing spatially distributed sediment budgets to relate erosion processes to sediment yields

Identifying the erosion processes contributing to increased basin fine sediment yield is important for reducing downstream impacts on aquatic ecosystems. However, erosion rates are spatially variable, and much eroded sediment is stored within river basins and not delivered downstream. A spatially distributed sediment budget model is described that assesses the primary sources (hillslope soil erosion, gully and riverbank erosion) and sinks (floodplain and reservoir deposition) of fine sediment for each link in a river network. The model performance is evaluated in a 17,000-km² basin in south-east Australia using measured suspended sediment yields from eight catchments within the basin, each 100–700 km² in area. Spatial variations within the basin in yield and area-specific yield were reliably predicted. Observed yields and area-specific yields varied by 17-fold and 15-fold respectively between the catchments, while predictions were generally within a factor of 2 of observations. Model efficiency at predicting variations in area-specific yield was good outside forested areas (0.58), and performance was weakly sensitive to parameter values. Yields from forested areas were under-predicted, and reducing the predicted influence of riparian vegetation on bank erosion improved model performance in those areas. The model provided more accurate and higher resolution predictions than catchment area interpolation of measured yields from neighbouring river basins. The model is suitable for guiding the targeting of remediation measures within river basins to reduce downstream sediment yields.     

综合集成研讨厅体系及应用研究

定性定量综合集成思想是著名科学家钱学森教授提出的,它既是一个抽象的思想体 系框架,也是一个高度智能化的人机结合系统,其核心是将专家群体、统计数据和信息资料 、计算机技术这三者结合起来,把科学理论与人的经验和知识结合起来,发挥综合系统的整 体优势去解决复杂大系统的问题,也是研究流域可持续发展的可行的方法论．流域可持续发 展是以流域作为特殊区域的一种可持续发展模式,本文将流域可持续发展视为一个整体,提 出了研究“流域可持续发展系统”的思想,在引入“从定性到定量的综合集成研讨厅体系” 的基础上,结合流域可持续发展系统的基本特征,建立了流域可持续发展系统综合集成研讨 厅体系．     

An automatic tool for reconstructing monthly time-series of hydro-climatic variables at ungauged basins

Integrative information models for filling/reconstructing hydro-climatic time-series are required for a variety of practical applications. A GIS-based model for a rapid and reliable assessment of monthly time-series of several key hydro-climatic variables at the basin scale, is here developed as plug-in and applied to the entire region of Sicily (Italy). The plug-in, once the desired basin outlet section and time-window are selected, uses appropriate spatial techniques and algorithms to identify its drainage area and estimate the corresponding mean areal rainfall and temperatures time-series. A recent regional regressive rainfall-runoff model is successively applied for the assessment of the runoff time-series. Finally, a consolidated temperature-based method is applied to estimate monthly potential evapotranspiration time-series, while, actual evapotranspiration and soil moisture storage time-series are derived through a classical water balance model. The tool, supported by a preliminarily developed database, includes automatic procedures for data retrieving and processing and a user friendly interface.     

基于遥感数据的流域土壤侵蚀强度快速估测方法

以北京延庆县境内的妫水河流域为例, 提出了一种基于遥感数据的土壤侵蚀强度快速估测方法。首先, 利用遥感数据和植被指数模型提取流域内土地利用类型信息和植被覆盖度信息; 其次, 利用数字高程模型数据生成坡度图; 然后, 结合土壤侵蚀强度分级指标, 将坡度图与土地类型图、植被覆盖度图空间叠加, 判断和计算侵蚀强度等级, 结果获得了流域土壤侵蚀强度等级图; 最后, 计算了流域的年平均侵蚀模数。结果表明, 妫水河流域的土壤侵蚀以微度和轻度为主, 所占面积比例为74.88% , 极度和剧烈侵蚀很少, 不到总面积的2%。整个流域的年侵蚀模数估计为1 74611/ km ²·a。     

基于遥感解译的比如盆地油气潜力分析与有利区预测

为对国内最具潜力但自然条件恶劣的西藏地区进行油气勘测,用基于遥感解译的技术对比如盆地进行了研究。首先通过对野外踏勘路线上岩性、地层和线性构造的观察,归纳出不同岩性、地层和线性构造在遥感影像图上的特征,建立了岩性、地层、线性和环形构造解译标志,完成了比如盆地岩性、地层、线性构造和环形构造解译。其次应用比值法(油气点微渗漏)、融合法(遥感波段融合色调异常)、主成分分析法(羟基/铁质信息异常)对已知油气出漏点和异常信息进行叠加,发现烃类微渗漏信息异常区与已知油气出漏点存在正相关性,用烃类微渗漏异常信息和已知伦坡拉盆地油藏区叠加,发现烃类微渗漏信息异常区和地下已知油气藏负相关,从而确定了烃类微渗漏非异常区可能为含油气区。通过3种方法得出油气烃类渗漏异常区,进而圈定重点一级烃类微渗漏非异常区一处,并结合盆地的生、储、盖条件,指出了比如-伯列蝉-边坝所圈定的区域为油气勘探有利区域,是未来油气勘探的目标。     

地表通量对模型参数的不确定性和敏感性分析

基于2007年12月22日~2009年12月31日黑河流域阿柔冻融观测站的气象驱动数据,利用通用陆面模型(Common Land Model,CoLM)模拟的地表通量结果,研究地表通量对模型参数(叶面积指数、地表反照率和植被覆盖度)的不确定性与敏感性。结果表明,叶面积指数、地表反照率和植被覆盖度对地表感热和潜热通量不同组分的影响存在较大的差异。其中,植被层的感热和潜热通量对叶面积指数的敏感性程度较高,敏感系数均达到0.7以上;与潜热通量相比,感热通量对反照率更加敏感,土壤感热、植被感热和总感热通量对反照率的敏感系数分别达到-0.96、-0.97和-0.66,而土壤潜热和总潜热通量对地表反照率的敏感系数仅为0.1左右;植被潜热通量对植被覆盖度的敏感性程度很高,敏感系数范围为0.92~0.96,而土壤感热通量对植被覆盖度最不敏感,敏感系数只有0.18左右。     

微型无人机在矿山地质工程测绘中的应用

矿山地质地貌形态复杂,地形起伏变化较大,为工程测绘带来了诸多难题。针对该问题,应用微型无人机技术对矿区进行了多次监测。首先,设计了科学的无人机航摄飞行方案,并采集到测区的影像数据。然后,用三角网加密算法对采集到的数据进行实验,去除了数据中的噪声点,获得了地面点数据。最后,采用局部多项式插值算法构建了无人机航测沉降盆地模型并进行了验证。验证结果表明,微型无人机能较为准确地反映矿山地区沉陷盆地的真实状态,对全面分析地表沉陷规律具有重要的意义。     

Application of remote sensing and GIS for the demarcation of groundwater potential zones of a river basin in Kerala,southwest coast of India

An integrated hydrogeological investigation has been made to delineate the groundwater‐potential zones of the Muvattupuzha river basin, Kerala, along the southwest coast of India. The basin is characterized by charnockites and gneisses of Archean age covering more than 80% of the area and the remaining by Pleistocene laterites and Miocene formation. The basin receives high rainfall, measuring 3100 mm/year. However, acute water shortage occurs during the premonsoon season and hence, a number of dug wells are made to tap the groundwater. Seasonal rainfall during NE and SW monsoons is the major source of groundwater recharge. Further, hydrogeomorphology, geology, fracture systems and the slope of the terrain also play a significant role on the movement and behaviour of the groundwater of this basin. The integration of conventional and remote sensing data has been made through geographic information system (GIS) and it is found that about 50% of the area can be identified as very good or good potential zones, whereas the remaining area falls under moderate and poor categories. Most of the Muvattupuzha sub‐basin and the western part of the Kothamangalam and Kaliyar sub‐basins are classified as good groundwater‐potential zones, although the eastern upstream part of the basin has poor groundwater potential.