Simulation Modelling Applied to Runoff Modelling Using MapScript

Dynamic spatial analysis addresses computational aspects of space–time processing. This paper describes the development of a spatial analysis tool and modelling framework that together offer a solution for simulating landscape processes. A better approach to integrating landscape spatial analysis with Geographical Information Systems is advocated in this paper. Enhancements include special spatial operators and map algebra language constructs to handle dispersal and advective flows over landscape surfaces. These functional components to landscape modelling are developed in a modular way and are linked together in a modelling framework that performs dynamic simulation. The concepts and modelling framework are demonstrated using a hydrological modelling example. The approach provides a modelling environment for scientists and land resource managers to write and to visualize spatial process models with ease.     

《新疆维吾尔自治区资源经济地图集》设计与创新

《新疆维吾尔自治区资源经济地图集》的编制设计是一项涉及面广泛,以地理空间数据集为基础,通过对各种多源数据的分析、处理、加工,以专题地图符号、图表的形式表达新疆地理地貌特征、资源环境保护、自然景观,以及社会经济状况。本文重点探讨了地图集的总体框架设计及专题数据内容选取及数据坐标转换,多源数据融合方法、卫星影像图、鸟瞰图、地貌晕渲、地势、地图专题符号设计、地图集色彩的统一协调等关键技术进行阐述。     

基于动态分段的道路网示意性地图模型综合

针对传统弧段-结点模型不能完整有效地表达道路网的几何与属性特征,提出了基于动态分段的道路网示意性地图综合模型。即按照道路网属性一致性、图形延续性等原则组织道路网路径实体,以完整路径线状实体为单元,采用基于路径的道路网图形简化、移位一体化处理方法,实现道路网地图快速示意化。实验对比分析结果表明,基于动态分段的道路网示意性地图表达更加清晰、有效。     

基于本体的水系要素数据集成方法研究

简单论述了地理本体的基本概念、结构,介绍了地理本体的建模方法,提出了基于地理本体的空间数据集成框架,采用基于公共属性模板的多本体向标准本体集成的混合构架,以水系要素中的“干出滩”类为例,实现了基于地理本体的空间数据集成过程及其数据的转换,解决了数据语义异构性所带来的数据共享难题。     

CryoSheds: a GIS modeling framework for delineating land-ice watersheds for the Greenland Ice Sheet

Choice of watershed delineation technique is an important source of uncertainty for cryo-hydrologic studies of the Greenland Ice Sheet (GrIS), with different methods yielding different watersheds for a common pour point. First, this paper explores this uncertainty for the Akuliarusiarsuup Kuua River Northern Tributary, Western Greenland. Next, a standardized, semi-automated modeling framework for generating land-ice watersheds for GrIS land-terminating ice (henceforth referred to as CryoSheds) using geographic information systems (GIS) hydrologic modeling tools is presented. The framework uses ArcGIS and the ArcPy geoprocessing library to delineate two types of land-ice watersheds, namely those defined by: (1) a hydraulic pressure potential with varying water to ice overburden pressure ratios (k-value), which determines theoretical flow paths from the hydrostatic equation, using surface and bedrock digital elevation models (DEMs) and (2) a surface topography DEM alone. Lastly, a demonstration of the CryoSheds method is presented for seven remotely sensed proglacial pour points along the Aussivigssuit River (AR), Western Greenland, and its largest tributaries. GrIS meltwater runoff from these seven nested land-ice watersheds is estimated using Modele Atmospherique Regional (MAR) v.3.2 and runoff uncertainties due to watershed delineation parameter selection is estimated.     

LIDAR Data and Hydrological Applications at the Basin Scale

Digital elevation models (DEMs) resulting from LIDAR (light detection and ranging) surveys are now more available in the hydrology and hydraulics (H&H) community, not only for hydraulic applications in small areas close to river networks but also for hydrologic applications in whole basins. Several questions arise when trying to combine LIDAR data and hydrologic models. Despite the long processing time, LIDAR-derived DEMs can provide more accurate information that is useful for basin hydrogeomorphic characterization, in comparison with DEMs at resolutions commonly used in hydrologic applications (cell size 20-30 m). Of particular focus here are river network properties and the instantaneous unit hydrograph (IUH) framework. Two case studies, one in Italy and the other in the USA, are presented in which three DEMs are analyzed with differing resolutions as follows: "standard," i.e., a resolution commonly used in hydrologic applications (cell size 20-30 m), LIDAR (cell size 1-2.5 m), and LIDAR-resampled at the same resolution as the "standard" DEM. Results suggest that the higher spatial resolution LIDAR-derived data are preferable and can introduce more detailed information about basin hydrogeomorphic behavior.     

An evaluation of unsupervised and supervised learning algorithms for clustering landscape types in the United States

Knowledge of landscape type can inform cartographic generalization of hydrographic features, because landscape characteristics provide an important geographic context that affects variation in channel geometry, flow pattern, and network configuration. Landscape types are characterized by expansive spatial gradients, lacking abrupt changes between adjacent classes; and as having a limited number of outliers that might confound classification. The US Geological Survey (USGS) is exploring methods to automate generalization of features in the National Hydrography Data set (NHD), to associate specific sequences of processing operations and parameters with specific landscape characteristics, thus obviating manual selection of a unique processing strategy for every NHD watershed unit. A chronology of methods to delineate physiographic regions for the United States is described, including a recent maximum likelihood classification based on seven input variables. This research compares unsupervised and supervised algorithms applied to these seven input variables, to evaluate and possibly refine the recent classification. Evaluation metrics for unsupervised methods include the Davies–Bouldin index, the Silhouette index, and the Dunn index as well as quantization and topographic error metrics. Cross validation and misclassification rate analysis are used to evaluate supervised classification methods. The paper reports the comparative analysis and its impact on the selection of landscape regions. The compared solutions show problems in areas of high landscape diversity. There is some indication that additional input variables, additional classes, or more sophisticated methods can refine the existing classification.     

利用ArcGIS生成水系密度的方法

介绍利用地理信息系统软件ArcGIS生成水系密度图的思路和方法。文章以DEM数据为基础,利用ArcGIS中的水文分析功能自动提取水系。水系经过与网格相交、重新统计总长度、连接等操作,最后得到水系密度图。以徐州地区为例,说明该方法的通用性与可行性。     

神经网络计算机及其在遥感应用中的展望

本文概述了神经网络计算机的基本特点、神经网络的形式化描述、目前国际上神经网络计算机的现况以及在遥感图像处理中应用的潜力和展望。     

面向服务的GIS与Web开发问题探讨

当前Web GIS的发展已经日趋成熟,各种Web GIS的应用也正层出不穷,基于标准的服务架构是这个GIS发展阶段的一个重要特征。在开发的过程中可以使用ArcGIS Server的ADF或者Rest API等许多方法来实现,最后按照一定的标准发布为服务,从而使这些功能变得更加通用,这样可以从整个ArcGIS Server出发来探讨GIS与Web开发中的问题,本文中将在ArcGIS Server体系框架下讨论几个具体功能的实现问题。     

基于ArcGIS的多波束声纳数据库的建立

针对多波束数据的特点,结合ArcGIS建立数据库的优势,提出了基于ArcGIS来构建多波束声纳数据库的方法。介绍了多波束数据野外采集、内室数据处理流程,测深数据、网格化数据及回波强度数据特点。以多波束实测数据为例建立数据库,满足了用户对多波束数据的多样化查询,实现了多波束数据的科学化、标准化管理。     

遥感影像地图在线服务系统设计与实现

针对遥感影像地图服务中存在的问题,本文提出了基于网络的遥感影像地图服务,设计了基于ArcGIS Server的遥感影像地图服务系统的整体框架及相关功能模块,研究了实现系统所涉及的关键技术,最后在开源环境Eclipse下用Java编程实现了遥感影像地图服务系统,为遥感影像的网络应用提供了一个服务平台。     

Optimal Routefinding Across Landscapes Featuring High‐cost Linear Obstacles

Existing GIS‐based least‐cost routefinding approaches can in some cases be confounded by linear features in the landscape whose crossing costs are high relative to other traversing costs found throughout the landscape. Unfortunately, such high‐cost linear features are not uncommon; they frequently occur in the form of hydrologic features whose crossing costs are high relative to costs of traversing the surrounding dry land. This study (1) enumerates the situations where existing approaches can fail, (2) proposes a simple method for overcoming the limitations of the existing approaches, and (3) conducts an experiment to assess the impact of the weaknesses of existing approaches and the magnitude of the differences between the results produced by existing and revised approaches. Our results show that in mountainous terrain, linear hydrologic features with high crossing costs can have a profound impact on least‐cost routes, and the choice of solution method has equally profound impacts on the optimal route produced by the analysis.     

基于ArcGIS的水文流域分析及应用

在理解基于DEM数据进行水文分析的基本原理的基础上,利用ArcGIS提供的水文分析工具对DEM数据水文流域进行了分析和研究,并将其运用于实际生产生活中,为险情预报、土质研究、降水分析等提供了帮助。     

青藏高原水系特征遥感影像解译方法研究

我国西部地区1∶50000地形图的缺失,制约了该区域经济建设和社会发展,给我国西部大开发战略的实施带来了困难。影像解译是整个测绘工程中的关键环节之一,水系特征又是各类地物中的关键要素。本文通过对不同影像中青藏高原水系特征的解译,结合其它技术手段,综合运用各类信息,在此基础上提出了针对不同水系特征的解译提取方法。结果表明,针对不同水系特征的特点,利用不同的遥感数据源,结合其它技术手段,加上各类信息的运用,能够有效地提取青藏高原的各类水系特征,基本能够满足1∶50000地形图的测绘需求。     

基于深度残差网络的机载LiDAR点云分类

机载LiDAR点云的分类是利用其进行城市场景三维重建的关键步骤之一。为充分利用现有的图像领域性能较好的深度学习网络模型,提高点云分类精度,并降低训练时间和对训练样本数量的要求,本文提出一种基于深度残差网络的机载LiDAR点云分类方法。首先提取归一化高程、表面变化率、强度和归一化植被指数4种具有较高区分度的点云低层次特征;然后通过设置不同的邻域大小和视角,利用所提出的点云特征图生成策略,得到多尺度和多视角点云特征图;再将点云特征图输入到预训练的深度残差网络,提取多尺度和多视角深层次特征;最后构建并训练神经网络分类器,利用训练的模型对待分类点云进行预测,经后处理得到分类结果。利用ISPRS三维语义标记竞赛的公开标准数据集进行试验,结果表明,本文方法可有效区分建筑物、地面、车辆等8类地物,分类结果的总体精度为87.1%,可为城市场景三维重建提供可靠的信息。     

基于特征的模糊神经网络遥感图像目标分类识别

特征是图像处理中用于辨识目标的最基本属性.提出了利用模糊神经网络方法,针对舰船的几何特征、矩特征和纹理特征进行舰船目标识别处理.首先简单地描述了几何特征、矩特征尤其是Hu矩特征、一阶纹理特征和二阶纹理特征.然后分别对仿真数据、卫星观测数据中的舰船目标,以及自动检测处理获取的舰船目标的几何特征、Hu机特征和纹理特征进行了提取和分析.模糊神经网络方法可以综合模糊集理论和神经网络方法的优势,有效地实现基于特征的图像目标分类识别处理.文章首先描述了一种主从神经元结构的模糊神经网络分类识别方法,然后利用该方法对大型舰船进行分类识别,包括基于单类舰船特征的分类识别和基于多源(时相)数据融合的分类识别.实验结果表明,基于大型舰船的几何特征、矩特征和纹理特征,利用模糊神经网络方法可以实现对大型舰船目标的有效分类识别.通过多源数据融合处理,可以改善分类识别效果.     

按区域自动批量裁剪地理数据的建模方法

ArcGIS中文件地理数据库是常用数据格式。经常需要按其所辖单元区域批量裁剪输出地理数据。针对常规的手工操作不仅费时且易出错,本文提出基于ArcGIS ModelBuilder(模型构建器)建立模型工具的方法来实现地理数据库按区域自动批量的裁剪输出。该方法使用模型工具嵌套的方式,利用迭代要素类建立裁剪子模型工具对地理数据库中全部要素类依次进行裁剪,再将裁剪子模型工具嵌套到主模型工具中,使用迭代要素选择按区域逐个选择裁剪要素,直至完成所有区域对地理数据的裁剪输出。     

多时相遥感数据在四川省茂县景观生态安全格局评价中的应用

以Landsat系列遥感数据为基础数据源,基于"压力-状态-响应"模型和景观生态学理论,采用层次分析法构建茂县景观生态安全评价指标体系,利用综合指数法分别获取研究区2000年、2007年、2015年的景观生态安全综合指数值;并结合景观生态安全系统分级标准用ArcGIS软件将四川省茂县的景观生态安全状况,定量分析出危险级、风险级、敏感级、良好级、安全级5个等级;再利用转移矩阵剖析2000—2015年期间四川省茂县景观生态安全动态变化过程。研究表明:茂县生态安全状况之间的转换平稳,且转换面积和比重保持在一定的范围。该研究思路与研究结果可为四川省茂县区域宏观规划及山区地貌景观有效评估提供参考与借鉴。