Automating Landscape Illustration with Pen and Ink Style Rendering

This paper introduces object space procedures for extracting silhouettes, slope lines, and drainage features from digital elevation models (DEMs) to direct the rendering of landform features in the style of pen-and-ink landscape illustrations. Unlike image space procedures which generally extract feature information through 2-dimensional (2D) rendered image processing techniques, object space procedures operate directly on 3-dimensional (3D) surface models. The ultimate goal of this work is to produce fully automated tools that can imitate the styles characterized by the traditional pen-and-ink techniques of Lobeck, Imhof, Raisz, and other scientific illustrators to bring the beauty of their effective and economical visual techniques to automated cartographic environments. Through the implementation of a Java 3D application programming interface (API) prototype, a testing platform was established for the application of stylistic elements to linework representing surface form lines. This paper explores the aesthetic effects of silhouette lines, creases, and slope lines on the rendering of terrain features. It also introduces the use of adaptively resampled triangulated irregular networks (TINs) as a basis for perspective rendering applications.     

A Hybrid System of Expanding 2D GIS into 3D Space

A hybrid system that integrates two-dimensional (2D) GIS and three-dimensional (3D) visualization has been developed to provide unique solutions to application domains where traditional 2D GIS and 3D visualization cannot alone provide a solution. In this paper, we focus on three key issues in realizing such an integrated system, including large-scale terrain rendering, 2D and 3D combination display (for example, rendering 2D GIS layers in 3D space), expanding traditional 2D GIS analysis functions into a 3D environment, and visualizing 3D geographical data. A generic framework is developed to integrate 3D visualization with various types of 2D GIS, such as commercial GIS software, open source GIS software and spatial databases. A prototype 2D and 3D hybrid system that seamlessly integrates 2D GIS (developed with ArcEngine) and 3D rendering engine (developed with DirectX) is then developed based on the framework. In this hybrid system, 2D and 3D data are viewed within the same scene. Multiple 2D GIS layers are overlaid on the base terrain using a Level of Detail (LOD) model. Advanced query functions, data accessing, data management and spatial analysis, which are executed in the traditional 2D GIS, are provided to users in a 3D environment by continuously transforming information between the 2D GIS subsystem and the 3D subsystem. The 3D data are organized and displayed by Keyhole Markup Language (KML) and textured 3D models in the COLLAborative Design Activity (COLLADA) format. The prototype demonstrates that this hybrid system has effectively addressed the three key issues identified above and that it can seamlessly integrate 2D GIS and 3D visualization. The hybrid system has great potential to be employed in many application domains, such as urban planning, landscape design and environmental decision making, among others, to enhance the 3D design capability and facilitate public participation in the planning, design and decision-making process.     

基于三通道投影式虚拟现实系统的磨山景观重建

在三通道“投影式”VR的硬件基础下,运用MultiGen Creator和Vega进行磨山景观重建,介绍了处理山地道路的方法、模型的光照渲染、特殊效果的设计等关键技术。     

移动环境下自适应地图可视化研究

本文首先介绍了移动地图学的概念框架,然后在对移动环境下自适应地图可视化中涉及的用户模型、上下文模型进行分析的基础上,提出了自适应地图可视化的处理流程,并详细讨论了移动环境下自适应地图可视化中存取速度、显示速度、界面元素放置、载负量、符号设计、色彩设计、图例设计和方向设计这些关键技术的实现。     

Concurrent Drainage Network Rendering for Automated Pen‐and‐ink Style Landscape Illustration

Pen‐and‐ink style geomorphological illustrations render landscape elements critical to the understanding of surface processes within a viewshed and, at their highest levels of execution, represent works of art, being both practical and beautiful. The execution of a pen‐and‐ink composition, however, requires inordinate amounts of time and skill. This article will introduce an algorithm for rendering creases – linework representing visually significant morphological features – at animation speeds, made possible with recent advances in graphics processing unit (GPU) architectures and rendering APIs. Beginning with a preprocessed high‐resolution drainage network model, creases are rendered from selected stream segments if their weighted criteria (slope, flow accumulation, and surface illumination), attenuated by perspective distance from the viewpoint, exceed a threshold. The algorithm thus provides a methodology for crease representation at continuous levels of detail down to the highest resolution of the preprocessed drainage model over a range of surface orientation and illumination conditions. The article also presents an implementation of the crease algorithm with frame rates exceeding those necessary to support animation, supporting the proposition that parallel processing techniques exposed through modern GPU programming environments provide cartographers with a new and inexpensive toolkit for constructing alternative and attractive real‐time animated landscape visualizations for spatial analysis.     

建筑物三维表面模型简化算法探讨

模型简化是近年来计算机图形学中的一个研究热点,并已在虚拟现实、可视化、实时渲染、计算机视觉和渐进传输等众多方向得到广泛应用。本文针对3D建筑物表面模型的自动简化处理,首先对现有模型简化算法及各自的优缺点进行了归纳总结,分析了现有3D建筑物模型简化算法存在的问题,并探讨了3D建筑物表面模型的简化思路。     

地形TIN模型的实时连续LOD算法设计与实现

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模型的买时动态构网显示。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。     

A trajectory-oriented carriageway-based road network data model,part 3: Implementation

This is the final of a three-part series of papers which mainly discusses the implementation issues of the CRNM. The first two papers in the series have introduced the modeling background and methodology, respectively. An overall architecture of the CRNM has been proposed in the last paper. On the basis of the above discusses, a linear reference method (LRM) for providing spatial references for location points of a trajectory is developed. A case study is introduced to illustrate the application of the CRNM for modeling a road network in the real world is given. A comprehensive conclusion is given for the series of papers.     

A Trajectory-Oriented Carriageway-Based Road Network Data Model, Part 3: Implementation

IntroductionThe LRM based on the CRNMis a kind oflink-and-node LRM. As introduced in the firstpaper of the series ,the link-and-node LRMdoesnot designate any fixed reference point along aroad segment in advance but employs the nodesin the node-arc model d…     

A virtual globe-based time-critical adaptive visualization method for 3D city models

3D city models, which are important items of content on the virtual globe, are characterized by complicated structures and large amounts of data. These factors make the visualization of 3D city models highly dependent upon the performance of computer hardware. Thus, achieving the efficient rendering of 3D city models using different hardware performance levels represents one of the key problems currently facing researchers. This paper proposes a time-critical adaptive visualization method that first estimates the possible rendering time for each model according to the data structure of the model in addition to the CPU/GPU performance of the computer. It then dynamically adjusts the rendering level for each model based on the results of an estimation of the rendering time to ensure that the final scene can be completed within a given time. To verify the effectiveness and flexibility of this method, it is applied using different computers. The results show that the adaptive visualization method presented in this paper not only can adapt to computers with different levels of performances but also demonstrates an obvious improvement in the time estimation precision, visual effects, and optimization speed relative to existing adaptive visualization methods.     

三维实体模型的建模技术

三维实体模型是虚拟战场环境建立与应用的重要组成部分。本文重点研究了三维实体模型设计思路和制作技术方法,并以三维武器(飞机)模型作为实例进行了具体实践,阐述了基于3D-MAX设计武器模型的思路及实现过程、模型制作、模型渲染的技术方法。     

三维地形场景并行渲染技术进展

对三维地形场景并行渲染过程涉及的地形数据分页及分块和基于缓存的并行数据调度机制进行了归纳,总结了三维地形场景并行渲染相关算法及基于分布式和微机多线程的实现方式,并对目前并行渲染所存在的问题和发展趋势进行了分析。     

数据仓库及其体系结构建设

数据仓库是一种过程,它是对分布在组织或企业内部各处的业务数据进行整合、加工和分析的过程。本文阐述了数据仓库的概念、产生,展示数据仓库工程实施框架,介绍了数据仓库具体实施的方法论。     

地壳垂直形变模型的研究

本文重点研究了建立整个形变区域的形变速率曲面和形变加速率曲面,同时也研究了求这两种曲面的方法(基于多元逐步回归分析的间接法和直接法),从而使我们对整个形变区域有一个形变的整体概念,也使我们能方便地得出形变区任何一个已知其平面位置的点在任一观测期内的形变量。     

基于虚幻引擎的智能矿山数字孪生系统云渲染技术

HTML5、WebGL、云渲染等技术为浏览器、移动端、XR等多种终端的可视化渲染提供了重要技术支撑。本文分析比较了其优缺点,并采用虚幻引擎4的云渲染技术,采用某煤矿的倾斜摄影、BIM、巷道、设备、三维地质模型开展了系统设计与测试,分析了云渲染的效率和效果,实现了数字孪生云渲染技术在智能矿山的应用。     

On the Quantification of Surface Changes using Grid-based Digital Elevation Models (DEMs)

This paper discusses the quantification of vertical surface displacements by means of grid-based digital elevation models (DEMs). The surface changes are quantified by comparing altitude and different topographic parameters, which have a geomorphic significance with respect to surface changes. This paper describes the choice of different spatial calculation techniques, considering DEM accuracy and the propagation of error for the different topographic parameters involved. The techniques are illustrated on two grid-based DEMs from Finsterwalderbreen, a 35 km2 sized valley glacier on south-western Spitzbergen, Norwegian High Arctic.     

一种实时大数据动态三维可视化技术

提出了一种面向海量实时模型数据的三维可视化方法.通过多线程技术实现实时数据的传输、加载和显存写入;通过GPU实现模型的平滑变化和反抖动处理;通过建立多层LOD简化和实例化技术实现海量数据的渲染性能优化.实验证明,采用本文提出的方法可以有效地提升海量实时数据的渲染性能和渲染效果.     

三维数字景观中场景图的组织与绘制

介绍了场景图的基本概念、场景图的作用和场景图的生成,讨论了应用软件设计模式的思想,实现数码城市的三维数字景观中场景图的组织和绘制技术。     

Web-based visualization of large 3D urban building models

Adaptive rendering of large urban building models has become an important research issue in three-dimensional (3D) geographic information system (GIS) applications. This study explores a way for rendering web-based 3D urban building models. A client–server hybrid rendering approach is presented for large 3D city models, stored on a remote server through a network. The approach combines an efficient multi-hierarchical building representation with a novel image-based method, 3D image impostor generated on demand by a remote server. This approach allows transferring complex scenes progressively while keeping high visualization quality. We also evaluated the rendering and data transferring performance of the proposed approach.     

基于GIS的城市人防工程空间分析模型的建立与实现

为提高城市人防工程的管理水平,利用地理信息系统技术(GIS)的空间分析功能,首先在分析城市人防工程的实体—关系模型(E-R模型)的基础上,根据GIS空间分析的特点,提出了基于空间分析的城市人防工程的数据库结构;其次,根据城市人防工程规划、管理和施工的需要,建立了城市人防工程设备的承载力、辐射范围缓冲图、人口疏散隐蔽路线最佳路径、地下人防工程3维分析等几种空间分析模型,并对各种模型的表示内容和实现方法进行了阐述,从而实现了城市人防工程的可视化和动态化管理。该模型在广州市人防工程综合管理信息系统应用后,提高了广州市的城市人防工程的管理水平,促进了该人防办的数字化进程。