基于机载视频量测的3维城市建模

3维城市模型的快速获取及更新是近十年来计算机视觉及数字摄影测量领域研究的热点。从实用、经济的角度出发，提出了集成城市数字地图、LIDAR data以及机载视频序列影像多数据源，基于数字摄影测量理论的半自动获取3维城市模型的解决办法，并在3维导航的数据生产实践中进行了验证，取得较好的生产效率及效果。     

双向地震激励下隔震结构抗倾覆特性的数值分析

为研究叠层橡胶支座隔震建筑的抗倾覆性能,建立隔震结构在双向地震激励下倾覆力矩时域响应动力分析模型.在对该模型进行简化的基础上,利用结构设计反应谱探讨结构高宽比和结构基本周期等因素对隔震结构抗倾覆力矩与倾覆力矩比值的影响.给出多层和小高层隔震结构在双向地震作用下的抗倾覆安全因数随地震烈度、场地土类别的变化规律.利用本课题...     

虚拟城市建设中纹理库及模型库建立研究

虚拟城市是对城市的三维逼真表达,它不仅具有多种细节层次的几何表达,还提供具有相片质感的表面描述.在虚拟城市建设中,纹理数据及三维模型数据对于虚拟城市建设速度,运行效率,逼真性、沉浸感都有着至关重要的作用.从系统和科学的角度出发,以快速高效构建虚拟城市模型为目的,基于530平方公里虚拟城市模型建设及虚拟小区精细模型建设实践基础,探讨了虚拟城市模型建设过程中纹理库及模型库的建设及应用,解决了传统纹理数据及模型数据的无序、低效利用问题.实践表明,纹理库及模型库对于逼真虚拟城市模型的快速高效构建发挥着至为重要的作用.     

虚拟城市建设中纹理库建立的研究

虚拟城市是对城市的三维逼真表达,它不仅具有多种细节层次的几何表达,还提供具有相片质感的表面描述.在虚拟城市建设中.纹理数据对于虚拟城市建设速度、运行效率、逼真性、沉浸感都有着至关重要的作用.文章从系统和科学的角度出发.探讨了虚拟城市模型建设过程中纹理库的建设,解决了传统纹理数据的无序、低效利用问题.实践表明.纹理库对于逼真虚拟城市模型的快速高效构建发挥着至为重要的作用.     

Study of Assessment Method Based on Coupling Factor of Casualty in Earthquake Disasters in Guangdong Area

In this paper, the rapid assessment method of casualties in earthquake disasters is studied and a casualty assessment model based on coupling factors is established from the perspective of factors affecting casualties in earthquake disasters. Taking Guangdong area as an example, the spatialization and quantification of casualty coupling factors in earthquake disasters are analyzed in detail. A software system is developed based on ARC Engine 10.1 platform. For the same earthquake case, different algorithms (algorithm model based on coupling factor and algorithm model based on building seismic vulnerability) are used to calculate the number of casualties in order to compare research results.     

COMPUTER GRAPHICS AND REMOTE SENSING – A SYNTHESIS FOR ENVIRONMENTAL PLANNING AND CIVIL ENGINEERING

This paper presents efforts undertaken in the field of photo-realistic visualization of natural landscapes using digital elevation models (DEM) and images generated by remote sensing techniques. The remote sensing systems used in this work include Landsat Thematic Mapper, SPOT HRV and aerial photographs. After an appropriate preprocessing, including radiometric corrections and image enhancement procedures, a precise geometric correction is performed in order to achieve a very high co-registration of the images with the elevation model. A mosaic of several images at various resolutions is stored together with the DEM in a data set covering an extensive area. These data are then input to an efficient hardware-independent terrain rendering algorithm based on a forward projection. Atmospheric effects can be simulated. The concept of a virtual scene allows an automated embedding of raytraced 3D objects. The results show that these methods can be used in the field of environmental planning, civil engineering and other applications where terrain visualization is required.     

Virtual reality-based evaluation of indoor earthquake safety actions for occupants

Evaluations of indoor earthquake safety actions can provide effective guidance for occupants, and can be beneficial for reducing earthquake-induced casualties. Accordingly, in this study, a virtual reality (VR)-based evaluation method is proposed for indoor earthquake safety actions. Specifically, an indoor seismic damage scene is constructed based on the Federal Emergency Management Agency (FEMA) P-58 method and a physics engine, by which the damage and movements of indoor nonstructural components can be accurately calculated. Subsequently, a virtual body model is created, and a corresponding inverse kinematics (IK) algorithm is developed to accurately track the earthquake safety actions of occupants. Finally, a human safety model based on collision kinetic energy and fatal conditions is designed for quantitatively evaluating the effectiveness of earthquake safety actions. Taking an office room and living room as case studies, three earthquake safety actions (i.e., “drop, cover, and hold on,” “triangle of life,” and “run outside”) are evaluated using the proposed method. The results indicate that “drop, cover, and hold on” is the safest action in most earthquake scenarios. The outcomes of this study can be used to rate the effectiveness of various earthquake safety actions, and to support occupant safety decision-making.     

一种基于照片中纹理重构三维模型的方法

如何从真实世界中获取具有真实感的三维场景模型一直是计算机图形学中的一个难点.该文给出了一种从真实世界的照片中重建三维场景模型的算法.算法根据在空间稀疏分布的不同视点处的真实场景照片中颜色纹理的一致性来建立达到照片级真实程度的三维场景模型,可用于真实世界复杂形体真实感三维模型的建立.     

Perspective terrain visualization—A fusion of remote sensing, GIS, and computer graphics

Techniques are presented that are used for the perspective visualization of natural landscapes in the field of environmental planning and civil engineering. In order to obtain a photo-realistic visual simulation, we use digital elevation models (DEM) and images generated by remote sensing techniques. The remote sensing systems used in this work include Landsat Thematic Mapper, SPOT HRV, and aerial photography. To achieve high quality perspective views, we first have to pay attention to an appropriate preprocessing of the remote sensing imagery. This includes radiometric corrections and image enhancement procedures as well as a precise geometric correction that is executed to achieve accurate coregistration of the different images with the terrain model. A mosaic of several images at different resolutions is stored, together with the DEM, in a database covering an extensive area. Projection software permits the user to specify all interior and exterior orientation parameters of a virtual camera to compute any perspective view. To obtain greater realism, atmospheric effects can also be simulated. Our visual simulation approach using a virtual scene permits automated image montage of 3D simulated objects. The achieved results show that this technology can be used in many different domains where terrain visualization is required.     

真实感视频雨景编辑

用计算机来模拟雨景是影视制作中经常面临的一个课题。目前主要采用的粒子系统方法一般都需要大量的粒子和复杂的物理模型来模拟真实的雨景。提出了一种新的基于图像的方法来实现真实感雨景的绘制。用最小值滤波和改进的Matting算法相结合的方法,从视频中分割出真实的雨幕,然后根据目标场景的光照条件改变雨幕的颜色,最后将其与目标场景融合在一起。实验证明,该方法十分有效。同时该方法是完全基于视频图像的,避免了昂贵的3D场景建模,适合于低成本的影片制作和影视素材重用领域。     

Detection of collapsed buildings caused by the 1999 Izmit,Turkey earthquake through digital analysis of post-event aerial photographs

In this study, the post-earthquake aerial photographs were digitally processed and analysed to detect collapsed buildings caused by the Izmit, Turkey earthquake of 17 August 1999. The selected area of study encloses part of the city of Golcuk, which is one of the urban areas most strongly hit by the earthquake. The analysis relies on the idea that if a building is collapsed, then it will not have corresponding shadows. The boundaries of the buildings were available and stored in a Geographical Information System (GIS) as vector polygons. The vector building polygons were used to match the shadow casting edges of the buildings with their corresponding shadows and to perform analyses in a building-specific manner. The shadow edges of the buildings were detected through a Prewitt edge detection algorithm. For each building, the agreement was then measured between the shadow producing edges of the building polygons and the thresholded edge image based on the percentage of shadow edge pixels. If the computed percentage value was below a preset threshold then the building being assessed was declared as collapsed. Of the 80 collapsed buildings, 74 were detected correctly, providing 92.50% producer's accuracy. The overall accuracy was computed as 96.15%. The results show that the detection of the collapsed buildings through digital analysis of post-earthquake aerial photographs based on shadow information is quite encouraging. It is also demonstrated that determining the optimum threshold value for separating the collapsed from uncollapsed buildings is important.     

Automatic classification of building types in 3D city models

This article presents a classifier based on Support Vector Machines (SVMs), an advanced machine learning method for semantic enrichment of coarse 3D city models by deriving the building type. The information on the building type (detached building, terraced building, etc.) is essential for a variety of relevant applications of 3D city models like spatial marketing, real estate management and marketing, and for visualization. The derivation of the building type from coarse data (mainly 2D footprints, building heights and functions) seems impossible at first sight. However it succeeds by incorporating the spatial context of a building. Since the input data can be derived easily and at very low cost, this method is widely applicable. Nevertheless, as with all supervised learning algorithms, obtaining labelled training data is very time-consuming. Herewith, we provide a method which uses outlier detection and clustering methods to support users in efficiently and rapidly obtaining adequate training data.     

基于地震体追踪的有序扩展算法

三维地震解释离不开三维可视化技术,对于透视图和三维可视化来说体元追踪技术是最好的技术.本文提出一种基于地震体追踪的有序扩展算法,该算法实现了数据体的三维自动追踪,是沿着真正的三维路径追踪数据体的,追踪是在纵横测线和时间方向同时进行.     

基于 BIM 和本体的建筑不规则类型审查

建筑不规则类型审查是建筑抗震审查的重要组成部分,对建筑抗震安全有重要意义。为提高审查 效率和准确性,提出一套基于建筑信息模型(BIM)和本体的建筑不规则类型审查方法。首先解析梳理建筑不规则 类型审查规范条文,然后将规范条文转译成计算机可识别的语义审查规则,并根据审查逻辑构建建筑不规则类型 审查本体;其次从待审查建筑的 BIM 文件中抽取审查信息,如楼层开洞面积,基于模板匹配算法从结构计算书 自动抽取审查所需计算结果参数,如扭转位移比;接着基于建筑不规则类型审查本体组织审查信息,利用审查规 则推理获得审查结果,进而生成审查报告。最后以某建筑为例验证了该方法的可行性和较强地扩展能力,为进一 步实现建筑抗震审查的自动化奠定了技术基础。     

自适应SRCKF在GPS动态单点定位中的应用

平方根容积卡尔曼滤波具有良好的数值稳定性与滤波效率,针对滤波中状态函数与实际不符带来的误差对滤波造成的影响,将基于预测残差统计量的自适应因子和最优自适应因子与平方根容积卡尔曼滤波算法相结合以降低预测信息在滤波中的权重,并将平方根容积卡尔曼滤波与带自适应因子的平方根容积卡尔曼滤波用于GPS动态单点定位数据处理,最后用航摄飞机实测GPS动态观测数据验证了算法的有效性。     

基于开源技术的城市地理信息平台构建方法研究

摘 要：针对城市地理信息平台构建过程中存在的数据获取困难、研发成本较高等问题， 引入开源技术，对基于开源数据、开源开发平台与开源工具的城市地理信息平台构建技术进行 研究。所提出的城市地理信息平台由数据模块与可视化模块 2 部分组成。为构建数据模块，由 开源地理信息项目(OSM)获取了建筑与区划数据，并设计了建筑合并算法以提升数据质量。建 筑数据随之基于行政区划分级存储，通过由 ASP. NET 构建的数据接口提供给具体应用。可视 化模块则基于开源地理信息系统(GIS)项目 Cesium 实现，并设计了完善的用户界面。以北京市 为例，完成了原型系统的开发与测试，证实了该技术体系的可行性，通过开源技术降低平台研 发成本，推进城市地理信息平台的研究与应用。     

An Automation System of Rooftop Detection and 3D Building Modeling from Aerial Images

This paper presents a prototype system of rooftop detection and 3D building modeling from aerial images. In this system, without the knowledge of the position and orientation information of the aerial vehicle a priori, the parameters of the camera pose and ground plane are first estimated by simple human?Ccomputer interaction. Next, after an over-segmentation of the aerial image by the Mean-Shift algorithm, the rooftop regions are coarsely detected by integrating multi-scale SIFT-like feature vectors with SVM-based visual object recognition. 2D cues alone however might not always be sufficient to separate regions such as parking lots from building roofs. Thus in order to further refine the accuracy of the roof-detection result and remove the misclassified non-rooftop regions such as parking lots, we further resort to 3D depth information estimated based on multi-view geometry. More specifically, we determine whether a candidate region is a rooftop or not according to its height information relative to the ground plane, whereas the candidate region??s height information is obtained by a novel, hierarchical, asymmetry correlation-based corner matching scheme. The output of the system will be a water-tight triangle mesh based 3D building model texture mapped with the aerial images. We developed an interactive 3D viewer based on OpenGL and C+?+ to allow the user to virtually navigate the reconstructed 3D scene with mouse and keyboard. Experimental results are shown on real aerial scenes.     

面向智慧城市的3维城市在线可视化

目的 3维城市可视化是智慧城市信息显示的基础,对城市信息的实时准确传递起着重要作用。而现有的3维城市可视化方法和系统存在两点局限性:一是数据模型不适合于海量建筑物显示;二是对整个城市采用单一绘制方式,而建筑物的纹理、结构、高度等特征相似,绘制结果容易引起视觉混淆,为此提出一种基于人类感知理论的3维城市在线可视化技术。方法在预处理阶段,系统采用建筑综合算法建立3维城市建筑物的多分辨率表示;在运行时刻,系统根据用户交互,自适应选择建筑物相应的层次进行显示。结果采用几个3维城市数据对系统进行了测试,实验结果证明,该系统有效地提高了3维城市绘制效率。Leverkusen城市的5 530座建筑物,绘制效率达到19.4帧/s。结论基于感知的3维城市多分辨率表示,有效提高了3维城市系统的显示效率以及用户获取信息的效率,同时提高了用户的交互效率。     

三维地形真实感绘制及其实时漫游

介绍了分形几何的基本原理,讨论了如何利用中点位移法生成三维分形地形高程数据模型,并在VC与OpenGL结合开发环境下,使得用尽量少的数据量来生成具有真实感的虚拟地形,以及实现交互式动态显示,能快速实时地以第一人称视角进行三维场景漫游,最后对该模型进行了验证分析,表明该方法是一种简单且有效的方法.