机载激光雷达技术在地质灾害调查中的应用——以四川九寨沟7.0级地震为例

九寨沟7.0级地震诱发的地质灾害具有高位滑坡远程灾害的特点,传统地质灾害排查手段无法有效解决隐患的早期识别问题。本文采用机载激光雷达测量技术,快速获取九寨沟地震核心景区的激光点云数据。通过构建高精度数字高程模型(DEM)、数字正射影像图(DOM),建立三维地质灾害解译场景,利用数字地形分析、地形形态学分析和计算机图像识别等技术,综合开展九寨沟高位远程区域内隐蔽性强、随机性大的地质灾害隐患早期识别与分析。应用实践表明,机载激光雷达测量技术可以提高九寨沟地震灾区地质灾害隐患的早期识别能力,对进一步提高综合防灾减灾能力提供了一些可借鉴的思路。     

A building label placement method for 3D visualizations based on candidate label evaluation and selection

Adding building labels greatly improves the recognizability of buildings and the readability of three-dimensional (3D) city scenes. However, building label placement is much more complex in 3D scenes than in two-dimensional (2D) maps. The annotation effect is influenced by the attributes of the 3D label, building visibility, and the spatial relationship between the building and viewpoint. In this context, automatically generating building labels for 3D scenes during interactions requires highly complex computations. By contrast, evaluating candidate labels and then selecting the suitable label for each building can be effectively implemented. This paper introduces an approach for labeling buildings in 3D scenes based on evaluations of label candidates. The proposed method predefines a candidate label set for each building. These candidates are then evaluated in terms of their attributes and the relationship between the labels and viewpoint at runtime. The best candidate label, or a situational alternative for each building, is then placed in order of comprehensive label priority to avoid annotation conflicts. A series of experiments demonstrate that this method effectively enhances the correlation of labels and buildings, improves interactive efficiency, and realizes a viable global label layout.     

基于3S集成技术的土地调查系统实践

为准确掌握土地资源信息,目前已经开始进行全国第二次士地调查工作.近年来空间信息技术得到迅速发展,为土地调查提供了新的技术方法.针对传统土地调查作业现势性差和周期长等问题,提出一种基于RS与移动GIS集成的土地调查系统.在阐述系统作业流程的基础上,详细介绍系统在权属界线调查、地类调查和地类补测中的应用方法与试验.经试验应用证明,利用奉系统能够提高劳动敏率与降低劳动强度,大幅提高精度,是一种应用前景广阔的技术方法.     

烷烃与海水界面张力的研究

于１９９１年３月－１９９２年６月间用滴体积法较系统地测定正已烷、正庚烷、正辛烷、异辛烷、正十二烷、正十六烷和煤油与海水在不同的温度（１６－４０℃）和盐度（１０－４０）范围内的界面张力，测定值的相对误差≤０．５％。对数据进行统计处理后，归纳出所研究烷烃－海水界面张力与温度和盐度的经验关系式，计算与实验值相对误差≤０．５％。     

Metallogenic focus-area and superlarge mineral deposits in the bordering zones between China,Russia and Mongolia

A correlative study of geology and metallogenic process in the bordering zones between China, Russia and Mongolia shows that the region of the western slope of the Da Hingan Mts. -Eastern Transbaikalia-Eastern Mongolia is a metallogenic focus-area associated with Late Mesozoic intraplate tectono-magmatic activation. During the period of 160–120 Ma a great number of multiplex deposits with similar genesis including large and superlarge mineral deposits were formed.

     

四川省剑门关一带晚侏罗世沉积体系与古环境演化

晚侏罗世是龙门山前陆盆地演化的关键时期, 因而沉积体系与古环境演化研究具有重要意义.运用比较沉积学的方法, 通过对沉积序列与旋回的详细研究, 将研究区晚侏罗世沉积体系分为湖泊沉积体系、三角洲沉积体系、冲积扇沉积体系以及河流沉积体系; 基于沉积背景和演化的分析, 确定龙门山推覆构造带是研究区晚侏罗世古环境演化和沉积体系空间配置的控制因素; 依据古流和物源分析, 确定西北部的龙门山是本区主要物源区      

黄河三角洲饱和粉土液化特性及孔压模型试验研究

以黄河三角洲地区可液化场地粉土为研究对象,利用室内循环三轴试验结果,分析了动荷载作用下粉土的液化特性,通过模拟地震荷载作用下粉土的孔压响应,提出了原状粉土的孔压上升模型,并与粉质粘土和粉砂的液化特性和孔压模型进行了对比,并得出一些结论。     

Crowd sensing and spatiotemporal analysis in urban open space using multi-viewpoint geotagged videos

Increasing concern for urban public safety has motivated the deployment of a large number of surveillance cameras in open spaces such as city squares, stations, and shopping malls. The efficient detection of crowd dynamics in urban open spaces using multi-viewpoint surveillance videos continues to be a fundamental problem in the field of urban security. The use of existing methods for extracting features from video images has resulted in significant progress in single-camera image space. However, surveillance videos are geotagged videos with location information, and few studies have fully exploited the spatial semantics of these videos. In this study, multi-viewpoint videos in geographic space are used to fuse object trajectories for crowd sensing and spatiotemporal analysis. The YOLOv3-DeepSORT model is used to detect a pedestrian and extract the corresponding image coordinates, combine spatial semantics (such as the positions of the pedestrian in the field of view of the camera) to build a projection transformation matrix and map the object recorded by a single camera to geographic space. Trajectories from multi-viewpoint videos are fused based on the features of location, time, and directions to generate a complete pedestrian trajectory. Then, crowd spatial pattern analysis, density estimation, and motion trend analysis are performed. Experimental results demonstrate that the proposed method can be used to identify crowd dynamics and analyze the corresponding spatiotemporal pattern in an urban open space from a global perspective, providing a means of intelligent spatiotemporal analysis of geotagged videos.