数字海图发行管理系统的设计与实现

为解决我国有关部门在数字海图发行中存在的数据及用户管理问题,通过对国内外现行数字海图发行管理机制的研究,提出了以海图数据封装发行模式代替目前直接复制数据的方式,开发和采用计算机软硬件结合加密的授权许可证技术,设计与实现具有可视化、集成化特点的新型的数字海图发行管理系统的方法.     

新疆塔西河石门子水库大坝变形监测初步分析研究

本文对新疆玛纳斯石门子水库大坝变形监测网的设计进行了论述,介绍了该监测网的实施方法,并对变形监测成果进行了初步的分析研究。     

城市地下管网信息系统分析

介绍城市综合管网建设必要性,着重讲述了系统的设计目标、系统设计原则、设计方案、以及利用GIS等数据格式建立综合管网信息系统。     

Observation on height changes of chinese tide gauges by GPS

IntroductionBecause of global temperature rising and glacierthawing,the sea level has risen about 10-25 cmin the past century[1]. The sea level change isone of the main ai ms in global change monito-ring. Presently the basic tool used in sea levelmonitori…     

数字海图发行管理系统的设计与实现

为解决我国有关部门在数字海图发行中存在的数据及用户管理问题,通过对国内外现行数字海图发行管理机制的研究,提出了以海图数据封装发行模式代替目前直接复制数据的方式,开发和采用计算机软硬件结合加密的授权许可证技术,设计与实现具有可视化、集成化特点的新型的数字海图发行管理系统的方法。     

狭长区域下基于正交法的GPS高程拟合研究

将GPS点大地高直接转换成正常高,越来越广泛地应用于建立高程控制网的实践中。而要保证GPS点高程精度的关键是高程异常拟合模型选择的合理性。文中介绍了在狭长带状区域下利用正交函数法拟合GPS点高程的数学模型。并利用试验数据进行比对分析。结果表明,文中提出的方法计算具有算法稳定,成果合理的特点。     

论卫星导航体制设计

阐述了卫星导航体制设计基本要素及设计原则。从卫星导航系统的发展历史及未来需求出发,提出了多功能一体化,全球卫星导航系统的基本结构,星座及卫星轨道选择,导航测距码设计及未来GNSS模式等新论点及论证结论。     

Cartographic Design and the Space–Time Cube

This paper reports on the results of an empirical evaluation that aimed to define the effectiveness and efficiency of different visual variables in depicting the Space–Time Cube’s (STC) content. Existing STC applications demonstrate that the most used visual variables are size and colour hue. Less is known, however, about their usability metrics. The research sets design criteria for STC contents, such as space–time paths, based on the cartographic design theory. The visual variables colour hue, colour value, colour saturation, size and orientation have been applied in two different use case studies. Besides, to support the three-dimensional visual environment, depth cues such as shading and transparency were considered too. User tests have been executed based on real-world problems with particular attention for the visualization strategy and data complexity. The outcomes revealed the most efficient and effective visual variables to represent data of various complexities in the STC.     

Cartographic Symbol Design Considerations for the Space–Time Cube

The cartographic representation of geographic phenomena in the space–time cube comes with special challenges and opportunities when compared with two-dimensional maps. While the added dimension allows the display of attributes that vary with time, it is difficult to display rapidly varying temporal data given the limited display height. In this study, we adapt 2D cyclic point symbols to construct 3D surfaces designed along a helical path for the space–time cube. We demonstrate how these complex?3D helical surfaces can display detailed data, including data reported daily over 100 years and data reported in four-hour intervals over a year. To create the point symbols, each value is plotted along the curve of a helix, with each turn of the helix representing one year or week, respectively. The model is modified by varying the radii from the time axis to all points using the attribute value, in these cases maximum daily temperature and four-hourly ridership, and then creating a triangulated surface from the resulting points. Using techniques common to terrain representation, we apply hue and saturation to the surface based on attribute values, and lightness based on relief shading. Multiple surfaces can be displayed in a space–time cube with a consistent time interval facing the viewer, and the surfaces or viewer perspective can be rotated to display synchronized variations. We see this method as one example of how cartographic design can refine or enhance operations in the space–time cube.     

A literature synthesis of LiDAR applications in transportation: feature extraction and geometric assessments of highways

Interest in using Light Detection and Ranging (LiDAR) technology in Transportation Engineering has grown over the past decade. The high accuracy of LiDAR datasets and the efficiency by which they can be collected has led many transportation agencies to consider mobile LiDAR as an alternative to conventional tools when surveying roadway infrastructure. Nonetheless, extracting semantic information from LiDAR datasets can be extremely challenging. Although extracting roadway features from LiDAR has been considered in previous research, the extraction of some features has received more attention than others. In fact, for some roadway design elements, attempts to extract those elements from LiDAR have been extremely scarce. To document the research that has been done in this area, this paper conducts a thorough review of existing studies while also highlighting areas where more research is required. Unlike previous research, this paper includes a thorough review of the previous attempts at data extraction from LiDAR while summarizing the detailed steps of the extraction procedure proposed in each study. Moreover, the paper also identifies common tools and techniques used to extract information from LiDAR for transportation applications. The paper also highlights common limitations in existing algorithms that could be improved in future research. This paper represents a valuable resource for researchers and practitioners interested in knowing the current state of research on the applications of LiDAR in the field of Transportation Engineering while also understanding the opportunities and challenges that lie ahead.