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191.
192.
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. 相似文献
193.
刘珊珊 《测绘与空间地理信息》2019,42(5):81-83
为满足地理国情普查数据库建设技术设计要求,全国各省市普查数据成果都需要进行全面的入库前预处理。处理过程烦琐,若采用人工方式,工作效率低下且数据质量难以保证。本文依托丰富的实际生产经验,在进一步筛选和不断总结的基础上,对地理国情普查数据预处理软件进行了主体功能设计。 相似文献
194.
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. 相似文献
195.
Christopher League 《The Cartographic journal》2019,56(2):117-133
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. 相似文献
196.
随着互联网技术的发展和“互联网+”业态的兴起,电子政务成为推进审批服务便民化的重要内容。地图审核作为一项行政许可,主要分为申请和受理、技术审查、审批和送达及样本备案4个业务环节。根据上述业务步骤,本文对地图审核在线审批系统的设计进行了分析,完成了系统的构建与应用,为同类型其他系统的构建提供了参考。 相似文献
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198.
地图集在经济建设中起着越来越重要的作用,区域地图集已成为国际上科学编图的新趋势。结合地市级区域特点,探讨了图集设计过程中的内容组织及选题思想。 相似文献
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200.
无机盐改性对沸石覆盖技术控制底泥氮磷释放的影响研究 总被引:5,自引:0,他引:5
通过试验,考察了无机盐改性对沸石覆盖控制底泥氮磷释放效果的影响,并对沸石覆盖技术控制底泥氮磷释放的机理进行初步探讨,结果表明:①NaCl及CaCl2改性对沸石吸附氨氮的性能影响不大;CaCl2改性可以提高沸石Ca2 的交换量而降低Na 的交换量,NaCl改性则可以明显降低Ca2 的交换量和增加Na 的交换量.②NaCl及CaCl2改性对沸石覆盖技术控制底泥氨氮的释放影响不大,而对控制底泥磷的释放则影响较大,沸石覆盖控制底泥磷释放效率从大到小依次为CaCl2改性沸石>天然沸石>NaCl改性沸石.③沸石覆盖技术控制底泥氨氮释放的机理为沸石的物理吸附和阳离子交换作用,控制底泥磷释放的机理包括沸石的机械阻挡作用和沸石与铵所交换出来的Ca2 对磷酸盐的固定作用. 相似文献