GIS空间数据几何变换的不确定性传播

针对点位误差、线元在对称、旋转变换过程中不确定性的传播规律,该文采用误差椭圆和εm模型描述GIS空间数据对象模型中最常用的点、线元素的误差域,讨论几何变换(如对称、旋转变换)过程中不确定性的积累和传播规律,结合区间算法给出了变换后误差域模型。基于区间运算的INTLAB模拟结果验证了该模型的有效性和实用性。研究结果对进一步探讨其他几何变换过程中不确定性的积累传播规律具有一定参考。     

A power-law-based approach to mapping COVID-19 cases in the United States

This paper examines the spatial and temporal distribution of all COVID-19 cases from January to June 2020 against the underlying distribution of population in the United States. It is found that, as time passes, COVID-19 cases become a power law with cutoff, resembling the underlying spatial distribution of populations. The power law implies that many states and counties have a low number of cases, while only a few highly populated states and counties have a high number of cases. To further differentiate patterns between the underlying populations and COVID-19 cases, we derived their inherent hierarchy or spatial heterogeneity characterized by the ht-index. We found that the ht-index of COVID-19 cases persistently approaches that of the populations; that is, 5 and 7 at the state and county levels, respectively. Mapping the ht-index of COVID-19 cases against that of populations shows that the pandemic is largely shaped by the underlying population with the R-square value between infection and population up to 0.82.     

山东省新型冠状病毒肺炎时空特征研究

利用描述性统计和空间分析方法研究山东省2020-01-21～2020-03-11新冠肺炎时空特征.山东省共有99个区县出现确诊病例,疫情总体呈东部和南部较重、北部较轻的空间分布特征;整体病例和本土病例无空间集聚性,输入病例存在空间集聚性,输入病例的空间集聚分布并不完全遵循与湖北省地理邻近特征;鲁东、鲁中和鲁南地区疫情扩...     

温州市新型冠状病毒肺炎时空分布格局演化分析

本文首先结合社交媒体信息和温州市新型冠状病毒肺炎（COVID-19）发展态势,获取疫情传播先验知识,进一步采用DBSCAN自适应聚类算法,分析温州市COVID-19时空分布格局与演化规律。结果表明：①温州市COVID-19易在20~59岁的青壮年人群,以及商业服务人员、农民和工人人群间传播;②我国针对人口流动采取的系列措施能够有效遏制疫情进一步蔓延,使得温州市聚类空间簇数量在时间上呈现先增加后减小的趋势;③温州市鹿城区银泰商贸附近、乐清市南部和瑞安市西部具有疫情扩散高风险,后期需增强防控力度。本文细粒度地分析了温州市疫情时空演化过程,能够更好地辅助温州市政府部门更精细地部署疫情防控措施。     

新冠疫情期间中国人为碳排放和大气污染物的变化

为了探究突发公共卫生事件期间人类活动减少对中国空气质量的影响,分析了气溶胶光学厚度(aerosol optical depth, AOD)、大气可降水量(precipitable water vapor, PWV)和气温(temperature, T)的时空异常变化,揭示了人类活动对空气质量的影响。首先,与气溶胶自动观测网(aerosol robotic network, AERONET)提供的AOD和无线电探空仪提供的PWV和T数据对比,验证使用的AOD、PWV和T的精度。其次,分析周末与周内期间AOD、PWV和T的长时序变化趋势,发现人类活动对空气质量有一定影响。然后,研究突发公共卫生事件期间AOD、PWV和T的时空变化,证实人类活动与空气质量有较好的相关性。最后,选取中国184个不同等级的城市进行进一步分析,确定人口密度对AOD、PWV和T的影响程度,进一步揭示了人类活动与空气质量的具体响应关系。

     

The effect of spatial distance on the discriminability of colors in maps

ABSTRACT

The spatial distance (gap) between map symbols can have a great impact on their discriminability, however, there is little empirical evidence to establish spatial and attribute thresholds. In this paper, we examine the effect of the spatial gap in discriminability of color hue and value, that is, we conducted an online study to obtain performance metrics; then an eye-tracking study to understand participants’ strategies and cognitive processes. Participants completed two experimental tasks (compare two areas and decide if their color is the same; and compare three areas and rank them from the lightest to the darkest). The color distances and the spatial distances were strictly controlled for the compared areas. Our analyses confirmed that, overall, increasing the gap between colors has a consistent negative impact on the ability to differentiate them with both sequential and qualitative schemes. Furthermore, we observed that sequential schemes require larger color distances than qualitative schemes for discriminability. Finally, our results suggested that for qualitative colors, the largest tested color distance ?E₀₀ = 10 yields considerably higher levels of accuracy in color discrimination (even when the spatial gap between the two colors is large), thus we recommend ?E₀₀ = 10 to practicing cartographers and other information visualization designers.     

温州市新型冠状病毒肺炎疫情扩散时空特征研究

新型冠状病毒肺炎(COVID-19)疫情爆发以来,温州市疫情形势严峻.本文通过温州市卫生健康委员会官方网站公布的新型冠状病毒肺炎患者的具体信息,利用数据分析法、GIS技术和定量分析法对温州市新冠肺炎疫情的发展变化、分布及扩散特征进行分析.结果显示:1)温州市新冠肺炎确诊病例男性占比高于女性,且以中青年人为主,老年人位列...     

Constraints of progressive transmission of spatial data on the web

The progressive transmission of map data on the World Wide Web provides the user with a self-adaptive strategy to access remote data. It not only speeds up the web transfer but also offers an efficient navigation guide for information acquisition. The key technology in this transmission is the efficient multiple representation of spatial data and pre-organization on the server site. This paper aims at progressive transmission investigating some constraints from three aspects: data organization on server site, data control in the transmission process and data restore after reaching the client. Two strategies, namely on-line map generalization and off-line map generalization, are examined respectively for this kind of progressive transmission.     

北京市新冠肺炎疫情信息平台的设计与实现

基于SuperMap iServer平台和天地图底图服务,建立北京市新冠肺炎疫情信息平台,通过将疫情信息细化到街道、乡、镇级别,实现了北京市疫情中高风险地区图、各区无新增病例分布图、各区累计本地确诊病例分布图、确诊病例市场分布图和核酸检测机构分布图等五类专题的查询和展示.通过建立每日更新的机制,及时向社会公众发布疫情信...     

在特殊疫情背景下《城市地理资讯学》MOOC课程教学实施效果分析

在新冠肺炎疫情期间,线上教学大规模开展,相关线上教学问题逐渐成为研究热点.传统的测绘地理类课程的教学方式主要是上课时以老师传授知识为主,课后以学生完成作业为辅的方式进行.但是,这种教学方式比较单一,并且在科学化考核和促进学生学习主动性等方面存在诸多问题.然而,线上网络课程是通过互联网以电子设备为教学平台,具有不受教学时...     

改进的无人机影像处理技术在新冠疫情复工建设中的应用

疫情期间复工复产需要准确的现场信息及高精度分辨率的正射影像作为决策依据,但管理人员无法通过密集的现场巡视获取信息。无人机外业数据采集速度快、采集精度高、数据量全,但传统的无人机正射影像处理速度无法满足项目刻不容缓的需求,因此本文对无人机外业快速采集-快速内业处理技术-目标成果识别作了全方位的研究,基于改进SURF无人机影像快速处理算法并针对大型工程设备在影像上呈现规则矩形、特征点突出、明暗对比关系明显等关键要素,快速处理得到正射影像,并在此基础上运用Fast R-CNN网络识别现场机械设备为复工决策提供决策依据,相应成果已在新冠疫情期间雄安高铁站工程建设复工复产中得到了应用。     

新冠病毒疫情期间复工复产卫星遥感监测

本文利用美国新一代极轨卫星NPP搭载的VIIRS载荷数据反演获得的热点数据,以及美国NASA的Aura卫星搭载的OMI载荷的二氧化氮对流层柱浓度资料,对中国地区2020-01—02及2019年同期,以及抗击疫情期间和后期复工复产的情况进行监测。监测结果表明：（1）2020-02较1月份及2019年同期相比,工业企业的耗能水平却出现显著降低,NO₂浓度呈现显著下降趋势。（2）全国工业热源点数和分布范围及密度自2020-02-03正式复工后稳步提升。湖北省除武汉、黄石和鄂州地区仍可监测到少数热点外,其他地区2月份均未再监测到任何热点,也证明了湖北基本没有复工迹象。（3）疫情得到基本控制之后,京津冀地区工业热源点有显著增加,但新增区域一般仍处于低能耗水平。从全国大气NO₂柱浓度监测来看,复工开始前后与2019年同期相比,污染物浓度均呈现明显下降趋势,说明复工强度有限。（4）到3月初工业热源点及其能耗水平出现显著升高,中国大部分地区的热源企业虽已逐步复工生产,说明工业产能较2月有显著提升,但生产规模或产能并未完全恢复。     

疫情背景下学生外出避险导航系统设计与实现

为了响应国家疫情常态化管理要求,弥补疫情背景下高校对于学生外出管理办法的缺陷。本文结合安卓（Android）开发、万维网（Web）开发、网络编程、派森（Python）爬虫技术设计并实现了一套疫情背景下学生外出避险导航系统。该系统能实时生成多尺度疫情风险地图,动态跟踪外出学生位置,自动划分疫情高风险区域并设置疫情围栏。系统主体部分为Android平台和Web平台,针对用户分别为学生和高校管理人员。Android平台负责获取学生出行数据,并包含出校扫码、轨迹记录、危险区域警告、避险导航、疫情风险地图等功能,Web平台负责接收管理学生数据,进行数据统计与分析。学生可以利用手机应用程序（APP）合理规划出行路线,在出现危险行为时发送提醒并根据危险级别向Web平台发送警告,提醒管理者采取措施。本系统在辅助学生安全外出的同时,也有效地帮助了高校对学生外出的管理工作。     

新型冠状病毒肺炎期间公众情感的时空演化分析

新型冠状病毒肺炎(corona virus disease 2019,COVID-19)严重影响了人们日常的工作和生活,引起了社会媒体的高度关注.基于此,本文选取青岛市为研究区域,运用Pearson相关性分析、核密度分析、百度人工智能(artificial intelligence,AI)情感分析及词频-逆文档频率算法...     

长株潭COVID-19疫情时空演化与传播趋势分析

利用本体建模的方法构建城镇公共安全事件链模型和传染病事件链传播模型,分析传染病事件的发生对社会生活和工作的影响,并选择典型案例分析其感染过程及原因,最后对新冠病例在长株潭地区的时空扩散特征以及在各县区疫情传播和变动的空间差异进行分析.结果表明:①长株潭各县区的疫情扩散格局和综合风险格局存在显著差异.主城区的扩散风险较高...     

Spatial-temporal modeling of initial COVID-19 diffusion: The cases of the Chinese Mainland and Conterminous United States

COVID-19 outbreaks in China in late December 2019, then in the United States (US) in early 2020. In the initial wave of diffusion, the virus respectively took 14 and 33 days to spread across the provinces/states in the Chinese mainland and the coterminous US, during which there are 43％ and 70％ zero entries in the space-time series for China and US respectively, indicating a zero-inflated count process. A logistic growth curve as a function of the number of days since the first case appeared in each of these countries accurately portrays the national aggregate per capita rates of infection for both. This paper presents two space-time model specifications, one based upon the generalized linear mixed model, and the other upon Moran eigenvector space-time filtering, to describe the spread of COVID-19 in the initial 19 and 58 days across the Chinese mainland and the coterminous US, respectively. Results from these case studies show both models shed new light on the role of spatial structures in COVID-19 diffusion, models that can forecast new cases in subsequent days. A principal finding is that describing the spatio- temporal diffusion of COVID-19 benefits from including a hierarchical structural component to supplement the commonly employed contagion component.     

疫情时期下的新疆旅游电子地图设计与制作

疫情期间如何通过旅游电子地图的形式,实现景区、景点的地图展示、位置信息查询和旅游线路规划,保证公众通过互联网络进行线上旅游体验,是公众的迫切需求.本文基于新疆旅游资源数据,通过核密度空间模型,分析了旅游资源的空间集聚特征;根据旅游资源中景区、景点的资源禀赋特征,进行景观美学价值重要度评估,实现旅游景区、景点的美景度分级;运用电子地图制图的理论和技术,根据旅游资源的空间集聚特征和景区、景点的美景度特征,深入探讨旅游资源电子地图的多尺度分层、符号注记设计、色彩渲染原则,提出新疆旅游资源电子地图的制作流程和方法,试图通过科学的分析进行地图要素的分层显示,为后期电子地图系统的制作提供理论研究依据.     

COVID-19疫情初期美国城市夜间灯光时空变化分析

为应对COVID-19疫情而采取的非药物干预措施显著改变了城市社会经济活动,但其变化特征和时空模式仍不明确。本研究以美国20个大城市为例,获取NPP-VIIRS月度合成数据分析2020年2—4月COVID-19疫情初期城市夜光亮度变化的空间格局、衰减特征和用地类型差异。结果表明,疫情防控措施导致美国城市夜光亮度普遍变暗,平均降低5%—8%。夜光变化呈现明显“中心—边缘”空间结构特征,夜光降低幅度随到城市中心距离增加而减小。不同用地类型夜光变化幅度存在差异,纽约居住用地和航空设施用地夜光亮度降低幅度最明显,分别下降12%和11%。芝加哥各类用地夜光亮度普遍下降20%左右,除体育设施用地外,其他各类用地夜光亮度一个月后有所恢复。夜光遥感有效反映了城市社会经济活动变化,在监测评估突发事件社会影响方面具有重要应用。     

城市空间结构对城市热环境时空异质性分布影响研究EI北大核心CSCD

城市热岛效应,即城区温度高于周边农村的现象,对社会、经济、环境和人类健康等产生诸多负面影响,全面探究影响城市热环境的驱动机制对于城市可持续发展有着重要意义。论文以吉林省长春市为例,综合利用多源遥感、气象站点、无人机测温、统计资料等数据,构建长春市城市精细化三维空间结构数据集和三维热环境数据库;使用定性与定量结合的方法,通过空间分析、三维模拟、统计分析等手段系统探讨了城市空间三维结构对于城市热环境时空异质性分布的影响;主要内容如下。     

The effect of acquisition error and level of detail on the accuracy of spatial analyses

There has been a great deal of research about errors in geographic information and how they affect spatial analyses. A typical GIS process introduces various types of errors at different stages, and such errors usually propagate into errors in the result of a spatial analysis. However, most studies consider only a single error type thus preventing the understanding of the interaction and relative contributions of different types of errors. We focus on the level of detail (LOD) and positional error, and perform a multiple error propagation analysis combining both types of error. We experiment with three spatial analyses (computing gross volume, envelope area, and solar irradiation of buildings) performed with procedurally generated 3D city models to decouple and demonstrate the magnitude of the two types of error, and to show how they individually and jointly propagate to the output of the employed spatial analysis. The most notable result is that in the considered spatial analyses the positional error has a much higher impact than the LOD. As a consequence, we suggest that it is pointless to acquire geoinformation of a fine LOD if the acquisition method is not accurate, and instead we advise focusing on the accuracy of the data.