OpenStreetMap(OSM)is a dataset in constant change and this dynamic needs to be better understood.Based on 12-year time series of seven OSM data contribution activities extracted from 20 large cities worldwide,we inves...OpenStreetMap(OSM)is a dataset in constant change and this dynamic needs to be better understood.Based on 12-year time series of seven OSM data contribution activities extracted from 20 large cities worldwide,we investigate the temporal dynamic of OSM data production,more specifically,the auto-and cross-correlation,temporal trend,and annual seasonality of these activities.Furthermore,we evaluate and compare nine different temporal regression methods for forecasting such activities in horizons of 1–4 weeks.Several insights could be obtained from our analyses,including that the contribution activities tend to grown linearly in a moderate intra-annual cycle.Also,the performance of the temporal forecasting methods shows that they yield in general more accurate estimations of future contribution activities than a baseline metric,i.e.the arithmetic average of recent previous observations.In particular,the well-known ARIMA and the exponentially weighted moving average methods have shown the best performances.展开更多
地面站导航电子地图是操作员用来监控无人驾驶装备的唯一平台,也是进行线路规划和自主决策的重要信息源。现有的导航电子地图一般存在价格昂贵、对高程数据支持不足以及依赖互联网等缺陷。本文提出了一种新的基于OpenStreetMap的地面站...地面站导航电子地图是操作员用来监控无人驾驶装备的唯一平台,也是进行线路规划和自主决策的重要信息源。现有的导航电子地图一般存在价格昂贵、对高程数据支持不足以及依赖互联网等缺陷。本文提出了一种新的基于OpenStreetMap的地面站导航电子地图实现方法。首先,利用原始OSM数据搭建地图瓦片服务后台;然后将90 m SRTM高程数据处理成地形阴影和地形颜色渐变栅格文件;针对每个栅格文件,在瓦片服务后台的样式配置文件中添加相应图层并定义其渲染格式;最后,在地面站软件中实现地图客户端模块,向瓦片服务后台请求瓦片,并显示在地面站界面上。利用该方法实现的地面站导航电子地图可以提供0~18个缩放级别的中国范围的数据,显示0~13个缩放级别的立体地形地貌,并且无需互联网支持。本文使用该方法实现了某型无人机的地面站导航电子地图模块,并成功应用该无人机仿真系统。展开更多
A land-use map at the regional scale is a heavy computation task yet is critical to most landowners,researchers,and decision-makers,enabling them to make informed decisions for varying objectives.There are two major d...A land-use map at the regional scale is a heavy computation task yet is critical to most landowners,researchers,and decision-makers,enabling them to make informed decisions for varying objectives.There are two major difficulties in generating land classification maps at the regional scale:the necessity of large data-sets of training points and the expensive computation cost in terms of both money and time.Volunteered Geographic Information opens a new era in mapping and visualizing the physical world by providing an open-access database valuable georeferenced information collected by volunteer citizens.As one of the most well-known VGI initiatives,OpenStreetMap(OSM),contributes not only to road network distribution information but also to the potential for using these data to justify and delineate land patterns.Whereas,most large-scale mapping approaches-including regional and national scales–confuse“land cover”and“land-use”,or build up the land-use database based on modeled land cover data-sets,in this study,we clearly distinguished and differentiated land-use from land cover.By focusing on our prime objective of mapping land-use and management practices,a robust regional land-use mapping approach was developed by integrating OSM data with the earth observation remote sensing imagery.Our novel approach incorporates a vital temporal component to large-scale land-use mapping while effectively eliminating the typically burdensome computation and time/money demands of such work.Furthermore,our novel approach in regional scale land-use mapping produced robust results in our study area:the overall internal accuracy of the classifier was 95.2%and the external accuracy of the classifier was measured at 74.8%.展开更多
Natural disasters,such as wildfires,earthquakes,landslides,or floods,lead to an increase in topical information shared on social media and in increased mapping activities in volunteered geographic information(VGI)plat...Natural disasters,such as wildfires,earthquakes,landslides,or floods,lead to an increase in topical information shared on social media and in increased mapping activities in volunteered geographic information(VGI)platforms.Using earthquakes in Nepal and Central Italy as case studies,this research analyzes the effects of natural disasters on short-term(weeks)and longer-term(half year)changes in OpenStreetMap(OSM)mapping behavior and tweet activities in the affected regions.An increase of activities in OSM during the events can be partially attributed to those focused OSM mapping campaigns,for example,through the Humanitarian OSM Team(HOT).Using source tags in OSM change-sets,it was found that only a small portion of external mappers actually travels to the affected regions,whereas the majority of external mappers relies on desktop mapping instead.Furthermore,the study analyzes the spatio-temporal sequence of posted tweets together with keyword filters to identify a subset of users who most likely traveled to the affected regions for support and rescue operations.It also explores where,geographically,earthquake information spreads within social networks.展开更多
OpenStreetMap(OSM)data are widely used but their reliability is still variable.Many contributors to OSM have not been trained in geography or surveying and consequently their contributions,including geometry and attri...OpenStreetMap(OSM)data are widely used but their reliability is still variable.Many contributors to OSM have not been trained in geography or surveying and consequently their contributions,including geometry and attribute data inserts,deletions,and updates,can be inaccurate,incomplete,inconsistent,or vague.There are some mechanisms and applications dedicated to discovering bugs and errors in OSM data.Such systems can remove errors through user-checks and applying predefined rules but they need an extra control process to check the real-world validity of suspected errors and bugs.This paper focuses on finding bugs and errors based on patterns and rules extracted from the tracking data of users.The underlying idea is that certain characteristics of user trajectories are directly linked to the type of feature.Using such rules,some sets of potential bugs and errors can be identified and stored for further investigations.展开更多
Nowadays,several research projects show interest in employing volunteered geographic information(VGI)to improve their systems through using up-to-date and detailed data.The European project CAP4Access is one of the su...Nowadays,several research projects show interest in employing volunteered geographic information(VGI)to improve their systems through using up-to-date and detailed data.The European project CAP4Access is one of the successful examples of such international-wide research projects that aims to improve the accessibility of people with restricted mobility using crowdsourced data.In this project,OpenStreetMap(OSM)is used to extend OpenRouteService,a well-known routing platform.However,a basic challenge that this project tackled was the incompleteness of OSM data with regards to certain information that is required for wheelchair accessibility(e.g.sidewalk information,kerb data,etc.).In this article,we present the results of initial assessment of sidewalk data in OSM at the beginning of the project as well as our approach in awareness raising and using tools for tagging accessibility data into OSM database for enriching the sidewalk data completeness.Several experiments have been carried out in different European cities,and discussion on the results of the experiments as well as the lessons learned are provided.The lessons learned provide recommendations that help in organizing better mapping party events in the future.We conclude by reporting on how and to what extent the OSM sidewalk data completeness in these study areas have benefited from the mapping parties by the end of the project.展开更多
文摘OpenStreetMap(OSM)is a dataset in constant change and this dynamic needs to be better understood.Based on 12-year time series of seven OSM data contribution activities extracted from 20 large cities worldwide,we investigate the temporal dynamic of OSM data production,more specifically,the auto-and cross-correlation,temporal trend,and annual seasonality of these activities.Furthermore,we evaluate and compare nine different temporal regression methods for forecasting such activities in horizons of 1–4 weeks.Several insights could be obtained from our analyses,including that the contribution activities tend to grown linearly in a moderate intra-annual cycle.Also,the performance of the temporal forecasting methods shows that they yield in general more accurate estimations of future contribution activities than a baseline metric,i.e.the arithmetic average of recent previous observations.In particular,the well-known ARIMA and the exponentially weighted moving average methods have shown the best performances.
文摘地面站导航电子地图是操作员用来监控无人驾驶装备的唯一平台,也是进行线路规划和自主决策的重要信息源。现有的导航电子地图一般存在价格昂贵、对高程数据支持不足以及依赖互联网等缺陷。本文提出了一种新的基于OpenStreetMap的地面站导航电子地图实现方法。首先,利用原始OSM数据搭建地图瓦片服务后台;然后将90 m SRTM高程数据处理成地形阴影和地形颜色渐变栅格文件;针对每个栅格文件,在瓦片服务后台的样式配置文件中添加相应图层并定义其渲染格式;最后,在地面站软件中实现地图客户端模块,向瓦片服务后台请求瓦片,并显示在地面站界面上。利用该方法实现的地面站导航电子地图可以提供0~18个缩放级别的中国范围的数据,显示0~13个缩放级别的立体地形地貌,并且无需互联网支持。本文使用该方法实现了某型无人机的地面站导航电子地图模块,并成功应用该无人机仿真系统。
文摘A land-use map at the regional scale is a heavy computation task yet is critical to most landowners,researchers,and decision-makers,enabling them to make informed decisions for varying objectives.There are two major difficulties in generating land classification maps at the regional scale:the necessity of large data-sets of training points and the expensive computation cost in terms of both money and time.Volunteered Geographic Information opens a new era in mapping and visualizing the physical world by providing an open-access database valuable georeferenced information collected by volunteer citizens.As one of the most well-known VGI initiatives,OpenStreetMap(OSM),contributes not only to road network distribution information but also to the potential for using these data to justify and delineate land patterns.Whereas,most large-scale mapping approaches-including regional and national scales–confuse“land cover”and“land-use”,or build up the land-use database based on modeled land cover data-sets,in this study,we clearly distinguished and differentiated land-use from land cover.By focusing on our prime objective of mapping land-use and management practices,a robust regional land-use mapping approach was developed by integrating OSM data with the earth observation remote sensing imagery.Our novel approach incorporates a vital temporal component to large-scale land-use mapping while effectively eliminating the typically burdensome computation and time/money demands of such work.Furthermore,our novel approach in regional scale land-use mapping produced robust results in our study area:the overall internal accuracy of the classifier was 95.2%and the external accuracy of the classifier was measured at 74.8%.
文摘Natural disasters,such as wildfires,earthquakes,landslides,or floods,lead to an increase in topical information shared on social media and in increased mapping activities in volunteered geographic information(VGI)platforms.Using earthquakes in Nepal and Central Italy as case studies,this research analyzes the effects of natural disasters on short-term(weeks)and longer-term(half year)changes in OpenStreetMap(OSM)mapping behavior and tweet activities in the affected regions.An increase of activities in OSM during the events can be partially attributed to those focused OSM mapping campaigns,for example,through the Humanitarian OSM Team(HOT).Using source tags in OSM change-sets,it was found that only a small portion of external mappers actually travels to the affected regions,whereas the majority of external mappers relies on desktop mapping instead.Furthermore,the study analyzes the spatio-temporal sequence of posted tweets together with keyword filters to identify a subset of users who most likely traveled to the affected regions for support and rescue operations.It also explores where,geographically,earthquake information spreads within social networks.
基金This research was supported financially by EU FP7 Marie Curie Initial Training Network MULTI-POS(Multi-technology Positioning Professionals)[grant number 316528].
文摘OpenStreetMap(OSM)data are widely used but their reliability is still variable.Many contributors to OSM have not been trained in geography or surveying and consequently their contributions,including geometry and attribute data inserts,deletions,and updates,can be inaccurate,incomplete,inconsistent,or vague.There are some mechanisms and applications dedicated to discovering bugs and errors in OSM data.Such systems can remove errors through user-checks and applying predefined rules but they need an extra control process to check the real-world validity of suspected errors and bugs.This paper focuses on finding bugs and errors based on patterns and rules extracted from the tracking data of users.The underlying idea is that certain characteristics of user trajectories are directly linked to the type of feature.Using such rules,some sets of potential bugs and errors can be identified and stored for further investigations.
基金supported by the European Community’s Seventh Framework Programme[FP7/2007–2013],[Grant No 612096(CAP4Access)].
文摘Nowadays,several research projects show interest in employing volunteered geographic information(VGI)to improve their systems through using up-to-date and detailed data.The European project CAP4Access is one of the successful examples of such international-wide research projects that aims to improve the accessibility of people with restricted mobility using crowdsourced data.In this project,OpenStreetMap(OSM)is used to extend OpenRouteService,a well-known routing platform.However,a basic challenge that this project tackled was the incompleteness of OSM data with regards to certain information that is required for wheelchair accessibility(e.g.sidewalk information,kerb data,etc.).In this article,we present the results of initial assessment of sidewalk data in OSM at the beginning of the project as well as our approach in awareness raising and using tools for tagging accessibility data into OSM database for enriching the sidewalk data completeness.Several experiments have been carried out in different European cities,and discussion on the results of the experiments as well as the lessons learned are provided.The lessons learned provide recommendations that help in organizing better mapping party events in the future.We conclude by reporting on how and to what extent the OSM sidewalk data completeness in these study areas have benefited from the mapping parties by the end of the project.
