Finding the shortest path through open spaces is a well-known challenge for pedestrian routing engines.A common solution is routing on the open space boundary,which causes in most cases an unnecessarily long route.A p...Finding the shortest path through open spaces is a well-known challenge for pedestrian routing engines.A common solution is routing on the open space boundary,which causes in most cases an unnecessarily long route.A possible alternative is to create a subgraph within the open space.This paper assesses this approach and investigates its implications for routing engines.A number of algorithms(Grid,Spider-Grid,Visibility,Delaunay,Voronoi,Skeleton)have been evaluated by four different criteria:(i)Number of additional created graph edges,(ii)additional graph creation time,(iii)route computation time,(iv)routing quality.We show that each algorithm has advantages and disadvantages depending on the use case.We identify the algorithms Visibility with a reduced number of edges in the subgraph and Spider-Grid with a large grid size to be a good compromise in many scenarios.展开更多
When a disaster emerges,timely acquisition of information is crucial for a rapid situation assessment.Although automation in the stan-dard satellite-based emergency mapping workflow has been advanced,delays still occu...When a disaster emerges,timely acquisition of information is crucial for a rapid situation assessment.Although automation in the stan-dard satellite-based emergency mapping workflow has been advanced,delays still occur at crucial steps.In order to speed up the provision of satellite-based crisis products to emergency man-agers,this paper proposes a geo-social media-based approach that detects disaster events based on the spatio-temporal analysis of georeferenced,disaster-related Tweets.The proposed methodol-ogy is validated on the basis of two use cases:wildfires in Chile and British Columbia.The results show the general ability of Twitter to forecast events several days in advance,at least for the Chile use case.However,there are large spatial differences,as there is a correlation between population density and the reliability of Twitter data.Consequently,only few meaningful alerts could be generated for British Columbia,an area with very low population numbers.展开更多
The advancements of sensing technologies,including remote sensing,in situ sensing,social sensing,and health sensing,have tremendously improved our capability to observe and record natural and social phenomena,such as ...The advancements of sensing technologies,including remote sensing,in situ sensing,social sensing,and health sensing,have tremendously improved our capability to observe and record natural and social phenomena,such as natural disasters,presidential elections,and infectious diseases.The observations have provided an unprecedented opportunity to better understand and respond to the spatiotemporal dynamics of the environment,urban settings,health and disease propagation,business decisions,and crisis and crime.Spatiotemporal event detection serves as a gateway to enable a better understanding by detecting events that represent the abnormal status of relevant phenomena.This paper reviews the literature for different sensing capabilities,spatiotemporal event extraction methods,and categories of applications for the detected events.The novelty of this review is to revisit the definition and requirements of event detection and to layout the overall workflow(from sensing and event extraction methods to the operations and decision-supporting processes based on the extracted events)as an agenda for future event detection research.Guidance is presented on the current challenges to this research agenda,and future directions are discussed for conducting spatiotemporal event detection in the era of big data,advanced sensing,and artificial intelligence.展开更多
Security has recently become a major concern in distributed geo-infrastructures for spatial data provision.Thus,a lightweight approach for securing distributed low-power environments such as geo-sensor networks is nee...Security has recently become a major concern in distributed geo-infrastructures for spatial data provision.Thus,a lightweight approach for securing distributed low-power environments such as geo-sensor networks is needed.The first part of this article presents a survey of current security mechanisms for authentication and authorisation.Based on this survey,a lightweight and scalable token-based security infrastructure was developed,which is tailored for use in distributed geo-web service infrastructures.The developed security framework comprises dedicated components for authentication,rule-based authorisation and optimised storage and administration of access rules.For validation purposes,a prototypical implementation of the approach has been created.展开更多
In the spatial design fields such as architectural design and urban design, a consensus-building process among a variety of stakeholders like project executors, architects, residents, users, and general citizens is re...In the spatial design fields such as architectural design and urban design, a consensus-building process among a variety of stakeholders like project executors, architects, residents, users, and general citizens is required. New technological developments such as cloud computing and Virtual Design Studios （VDS） enable the creation of virtual meeting systems. This paper proposes an approach towards a synchronous distributed design meeting system. In this paper, in addition to sharing a 3D virtual space for a synchronous distributed type design meeting, we developed a prototype system that enables participants to sketch or make annotations and have discussions as well as add viewpoints to them. We applied these functions to evaluate an architectural design and urban landscape examination. In conclusion, the proposed method was evaluated as being effective and feasible. Yet, it shows a few shortcomings including the fact that simultaneous operation is limited to one client, and more arbitrary shapes should be supported in future versions of the application.展开更多
基金supported by European Commission[grant number 612096(CAP4Access)].
文摘Finding the shortest path through open spaces is a well-known challenge for pedestrian routing engines.A common solution is routing on the open space boundary,which causes in most cases an unnecessarily long route.A possible alternative is to create a subgraph within the open space.This paper assesses this approach and investigates its implications for routing engines.A number of algorithms(Grid,Spider-Grid,Visibility,Delaunay,Voronoi,Skeleton)have been evaluated by four different criteria:(i)Number of additional created graph edges,(ii)additional graph creation time,(iii)route computation time,(iv)routing quality.We show that each algorithm has advantages and disadvantages depending on the use case.We identify the algorithms Visibility with a reduced number of edges in the subgraph and Spider-Grid with a large grid size to be a good compromise in many scenarios.
基金funding from the European Commission-European Union under HORIZON EUROPE(HORIZON Research and Innovation Actions)under grant agreement 101093003(HORIZON-CL4-2022-DATA-01-01)。
文摘When a disaster emerges,timely acquisition of information is crucial for a rapid situation assessment.Although automation in the stan-dard satellite-based emergency mapping workflow has been advanced,delays still occur at crucial steps.In order to speed up the provision of satellite-based crisis products to emergency man-agers,this paper proposes a geo-social media-based approach that detects disaster events based on the spatio-temporal analysis of georeferenced,disaster-related Tweets.The proposed methodol-ogy is validated on the basis of two use cases:wildfires in Chile and British Columbia.The results show the general ability of Twitter to forecast events several days in advance,at least for the Chile use case.However,there are large spatial differences,as there is a correlation between population density and the reliability of Twitter data.Consequently,only few meaningful alerts could be generated for British Columbia,an area with very low population numbers.
基金supported by NSF[CNS 1841520 and ACI 1835507]NASA Goddard[80NSSC19P2033]the NSF Spatiotemporal I/UCRC IAB members.
文摘The advancements of sensing technologies,including remote sensing,in situ sensing,social sensing,and health sensing,have tremendously improved our capability to observe and record natural and social phenomena,such as natural disasters,presidential elections,and infectious diseases.The observations have provided an unprecedented opportunity to better understand and respond to the spatiotemporal dynamics of the environment,urban settings,health and disease propagation,business decisions,and crisis and crime.Spatiotemporal event detection serves as a gateway to enable a better understanding by detecting events that represent the abnormal status of relevant phenomena.This paper reviews the literature for different sensing capabilities,spatiotemporal event extraction methods,and categories of applications for the detected events.The novelty of this review is to revisit the definition and requirements of event detection and to layout the overall workflow(from sensing and event extraction methods to the operations and decision-supporting processes based on the extracted events)as an agenda for future event detection research.Guidance is presented on the current challenges to this research agenda,and future directions are discussed for conducting spatiotemporal event detection in the era of big data,advanced sensing,and artificial intelligence.
基金This work has been funded by the European Commission(FP7 project GENESIS,reference No.223996)the Austrian Federal Ministry for Science and ResearchThe au。
文摘Security has recently become a major concern in distributed geo-infrastructures for spatial data provision.Thus,a lightweight approach for securing distributed low-power environments such as geo-sensor networks is needed.The first part of this article presents a survey of current security mechanisms for authentication and authorisation.Based on this survey,a lightweight and scalable token-based security infrastructure was developed,which is tailored for use in distributed geo-web service infrastructures.The developed security framework comprises dedicated components for authentication,rule-based authorisation and optimised storage and administration of access rules.For validation purposes,a prototypical implementation of the approach has been created.
文摘In the spatial design fields such as architectural design and urban design, a consensus-building process among a variety of stakeholders like project executors, architects, residents, users, and general citizens is required. New technological developments such as cloud computing and Virtual Design Studios （VDS） enable the creation of virtual meeting systems. This paper proposes an approach towards a synchronous distributed design meeting system. In this paper, in addition to sharing a 3D virtual space for a synchronous distributed type design meeting, we developed a prototype system that enables participants to sketch or make annotations and have discussions as well as add viewpoints to them. We applied these functions to evaluate an architectural design and urban landscape examination. In conclusion, the proposed method was evaluated as being effective and feasible. Yet, it shows a few shortcomings including the fact that simultaneous operation is limited to one client, and more arbitrary shapes should be supported in future versions of the application.
