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	An Event Oriented Approach for Spatial Temporal Data
	Huang Zhaoqiang ; Chen Xiuwan ; Zhang Xianfeng ; Sui Jianbo
	2006
关键词	event oriented spatial temporal data model petrinet query language
英文摘要	Time is a key property for geographical information and a basic dimension for comprehending and modelling space. Evolution of geographical phenomena experiences its past state, present state, its change from one to other state or object and events between two sequence state or objects. It is needed to explicitly represent all of elements and their relationships in TGIS. Up to now, the simulation of spatial dynamic processes of geographical phenomena has been presented in many studies and it is a current topic of research, whether objects or fields. In this paper, firstly, it introduces Petri-Net and analyses it's working theory. A Petri net is a graphical and mathematical modeling tool. It consists of places, transitions, and arcs that connect places with transitions. Input arcs connect places with transitions, while output arcs start at a transition and end at a place. Places can contain tokens; the current state of the modeled system (the marking) is given by the number (and type if the tokens are distinguishable) of tokens in each place. Transitions are active components. They model activities which can occur (the transition fires), thus changing the state of the system (the marking of the Petri net). Transitions are only allowed to fire if they are enabled, which means that all the preconditions for the activity must be fulfilled (there are enough tokens available in the input places). When the transition fires, it removes tokens from its input places and adds some at all of its output places. In this paper the number of token is one and only one. The place is like as the state of object, while transition is like as happenings. So it considers that object entity and happenings are the same important entities during our cognizing process for dynamic geographical phenomena, A state of spatial object connects directly to the event causing the object change and the event connects directly to another state of spatial object. There is an event between two states of spatial object or two sequence objects, and it is not allowed that two states Of spatial objects connects directly. Secondly, the paper discusses the essence of event and the relationships between event and object, event and event. The paper investigates the hierarchy of event and the scale of event. Event is composed by atomic events. From an ontological point of view, an initial distinction can be made between entities existing in the world either as continuants or occurrents. And from an information system perspective, continuants and occurrents that have a unique identity in the system are referred to as objects and events. Objects and events are both needed to model a fully dynamic system. Based on Petri-Net, the paper considers the object as place and the event as transition. Then the paper explicitly represents the state of object and the event causing the change of object. And this paper presents a conceptual model for spatial temporal data based on Petri-Net. Objects certainly change through events and events cause objects change, Objects and events are linked by pointer and identity. And they are based on the same spatial temporal environment. They are restricted each other and represent the dynamic geographical phenomena all together. Thirdly, in this section, the research is about the spatial temporal query of event-oriented for dynamic system. The spatio-temporal query is the key problem in spatial temporal data model. Some question, such as 'when does the object change and what causes it change' and 'how does the object change', is queried for some certain requirement. So it is needed to develop spatio-temporal query for spatial temporal processing. The paper presents an improved time parameterized queries method. And utilizing R-tree, the improved TPR-tree index structure is built. Then the SQL syntax considers time and event, so it satisfies some question query. And it also discusses how the query language of event oriented fits for snapshot data model query.; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000260989401322&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology; EI; CPCI-S(ISTP); 1
语种	英语
DOI标识	10.1109/IGARSS.2006.730
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/312050]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Huang Zhaoqiang,Chen Xiuwan,Zhang Xianfeng,et al. An Event Oriented Approach for Spatial Temporal Data. 2006-01-01.

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