The Study Of The Integrated Location-based And Object-Oriented Spatio-temporal Data Model And Its Application In Land Use/Land Cover

The information of reality described by GIS is changing over time.Along with the extending of application area of GIS, time dimension as a factor as important as space was added to GIS, and temporal GIS (TGIS) emerged. Since TGIS has the ability of providing auxiliary decision-making,it depicts a nice future to people. Comanying with fast development of the technology of computer,information,method of getting spatial data,TGIS obtains more and more attention.Now,the keys of research of TGIS are spatio-temporal database model(how to design and bulid a valid structure of database to store spatio-temporal data),spatio-temporal analysis and reasoning(how to analyse the data including time reasonsing and space reasoning domain according to the aboundant of time-series data and spatial data stored in database), spatio-temporal database manage system(people focus on the query language of spatio-temporal mostly, and less reseach work was done in database manage system),spatio-temporal visualization(to explore the display methods of time-series data,mapping technique and ways of symbolizing the data),and spatio-temporal data model is the foundation of TGIS here.Now spatio-temporal data models apply in different application area,and much progrss has maken,but still some problems exist,such as lacking of understanding in spatio-temporal semantic,simplification in spatio-temporal connotation,pay more attention to temporal description,neglecting spatial charactors,and being restricted by data sturcture,etc,which effect the ability to deal with spatio-temporal information seriously. The author considers that management of spatial information is as important as temporal information in the course of spatio-temporal modeling, and preserving the charactors of spatial information is the basic competence for spatio-temporal data model.Hence,proper integration of spatial modeling method and temporal information organization can endow spatio-temporal data model more strong vitality.From the view of the evolution condition of spatio-temporal data model, the trend of it, the deficiencies in the models, and based on spatial modeling approach of integration field-based model and object-based model, a Integrated Location-based and Object-Oriented Spatio-temporal Data Model is proposed, and some technical details and arithmetics are also described in this dissertation. The content of this paper is as follows:(1) By analysing the respective charactors of field-based method and object-based method,considering the relationship of space-independent attributes and the spatial charactor of geographical entites, a spatio-temporal data model based on integration of field-based and object-based method is proposed.In the model,’event’ is introduced. Changes based on field(space-independent attributes) are considered as explicit events, which are the’cause’ of change, describing part spatial change of geographical entity. Whole spatial change of the geographical entity which caused by explicit events are called implicit events, which are the’result’ of change,depicting the change based on object that caused by all partial spatial changes occured on the entity.Temporal information in the spatio-temporal data model is denoted by the events arrayed in the time-line according the time when they occur, and the changes are characterized by explicit events and implicit events.The model eliminates the deficiencies of other spatio-temporal data models which apply raster data structure or vector structure.In the model, topological information of object is preserved whenever how it changes, changes of geographical entity are studied, capabilities of description in changes, such as emerge,pullulation and death of geographical entity, are displayed, and the functions of spatio-temporal visualization and query based on field,object and time are provided.(2) Considering change cognition is relative to the ability of dealing with spatio-temporal information for model, based on qualitative method for geographical entity changes by Claramunt,Hornsby and Egenhofer, a method is proposed to express change degree quantitatively by utilizing similarity theory in this disertation. By computing the similarity degree value between objects in different periods, we can judge wether the change is a ’quantitative change’or a’qualitative change’, and in the method, combing the similarity elements computed in the system, spatial change type of an object can be recognised, and the kindred of an object are distinguished if it occurs a qualitative change.The method can choose to bulild a new version for an object or to store it as a new object in database by the change degree of a geographical entity. The change type can be confirmed, which is the foundation of storing spatio-temporal and tracking spatio-temporal process.(3) Considering the intuitionistic charactor of static visualization techniqe when changes are illustrated, based on three ways of temporal visulization,such as wedges,rings and time slices,are proposed by Poonam Shanbhag,a spatio-temporal static visualization expression method based on’annual ring’ is proposed in this disertation.For’ annual ring’,one year per wheel,thickness differ. That the broad ’annual ring’ informs people of have sufficient sunlight and moisture content, and narrow’annual ring’ indicates that year of drought.The’annual ring’ is able to express the condition of growth by its thickness, and the bright line expresses exuberant growing because of much water in spring season, while the cimmerian line expresses the characteristic of slow growth in summer. By referencing these’annual ring’ characteristics, the attributes and spatial characteristics are united in the visualization method proposed in this dissertation. Attributes are transformed into values as thickness of’annual ring’, the spatial characteristic is regarded as the shape of’annual ring’, and the periods that the geographical entity passes are expressed for the amount the circle of’annual ring’, at the same time visual variables are used in the course of visualization.A prototype system about land use application based on the method of integrated Location-based and Object-Oriented Spatio-temporal Data Model is programmed using VB 6.0, and the land use maps of several villages lied in Dongguan city, Guodong province, in 2003,2004 and 2006 are chosen.From the experimental results, the spatio-temporal data model proposed in this disertation is preferable to process the local changes based on location and change process based on object.which eliminates the deficiencies of managing spatio-temporal information and query that caused by limits of data structure used in spatio-temporal data model based on raster or vector.Research on spatio-temporal data model based on raster is comparatively few in TGIS, and the method proposed in this desertation can be a complementarity for it. Experimental analysis also proves that in the method,simple spatio-temporal connotation is avoid, the change course of a geographical entity,such as birth,growth and death, and the relations between temporal aspect and spatial aspect are expressed, and topological charactor is preserved during the change course of geographical entity. Since the data structure integrated vector and raster is adopted in the method, integration of different kinds of spatial data is possible.The integrated Location-based and Object-Oriented Spatio-temporal Data Model proposed in this disertation introuduced a new cognition approach, i.e, field-based spatial model can be regarded as a lower degree model than object-based spatial model,which provides a solution for both discrete spatial changes and continuous changes.