Based On The Study And Application Of The The Web2.0 Network Geographic Information System (webgis)

Since the first Geographic Information System(GIS) was born in the world in 60's,it spring up and develop rapidly as a newly arisen edge academics,which integrate computer science,geography,mapping and remote sensing science, environment science,city science,space science,information science and management science now,the geography information system is forming complete technique system and gradually building up its independent theoretical system.It has been applied in many realms of the society,aside from the traditional natural resources management,land programming etc.but expanding to the transportation, military,business...etc.,and obtained a huge economic benefit.Because of the strong need for society geography information system(GIS),the application of GIS become extensive day by day.beside,the Computer science rapidly developing also provided GIS with advanced tools and means making the GIS develop quickly.When we get into 21 century,Internet technique popularize fast,which further make GIS transform fundamentally,the Internet had become the new operation terrace of GIS.the combination of Internet and GIS,namely WebGIS,changed the methods of obtaining,delivering,releasing,sharing and applying of geography information.Make use of Internet to release and publish geography information on the Web and provide for the customer the functions of browsing spatial data, inquiring about and fabricating special subject map and analyzing to carry out operation and share of geography information,which have already become the inevitable development trend of GIS.The rise of WEB2.0 techniques provided a better technique support for the realization of WebGIS.WEB2.0,differing from the HTML page of traditional Web applied program and static data delivering mode,bring a new kind of data delivering mode,characterized of highly interaction,which can satisfy the customer's higher and all-directions need for experience,and possess of network applied procedure enriching customer experience.First,This text introduced WEB2.0 techniques in detail and development history and characteristics of geography information system(GIS),and then discuss the method for realization of WebGIS.finally,This text detail how to carry out WebGIS with Ajax,contained in WEB2.0.Main work,technique crux and innovation that this text treat of are as follows: 1.This text elaborated the rise and development of Web2.0 techniques,and discussed its characteristics and the main technique used,combined with its various applied fields in current and comparison with the traditional WEB technique.2.Geography information system(GIS),supported by computer hardware and software,is a technique system which collects,store,manage,operate,analyze, shows and describes all kinds of spatial data and its properties/attributes in real world(resources and environment).This text introduces the origins,makeup,main functions and development history of GIS,and discussed spatial data structure of the GIS at length.3.WebGIS is a network geography information system,based on Internet,permitting, saving,handling,analyzing,displaying and applying geography information.This text discussed its strongpoint,development trend and difference from the traditional GIS.Meanwhile we studied the method of realization of WebGIS detailedly.4.when researching several traditional methods which carry out WebGIS,we suggest that we can realize WebGIS with Ajax within the conditions of development of network technique,the system realized like that is essentially different from the one which is developed by ArcIMS,MapXtreme etc.secondhand in interior mechanism.This text introduced the process of realization in detail,the creative place are as follows:a.The processing of spatial data.The map in this system is not created dynamically according to the user' s request,but is created by the way that grid pictures are produced in advance,and then transformed into image pyramid,named in the way that is similar to four fork trees coding after sliced into pieces,finally deposited in a server.Thus the burden of system is reduced when producing picture dynamically.b.Cut the map into slices and do,load asynchronously at the customers'. When the window of the map move and zoom,the system need to download pictures to fill new area,making best use of the function that is the multi-threading download at one time of browser(such as IE) s asynchronous communication mechanism of Ajax.Only new pictures need to be downloaded. There is no need accessing server again to download the pictures which have been downloaded.In the traditional way,the system obtain all data over again to produce photos and then transport them to users or download all data to users for producing photos. c.Map operating may be interrupted,or map operations can not be done when there is no result for attribute searching,or attribute operations is impossible when map operations are not finished in the traditional WebGIS. But this text turns all these disadvantages away by using Ajax.d.In realization in first layer in this text,a great deal of XML,VML,CSS, javaScript script etc.technique is brought to bear.The WebGIS system that this text carries out acquires good practical result and evaluation from customers.