The Key Technology Of Massive Multi-scale Geospatial PDF Basic Geographic Data Management

With the rapid development of electronic computer science technology and GIS(Geographic Information System)technology,electronic map is gradually applied to people's various areas such as learning and living.However,the majority of basic surveying and mapping data is still limited to professional GIS software and expert users due to the large size of map data,wide area coverage,multi scales and complex format.How to apply and popularize the basic geographic data better in the daily life of people,and to satisfy the demand of mass multi-scale basic surveying and mapping products storing,organization,management and transmission distribution at the same time is the difficulties faced by the basic geographic data producers and managers.Portable Document Format is one of the most commonly used free document format.It has a lot of advantages,such as it contains abundant information,transmits data through network safely and quickly and it is easy to use.Based on these characteristics,Geospatial PDF(GPDF),which is extended from standard PDF through georeferencing,provides a new way to solve the problems mentioned above.This paper analyzes the feasibility of GPDF expressing basic geographical mapping and surveying data,on this basis studies the key technologies of massive multi-scale GPDF basic geographic data storage,management,and provides a new train of thought for the management of basic geographic data.This paper mainly finishes the following works:1.Based on the detailed analysis of PDF document structure,aiming at the geographic coordinates and positioning,logical layers,the vector geometry/attribute data,raster data,and text notes of basic geographic data,this paper studies its extension methods in the GPDF document organization.It selects Esri ArcGIS and TerraGo Publisher software to compare and analyze the result of the different basic geographic data transferring to GPDF map,and then verify the availability of GPDF maps.2.Due to the demand for massive multi-scale GPDF data management and visualization,it studies the tile pyramid model and quad tree index technology,and puts forward a GPDF manage method,which is based on tile pyramid and quad tree index technology.3.The paper studies the process of cutting GPDF into block geographical tiles hierarchically,designs the GPDF data naming and storing method,and provides the basic thought to access real-time GPDF files,splice and browse the tiles seamlessly.4.Based on Adobe Acrobat SDK and Adobe PDF Library SDK,this paper designs and develops an Acrobat plugin for GPDF.By using some sample data as experiments,it verifies the characteristics of responding fast,dragging the map smoothly and access the data real-time,which satisfies the need of browsing massive multi-scale basic geographic data seamlessly.