Geospatial Information Technology

ABSTRACT This paper studies the methods of large-scale CAD-based data acquiring, data transforming between CAD data and GIS data e date updating in database. A file format called SIF (Spatia l Information format) is designed for transforming data format, which is represented by XML. Based on the arithme tic for addition acquiring and addition updating, a large-scale data transferring and updating system is developed with ArcEngine fund on the project of Hi-tech Zone Infrastructure GIS (HiGIS) in ChangZhou, and there are 308 blocks of 1:2000 maps in ChangZhou have been done experiment on transferring and updating, which realizes th e spatial data sharing between CAD and GIS. Keywords: Data parsing, Versioning, Data updating 1. INTRODUCTION 1.1 Version management for spatial data The mode of spatial data management has undergone file management and relational database combining file management to relational database manD gement. Today object-oriented relative database become the mainstream of spatial database because of expre ssing object-oriented concepts. Version is the tool that offers long transactions management by ArcGIS based on multi-users operation. It can notes and manages the state of database in the processes of altering and evolving. Every version of spatial database represents an exclusive view of seamless database or an exclusive logical snapshot .A version can be distinguished with others by a series of editing assemblage, which notes the features edition such as addition, modification and deletion. The original data are stored by Base Tables and the modification is stored in Additions Table and Deletions Table. Versioning management not only reduces the quantity of data, but also shows variance of terrain, features and urbanized advancement. 1.2 The actuality of spatial data in china Spatial data plays a decisive role in the applications of GI S, and expense for acquiring data and building database takes 2/3 of all the expense in GIS. The spatial data currency is th e bottleneck of the applications for GIS. It is important and difficult to assure the currency of spatial data, which is reflected in the following aspects: