The Exemplary Effect of GeoStar in the Spatial Data Infrastructure Construction in China
Keywords: spatial data infrastructure; digital geospatial data framework ; digital orthophotos; DEM; integrated spatial database.
Abstract
This paper presents some ideas about the design and implementation of the China National Spatial Data Infrastructure, base on a pilot project . The production technologies and processes to collect spatial data are described, and An integrated spatial database management system based on Geostar is also introduced.
1. Introduction
As the rapid development of computer and information technologies, geographic information system (GIS) has come into practice. At present, geographic information system construction and its application have sprung up. In the application of the geographic information system, an urgent problem to be solved is data sharing. After years of developing, we have gained certain geospatial data and thematic data and thematic data. The National Bureau of Surveying and Mapping has possessed of spatial data with scales of 1:2,500,000, and 1;10,000,000 covering the whole China and has produced spatial data with scales of 1;100,000 and 1:500,000 in some regions. Many big cities have accomplished the work of digitalization of large -scale map. However, the major problem to be settled of the current GIS development is how to manage and maintain the spatial data, which will lead to the spatial data sharing.
Spatial Data Infrastructure (SDI) is an important concept proposed for the sake of spatial data sharing and distribution. In the recent years, organizations related to the UN, national, provincial and local governments of each country have attached much importance to the SDI at all levels. Global Spatial Data Infrastructure ( GSDI), Regional Spatial Data Infrastructure (RSDI), National Spatial Data Infrastructure (NSDI), Provincial Spatial Data Infrastructure (PSDI) and Urban Spatial data Infrastructure (USDI) have come forth, which has promoted SDI and NII constructions to an important strategic status of the future informations society development. The main propose is to establish relevant organizations and criteria , expedite the production of spatial data, reduce repetitive collection of spatial data, maintain the reality, validity and authority of spatial data and accelerate the development of GIS .
SDI includes four aspects : first, the system of organizations and data distribution, second, the spatial data criteria, third, spatial data clearinghouse which includes large-scale severs, high speed communication networks, spatial database managing system, spatial data distribution and so on, fourth, digital geospatial data framework. In SDI, one apparent feature of digital geospatial data framework is that it includes not only traditional vector data, but also digital orthophotos data and Digital Elevation Model (DEM).
GeoStar is a GIS software developed by Geo information engineering Company at Wuhan Technical university of Surveying and Mapping. The Software covers all the functions of current GIS software. So as to adapt to the special need of the National Spatial Data infrastructure, it also includes many special function.
Aiming at the situation the most current commercial GIS software is difficult to meet the need of SDI construction, when Wuhan Technical University of Surveying and Mapping was developing GeoStar , the National Bureau of Surveying and Mapping had proved that GeoStar would carry out the pilot project study of PSDI. In the following, the implementary technologies of the pilot project of PSDI construction will be introduced in detail.
2. The contents of the spatial data set
In order to establish the spatial data infrastructure in China as soon as possible, factors such as the speed and efficiency required to collect spatial data and the completion, importance, processing and expansion of the information have to be considered. Therefore, the spatial data set should be a Digital Geospatial Data Framework (DGDF), which includes the following contents.
First, the most important type of geospatial data the digital orthophotomap. Digital photogrammetry or remote sensing will be adopted in the production of the digital orthophotomap at the scales 1:10,000 and 1:50,000. the production technologies to produce the digital orthophotos have already come into operation rapidly and efficiently . in addition, the digital orthophotos have already come into operation rapidly and efficiently. In addition, the digital orthophotos includes such abundant information the vector data can be captured from the orthophotos according to user's needs.
The Digital Elevation Model (DEM) is not only used for generation of the digital orthophotos, but also serves many application in GIS such as road design, flood prevention and agricultural planning. The form of Dem can be grid, TIN or hybrid.
Several layers of vector data are necessary. These vector data should include administrative boundaries, transportation and drainage. These three layers of vector have many GIS application, and they are included because they are both important and easy to collect.
The cadaster, extent of residential area, vegetation, pipe lines and communication lines are also normally useful in GIS. But collecting these vector data would take a long time, and therefore these data are not includes in the DGDF of China.
A DGDF must also include a geodetic control point database ad a place name database. These tow kinds of data are stored in a table and their positions displayed on the digital map.
In total, the Digital Geospatial Data Framework of China should include digital orthophotos, digital elevation models, administration boundaries, transportation and drainage as well as the database of geodetic control points and database of place names. Other features can added properly when users need them. If only the geographic information above is produced, the working efficiency can be 5 to 10 times faster than by vectorizing full- feature maps. It can meet the demand of rapid renewal of a national GIS caused by the rapid development of the economy in China.
