Urban Geo-spatial Information Updating Technology

The present situation is a life of basic geographic information. Only when basic geographic information has to renew continuously can it reflect truly the present situation of the nature and cultural features. On the base of deep studying, this paper provides the practical solution of the urban geo-spatial information updating quickly facing the rapid development of our country city building. The present situation is a life of basic geographic information. Only when basic geographic information has to renew continuously can it reflect truly the present situation of the nature and cultural features. As everyone knows, urbanism is the inevitable result of social development. For the sake of well coming true the strategy target of making country strong with science-education and sustainable development, our country has put forward several significant strategic steps, such as "Small town, Great strategy" and the "Migrating to set up city" etc. Therefore, the step of our country’s urbanism will speed up further. All of these bring forward the direct and urgent need of the urban geo-spatial information's acquiring and updating quickly. Geographic information is the basic part of national information source. The high-speed development of social economy greatly enhance the real need of geographic information, meanwhile, it accelerates the change of all kinds of geographic information. Now, geographic information industry confronts with new chances and challenges. At present, geographic information industry is trying all effort to achieve the goal of digitalization, automation and intellectualization. This tendency reflects clearly in the integrating of remote sensing technique (RS), global positioning system (GPS) and geographic information system (GIS) in geographic information industry’s technology system. While the best approach for acquiring and updating of urban geo-spatial information is to accomplish the integration of 3S techniques in the geographic information. 1. THE TECHNOLOGY OF URBAN SPATIAL INFORMATION ACQUIRING AND UPDATING QUICKLY 1.1 The Technology of Urban Change Detection Automatically Although the time when to update spatial information can be determined on experiences, it is hard to be prompt. Updating period depends mainly on the change degree of geographic information according to the principle. Therefore, it is full possible to detect the change degree automatically from satellite remote sensing imagery. In this way, not only updating geo-spatial data can be prompt, but also that when and where needs to be updated can be ascertained reasonably before time. Once the time and place that need to be updated is determined, it is necessary to make plans for acquiring image. Usually, the renewed areas are not large, and the different renewal areas are dispersed. To update the spatial data, there’s only one way to achieve “prompt”, which is the mechanism of spatial data updating based on orthophotos. As far as geo-spatial data updating, there is only one approach to achieve “prompt”, that is the mechanism of spatial information updating on the basis of orthophoto maps. The exterior elements of updated images can be solved directly according to the original orthophotos. In this way, it neither needs control points, nor aerial triangulation; therefore, the work efficiency can be improved greatly. And then, the data are collected on the basis of image registration. Considering that most cities of our country haven’t build orthophoto images database, however, the necessary method of updating data must include the situation without orthophoto database. 1.2 The Technology of Acquiring Information The technology of ground observation with high resolution is one of the key technologies to realize city’s changing spatial information. With the rapid development of geomatics, the technology of ground observation will be multi-phasic, multi-angled, and has high resolution. America is speeding up its plan to launch business satellites with the resolution of one meter, which means houses and cars in the city can be seen clearly in the image. And it is important for city’s changing information with large scale and high resolution. In the technology of obtaining information with ground observation, use CCD sensor to replace traditional film so that system can obtain digital image directly in the course of flying, which makes it possible to realize the real-time transmission of observe data. At the same time, CCD sensor enhances system’s ground observation ability, shortens the period of processing information, and improves the currency of ground observation. At present, there are two different CCD sensors. One is based on areal array sensor, and the other is based on linear array sensor. Compared with CCD areal array chip, the technology of linear array chip has faster development, and CCD-line sensor has successful application in aerial sensor of our country. However, if we want apply CCD-line sensor in aerial platform, it needs the technology of gyro-stabilized platform with high accuracy to match, so this kind of technology is limited. Surface