Research On Web Crawler-Based Geographic Information Acquisition Technology

With the rapid development of computer network and geographic information technologies, geographic information data has become a kind of important basic of geographic information resources. it has not only been widely used in state construction of city planning, traffic navigation, disaster monitoring, national military defense and other fields, and is becoming more and more closely associated with People's Daily lives.Especially Google provides people with public service based on space position, has brought great convenience to people's work and life.Geographic information data in promoting national economic and social development,brings very much convenience to people's work and life, at the same time, there are also some problems to be solved. Among them, the prominent problem is geographic information acquisition issue, Traditional approaches of geographic information data acquisition by methods of field surveying and remote sensing. These methods have such problems of high cost, low precision, and cannot be updated in real time etc. At the same time, network geographic space has the characteristics of virtual, sharing, without borders, especially in the network now dotted with many geographic information data, all of this has proposed a new way and source for geographic information acquisition, researches on how to obtain geographic information data from the network is of great significance.This paper mainly studied the key technologies on acquisition of geographic information data from network. Respectively according to different types of geographic information data such as text, and the grid put forward different ways to obtain. For text geographic information data acquisition, mainly through Web Crawler technique to obtain, this paper studied the variety of Web Crawler algorithm, this paper will be based on the content of Shark Search algorithm and HITS algorithm based on link, put forward a new algorithm of web crawler, namely SS - HITS algorithm, this algorithm can not only reduce the local problems and theme drift phenomenon in the algorithms, but also improved the web crawler page callback rate and precision. For raster geographic information data acquisition technology,this paper mainly through the analysis of its key technologies, such as projection methods,data organization and management model, this paper proposes a grid geographic information acquisition scheme, through the scheme can obtain the global high precision raster geographic information data; In addition, this paper puts forward a kind of map matching, roaming and scaling algorithm, this algorithm can not only acquire the raster geographic information data to joining together into a complete image maps, but also support the function of map roaming and map zoom for the maps.