Development of the Seamless Digital Geological Map of Japan: Application of Google Maps API

Geological map series of Japan in scale of 200,000 was completed on March, 2010 by Geological Survey of Japan (GSJ), National Institute of Advanced Industrial Science and Technology (AIST). These traditional paper-based geological maps had different regional legends because of differences of produced time and composer, and those caused structural and stratigraphic discordance between adjacent geological maps. The Seamless Digital Geological Map of Japan (http://riodb02.ibase.aist.go.jp/db084/index_e.html) is produced by (1) creating nationally-standardized legend based on the geological map of Japan 1:1,000,000, 3rd edition (GSJ,1992), (2) digitizing existing paper-based geological maps in vector format, (3) replacing each geological attributes by the nationally-standardized legend, (4) smoothing geological boundary of adjacent maps on Geographic Information System (GIS). GSJ has published the maps on the Web since 2003, and providing data to users. Methods of data representation have been modified to suit the needs of the users. Google maps version is the latest user interface which uses Google Map API (Application Programming Interface) and Google Earth API provided by Google. Google Maps version generates image tiles of geological map by using GIS for each zoom levels, and displays the map by overlaying tile layers. This method requires no vector calculation, and only transfers data within display range in a manner similar to original Google Maps. To sum up the major characteristics of the Google Maps version, easy-to-follow operability similar to Google Maps and shorter response time than other systems that use Web-GIS are the most significance. KMZ files for Google Earth are downloadable from the website.