Vol.1 No.2 2008

6/85

Research paper : Creation of seamless geological map of Japan at the scale of 1:200,000 and its distribution through the web (K. Wakita et al.)−75 Synthesiology - English edition Vol.1 No.2 (2008) though they may be acquainted with recent researches. They often become confused by unfamiliar explanations and expressions in old maps. In order to remove this obstacle, we developed a method for seam-smoothing geological maps, and applied it to the 1:200,000 geological maps, because they almost completely covered the Japanese Archipelago, whereas the 1:50,000 maps were insufficient for the purpose.2.2 Goals and scenariosNothing can make geological maps more valuable than their wide spread use in the society. We set our research goal as follows: to contribute to the safety of our society by integrating the geological maps that were created independently and by promoting the use of these maps through effective delivery.The research scenario to achieve the above goal is as follows (Figure 2):・Revision of each map drawn according to different geological models, recompilation with the latest integrated standards, and seam-smoothing with adjacent maps・Delivery of harmonized maps on the Internet, rather than by print or CD-ROM media, to facilitate wide use in the society・Standardization of the expression of geological information to allow interoperation with other ground information inside and outside Japan3 Procedures for harmonizing geological maps3.1 OutlineHarmonization of geological maps involves revision of old geological maps based on past models by applying up-to-date models. The procedure includes unification of legends and adjustment of geological features such as boundaries and fault lines (Figure 3). In order to give priority to prompt distribution of the results, no extra field surveys were conducted in this project.The 1:200,000 geological maps, of which 112 maps have already been published, cover about 90 percent of Japan (as of March 2006), and they are most detailed maps that could be harmonized. The revised seamless geological maps of Japan based on these maps are the most frequently used example of seamless geological map[8].Launched in 2002, the project published areal seamless maps in series as follows. In 2003, Hokkaido and Tohoku regions were completed, followed by the Kanto region in 2004, completing the eastern half of Japan. Three regions of Hokuriku, Tokai, and Kinki were completed sequentially in the same fiscal year. In 2005, Chugoku and Shikoku regions, Kyushu region, and Nansei Islands were completed, covering the western half of Japan. Adding several areas of southern Kanto region (Izu Northern Ogasawara, Izu Southern Ogasawara) and eastern area of Hokkaido (including four islands of the Kuril), as well as the revision of Hokkaido region, the first edition of the national seamless map was published. This digital geological map was drawn with unified legend and consisted of massive amount of data involving 149,081 polygons and 371,528 lines (as of May 12, 2007)[9].3.2 Unified legendThe first step in seam-smoothing geological maps was unification of the legend. As legend gives all description of geological features in the map, it was necessary to develop a common legend applicable to all neighboring maps under the latest geological model. However, limited amount of information in old geological maps makes it impossible to apply the latest legend to all maps. Most up-to-date yet most widely applicable legend was chosen based on recent geological model.The unification was carried out in two stages, applying the existing legend system and applying it to the 1:200,000 maps. Fig. 2 Elemental technology and scenario for Japan Seamless Geological Map Project.Printed MapSurveyType I Basic ResearchLatest Geological ModelUnified LegendDigitizationApplication of GISGeological divisionUnified legendHarmonizationof unit boundaryOriginal MapsSeamless Geological MapType II Basic ResearchSeamlessGeologic Map WiderUsage ofGeologic Maps PurposeIntegrated TechnologyUnified Geologic LegendHarmonized boundaryWeb distributionInteroperable dataElementsNewest Geologic ModelGIS ApplicationDigitizationCoverage of geologic mapsImage Display TechnologyLegend ArrangementGeospatial StandardsGeoinformationStandardsStructurizing InformationGeological FieldworkFig. 3 Concept and process of Seamless Geological Map of Japan 1:200,000.(3)−

※このページを正しく表示するにはFlashPlayer9以上が必要です