1. T. Yaku et al. intoduced octgrids that are graph expressions of multi-resolution three-dimensional topographical maps, intermediate code (H7CODE) that is a grid graph, and a list structures. figure 2 is an example of rectangle division and the corresponding octgrids Geographical Concept Recognition with the Octgrid Method for Learning Geology and Geography Ryusuke Yokoyama*, Akira Kureha*, Tomoe Motohashi**, Hiroyasu Ogasawara*, Takeo Yaku*, and Daisuke Yoshino* Nihon University*, Kanto Gakuin University** yaku@cs.chs.nihon-u.ac.jp, {ryusuke, kureha, yoshino}@yaku.cs.chs.nihon-u.ac.jp cspeirce@chs.nihon-u.ac.jp, tomoe@kanto-gakuin.ac.jp Introduction To provide learners with skills for recognizing geographical concepts. Reviw octgrid method. Our system runs on 3D maps in octgrid data format. Propose an automatic recognition system for ridges, valleys, and contour lines. Application of the above systems to an integrated CAI system, ggCAI. Figure 1. rectangular dissection D1 and octgrids G1 that correspond to D1. Figure 2. Contour lines near Mt. Fuji. Moving from the outside inward, the black lines represent the altitudes of 1000 ， 1500 ， 2000 ， 2500 ， 3000 ， and 3500 meters. Extraction of ridges and valleys operates to down dissection of the maximum called drive line. When we extract a valley we reverse →the numerical values Geographical Concept Recognition Module Characteristic topography extraction in this article means that which displays general geographical ideas a mountain, ridge, valley, contour line, or delta based on data of meters above sea level. Application to Learning System of Geology and Geography This section deals with the specifications and structure of courseware Each set of contents has a link from each corresponding list of geography, or earth science topics. The number of contents: Eight places (contour line, valley, and ridge per one place) We incorporate the output of a geographical concept recognition system in CAI. Figure 7 is an example of applying a CAI system. Figure 3. Ridge extraction of Mt. Fuji.Figure 4. Valley extraction of Mt. Fuji. Yana river Yumifuri river Yachiba river Figure 5. Example of expressing a drainage basin. A drainage basin is the whole area of a region where water from rain and snow flows into a river. Figure 6. Snapshot of courseware. Conclusion We have developed a system that provides a large number of required examples in classrooms. Future Work:A recognition system of delta and alluvial fan. We also provide a system for recognizing ridges, valleys, and contours from landform maps. Future Work: A Geographical concept recognition system corresponding to a world topographical map. We have applied the two systems to a CAI system for the study of geology and geography. Future Work: To incorporate a geographical concept recognition system in CAI. IEEE Internat. Conf. Adv. Learning Tech. (ICALT2007), July 2007, Niigata, Japan Input: DEM file and a number to show a place. Output: Geographical Concept Recognition file. The number of the steps: 352. Description language: C. Input: DEM file and a number to show a place. Output: drainage basin file. The number of the steps: 387. Description language: C. Input: DEM file and a number to show a place. Output: Contour line file. The number of the steps: 137. Description language: C. Background: Octgrid Method