Landsat-5 TM データを用いた松江・出雲地域の土地被覆分類

Land cover type is mapped in the Matsue and Izumo areas using Landsat-5 Thematic Mapper（TM）data from 1985 to 2000 to study the long-term change in land cover in this region. For the classification, land cover is divided into 6 classes, i.e. urban area, forest, rice fi eld, vegetable fi eld, water, and “others”. The digital number（DN）output of the Landsat-5 TM is used to make a maximum likelihood estimation of the class for each location. A land utilization map produced from an in-situ survey in this area is used for ground truth to obtain the probability density function of the 6 classes and to evaluate the classification accuracy. After an examination of band combination signifi cant for the classifi cation, either 6 bands or 5 bands（the same as the 6 bands but excluding the green band), ranging from 0.45 to 2.35 μm, are used for the classifi cation. The accuracy of the classifi cation is evaluated against the ground truth data in the Matsue City area. The accuracy is higher than 60％ for urban, forest, rice fi eld and water ; the accuracy for vegetable fi eld and “others” falls below 60％ . The best accuracy（higher than 90％）is obtained for the water area classification. Complicated spectral refl ectance characteristics and complex spatial distribution of the vegetable fi eld and “others” classes may be the cause of the degraded accuracy. From the long-term land cover change analysis a signifi cant increase of urban area is clearly detected.