The aim of this study is to make a quantitative analysis with respect to landslide occurrence behavior by using GIS. First, simplified ortho correction technique for SPOT images without orbit data is newly developed in this study. Next, brightness correction is carried out to the SPOT images. Finally, tests for algorithms of the automatic detection of landslides were iterated till the best-fit is derived. Comparing with the result from aerial-photo interpretations in the training area, the hit ratio in number of landslides are about 73% in Tanzawa region and 52% in Boso region, respectively. However, error detection mostly occurs at small landslides, and the landslides with over 2000m² are detected correctly.
The relation between the cumulative number of landslides and the landslide area follows power function, therefore the behavior of landslide occurrence might relate to the model of self-organized critical phenomenon. On the basis of this assumption, it may be inferred that landslide occurrence is complicated interaction of elements. Thus, the prediction of individual landslide occurrences and its magnitude might be impossible by seeking a few parameters. When those relations are examined in detail, we can see the bending point that can divide all data into two segments. Then, the value of threshold is statistically obtained by calculating Akaike Information Criterion (AIC): 7500m² in Tanzawa and 5100m² in Boso. Because the bends are observed in both regions, it can be inferred that there is a different mechanism for landslide occurrence between large landslides and small landslides.

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This paper aims to clarify the effects of the building shadow on the albedo in urban areas using remotely-sensed data. The albedo distribution was estimated from a set of remotely-sensed data of resolution 18m. The shadow of buildings was then obtained from land use data in a vector format. Analysis of the relationship between the building shadow ratio and the satellite derived albe-do in a central area of Tokyo showed a negative correlation between them. The negative correlation found in the high-rise building area of Nishi-Shinjuku was the most significant. These results suggest that the albedo value of a certain location in urban areas which is estimated from satellite data is strongly affected by the building shadow in its neighboring area.

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This paper shows a procedure for evaluating the differences between two spatial tessellations which are made by different mapmakers, and unifying these tessellations into one tessellation. First, we show a pre-processing method. Second, we show a method for detecting topological differences and adjusting these differences. Third, we define the 'skeleton' of a boundary to make two corresponding boundaries into a uniform coarseness and develop a method for analyzing whether or not skeletons of these boundaries are qualitatively similar. For qualitaitively similar boundaries, we develop a method for measuring quantitative differences in terms of parallel motion, rotation and expansion. Last, we propose a method for unifying two boundaries into one boundary.

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In this paper we discuss performances of various interpolation methods used to generate a precise digital elevation model (DEM). Generally, the interpolation methods are classified into the following three types: type 1 generates a DEM from contour lines; type 2 does from knots of latticed meshes, and type 3 does from sparse points. Here, we examined type1 and type 2. The methods of type 1 that we examined are Akima's interpolation, cubic spline interpolation, cubic surface interpolation, morphological interpolation and Inaba's interpolation. Also, the methods of type 2 we did are linear interpolation, Akima's interpolation, cubic spline interpolation, bicubic spline interpolation and FFT interpolation. Using artificial and real topographic data, we evaluated these methods systematically and made their performances of interpolation accuracy clear. We concluded that morphological interpolation and Akima's interpolation method are relatively effective in type 1, and that cubic spline interpolation and Akima's interpolation method are effective in type 2.

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Viewshed analysis based on digital elevation model is one of the most common operation in GIS. The viewshed or visible area is naturally defined using a sightline between a observation point and a target point, but its calculation is computationally intensive. In this paper, formal definitions on visibility are provided by using sightplane as well as sightline, and their equivalence is proved. To form the sightplane as a covering plane, three points including the observation point are selected. As these point can be selected in distance base order, redundant check of invisibility becomes evitable. On this basis, an efficient and simple algorithm is proposed and demonstrated for its superiority to the sightline algorithm.

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In the past research, authors have prepared the map of a preserve area of grassland from the point of landscape evaluation mainly. However, grassland has been managed and maintained by the grassland association of stockbreeding farmers in Aso region for a long time. It is also important to investigate the possibility of existence of the association for preserving grass landscape. In this paper authors propose the method to extract a preserve area in terms of multi-standard evaluation using AHP, and illustrate an integrate map of preserve area along the main roads in this area by using GIS.

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According to popularization of geographic information system (GIS), temporal data management becomes very important. When GIS is used in daily work, the most frequently accessed data is the present data. So, the access speed on the present data should not be lowered in spatiotemporal data management. Furthermore, the past data should also be able to be restored. This paper proposes a spatio-temporal data management method based on a geographic differential script file (GDSF) method. This method records the change of map in the form of graphical operation with the time print. When an old data becomes necessary, the data is restored by applying the GDSF onto the current map data. For executing spatial retrieval fast, this paper describes a combination method of spatial data structure GBD tree and the GDSF.

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Recently many kinds of spatio-temporal data are repeatedly acquired or generated mainly because of the recent rapid progress of data acquisition technology. However those data are still so limited and "fragmentary" in terms of observation frequency, spatial coverage and thematic accuracy etc. that we can not always monitor dynamic changes of spatial objects or features with sufficient spatial-temporal resolution directly from those data. In order to reconstruct the dynamic changes of spatial objects or features with sufficient spatio-temporal resolution, we have to "integrate" a variety of fragmentary data. In addition, it is very desirable to revise the reconstructed dynamic changes of spatial objects whenever new observation data are added to the spatio-temporal database (We call it "dynamic updating"). For this purpose, it is necessary to improve a framework of GIS in order to represent observational data and dynamic changes of spatial objects under external disturbances, in addition to the development of integration methodologies. In this study we propose FEO (Feature/ Event/Observation) model as a conceptual framework of spatio-temporal database which enables dynamic updating.

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The objective of this paper is to propose new methods for analyzing relationships between point objects distributed on a network.
First, the K function method, which is used to analyze a distribution of point objects on a continuous plane, is extended into the network K function method to be applied to a distribution on a network. Second, the network cross K function method is defined as a method that deals with the relationship between two distributions of point objects on a network. Third, a computational method for the network K function methods is proposed.

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This paper is the first part of a series of papers that proposes a method to estimate precision of spatial information. This deals with an error model of points on spatial information. The model is based on two-dimensional normal distribution. A probability density function of distances between two points is formulated. Then expectation and variance of it is calculated. Finally, case studies are done and precision of the first class triangulation net of Japan is estimated as about 1.41 meter in standard deviation.

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This is the second part of a series of papers that proposes a method to estimate precision of spatial information. This paper deals with the method how to estimate precision by distances of 2 points in real and on spatial information. First of all, the model proposed in part 1 is modified. Then a method to estimate standard deviation based on the maximum likelihood method is introduced. Finally, computational simulation is done.

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This is the third part of a series of papers that proposes a method to estimate precision of spatial information. This paper deals with the method how to estimate precision by overlaying some kinds of spatial information. First, the model presented in part 1 and 2 is modified. Then a method to estimate standard deviation by overlaying some kinds of spatial information is introduced. Finally the model is applied to a case in which position error generated by map overlay is examined.

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We developed a new method for evaluating forest diversity of forest compartment. Two multi -temporal Landsat TM data were used and the clustering was applied to these data for forest classification. Number of derived clusters and pixels in each forest compartment were counted, and the forest diversity index was calculated from these values by using Simpson's formula. It was found that this method gives reasonable evaluation results, for example, the forest diversity index showed relatively high score at the forest compartment which consist of both conifer and broad leaf forest.

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The purpose of this study is to improve methods estimating for the distribution of population along urban roadways with heavy traffic in order to account the population exposed to serious noise or air pollutant. Recently, a census covering the whole country provides the population data with the Basic Unit Blocks and the locations data of its center point. Population density in the range of every 10 meters from the roadway is estimated by allocating the population data into the polygon data of blocks on the market. For more detail, the number of population could be allocated into polygon of buildings according to floor space and floor uses. The linear approximation of census population data could be applied for estimating the spatial distribution of people, if the polygon data are not available for the targeting area.

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Geographic Information System (GIS) is playing an increasingly significant role for management and conservation of wildlife species on a worldwide scale. However, only a few examples and active researches of the GIS-based wildlife studies have been reported in Japan. Although wildlife management and species diversity conservations have been emerging as a controversial issue, geo-scientific spatial efforts have been hampered by the lack of cohesive sets of data in Japan. We present our concept for the development of a GIS-based wildlife management system and research. This paper briefly explains a use of grid-polygon as an effective data acquisition and ana-lytical tool in the GIS-based wildlife management in Japan.

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Nowadays in Vietnam, although still adopting the policy that land itself is not individual property, land-use rights, such as exchange, transfer, rent, inheritance or mortgage, are considered as property in reality. This means that a trading market of land-use rights is emerging and becom-ing increasingly popular. In order to manage and develop this market, it is necessary for Vietnam to have a land appraisal system based on market economy principles. On the other hand, the develop-ment of a GIS and its applications to property appraisal can help the property appraisal to be more convenient and accurate. Recently, a Vietnamese National Geographical Information System is in the first step of development and the GIS will be applied in many other fields such as the environ-ment, cadastres, etc. This paper proposes a land valuation system for Vietnam after considering other countries' property valuation systems, especially the Korean Official Announced Land Price, and applies GIS techniques for the system. Especially by network analysis, distances from the main roads are computed in the real distances travelled along the roads rather than calculated perpendi-cular distances.

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