Masaaki Shikada

Extraction of Landslide Areas Using Spatial Features of Topographic Basins

Spatial features of watersheds are examined to clarify characteristic properties in areas where landslides may occur. In this study, first, a method for delineating watersheds from the digital terrain data is described. Next, the area (A), mean slope (S) and form factor (F=A/L2) of watersheds are estimated. Here, L is the length of the main stream in a watershed. As a result, it is shown that topographic features in landslide areas are successfully characterized by a linear combination of the normalized values of A, S and F.

Extraction of characteristic properties in landslide areas using thematic map data and surface temperature

It is well known that in the Noto area in Hokuriku district of Japan, landslides occur in all seasons. Most small-scale landslides, which the authors have investigated, occur near streams in valleys with a gentle slope. Moreover, it is said that underground-water supplied by rainfall and snowfall strongly relates to these landslides. The objective of this study is to find areas where landslides may occur in the near future by using infrared band data and visible band data obtained from a Landsat TM sensor with Thematic-Mapper data related to landslide areas. As a result, at many landslide segments in investigated areas, the authors found that the surface temperature in landslide areas is higher than in non-landslide areas.<<ETX>>

Effects of solar and view angles on reflectance for paddy field canopies

Abstract It is very important to know the spectral characteristics for the sake of understanding the remote sensing data. The reflectance characteristics of paddy field canopies vary with time or observational conditions (solar zenith angle, solar azimuth angle, and view zenith angle). A number of field studies have clarified the effects of these conditions on grain canopy reflectance. Most of the field data used in these study, however, were conducted only through the growing season in one year or by grains planted in pots. A series of authors’ experiments were initiated in 1982 and continued from the spring to the autumn every year to 1987. In this study we describe that the remotely sensed spectral data measured on the ground are influenced not only by the grain type, observational conditions, and growing season but also by the solar zenith angle, solar azimuth angle and view zenith angle in relation to scene. In this paper we report the results from the investigation of these various fundamental prope...

REAL TIME GIS by collaboration of remote sensing, GPS and GIS

Much local government has been using large scale digital maps with Geographic Information System (GIS). However, the updating method of a map is not established yet, and there are very few successful examples. The purpose of this study is the real-time renewal of the digital map for local government by using Remote Sensing and Real-time Kinematic Global Positioning System (RTK-GPS). First, change of the city is easily found by overlay Remote Sensing imageries and digital map with GIS. Next, Position of changed area was measured by RTK-GPS. REAL TIME GIS is the system for real-time mapping and updating at the field site using RTK-GPS, GIS and cellular phone. But, RTK-GPS measuring data did not correspond with digital maps because of different geodetic system. It is necessary to transform digital maps of an old geodetic system to new ones. In order to solve this problem, the parameters were calculated using Affine Transformation. In this paper, these parameters were named “High-Accuracy Regional Parameter (HARP)”. As a result, it was differences less than 3cm in any case. In conclusion, the need of HARP with Affine Transformation was indicated. It is suggested that the process of REAL TIME GIS and HARP should be introduced to the work of local government.

Extraction of topographic features in landslide areas from ERS-1 SAR data

An analysis has been undertaken of characteristic features of the ERS-1 SAR image in areas where landslides may occur. First, statistical quantities of SAR data corresponding to landslide areas and non-landslide areas are computed for the study site (the Noto peninsula in Japan). As a result, it is shown that the difference of mean values of gray levels between landslide areas and non-landslide areas is of no significance. Moreover, the drainage system is extracted on the basis of the assumption that some streams will be defined by the dark strips caused by the combined effects of shadow and open water. It is found that the extracted drainage courses correspond to the dark strips that are visible on the SAR image as valleys.<<ETX>>

Universal map for spatial information society by using REAL TIME GIS, GPS and remote sensing

Government has to hurry up to build accessible facilities for elderly people and people who has disabilities. Because our country is experiencing an aging society, for example, pedestrian space should be safe and give a relief. One of the methods to ensure this society is to obtain absolute position with high accuracy. Therefore, we suggested here to make Universal Map (UM) with a large scale (1/500 or 1/1000) by using REAL TIME GIS. The purpose of the research was to confirm whether absolute positions can be obtained accurately in pedestrian space. The experiment was performed by moving in KIT campus by a wheelchair to which D-GPS and VRS-GPS antennas have been attached. As a result, it became clear that any experiment fields could not receive accurate data. To solve these problems, we adopted IC tags which are new ubiquitous technology. For a solution, it is recommended that the UM be made by the REAL TIME GIS and IC tags.

The utility of renewal system for barrier-free map by using remote sensing and RTK-GPS

Research proposed that wheelchair user uses remote sensing (RS), Real-Time Kinematic-Global Positioning System (RTK-GPS) and Geographic Information System (GIS) support to make barrier-free map. In this paper, Remote Sensing means high-resolution satellite imageries. If equipment of RTK-GPS attach to wheelchair, barrier-free map can be able to revise as the imageries on computer every day. Wheelchair users always can get the latest information of urban conditions. Proposed system automatically make barrier-free map. In other words, it suggests that mapping process dose not need much labor and time. In addition, the system as mentioned above makes more useful barrier-free map using Remote Sensing imageries as a background. Combination of remote sensing, RTK-GPS and GIS applied to barrier-free map prepared by local government improve rapidly life style for wheelchair users

Extraction of landslide areas using satellite remote sensing and GIS technology

The objective of this study is to find areas where landslides may occur in the near future by using satellite remote sensing and thematic-map data, also using GIS (Geographic Information System) techniques. The authors considered how the combination of GIS with remote sensing data and thematic map data may facilitate greatly the assessment and estimation of regional landslide hazards. They extracted inclination angles, inclination aspects, and ridge and valley lines from DTM data originally made for landslide areas. The watersheds in the study areas were extracted by GIS techniques. Criteria to predict landslide areas are proposed.

Inference of landslide areas using spatial features and surface temperature of watersheds

An inference of landslide areas using digital elevation data and Landsat TM band 6 data has been performed on the basis of the assumption that the occurrence of landslides is closely related to the amount of underground-water and the topographic features of watersheds. It is shown that it is possible to distinguish between dangerous landslide areas and non-landslide areas by using spatial features of watersheds, such as the area, mean slop and shape factor, and the ground surface temperature obtained from Landsat TM data.

Map renewal technique by using collaboration of GPS, GIS and remote sensing

Much local government has been utilizing the large scale digital map with Geographic Information System (GIS). GIS will be able to efficiently work and to reduce mapping costs. However, the maintenance and renewal of a map database need much labors and time. However, the updating method of a map is not established yet and, there is little successful example. The purpose of this study is establishment to update of the large scale map for local government by using a REAL TIME GIS and its collaboration. REAL TIME GIS, which definition decided by our laboratory, is a technology that updates the digital map instantly by using RTK-GPS and the cellular phone. RTK-GPS data use Japanese Geodetic Datum 2000 (JGD2000) of WGS-84, but most of the digital map of local government is still Tokyo Datum of old geodetic system. In order to correspond with two kinds of data which have different geodetic system, it is necessary to transform coordinates. Geographic Survey Institute of Japan (GSI) opened a website for the conversion parameters and programs. GPS data is able to apply to digital map in small scale. However, Base Map and thematic map which has made by the large scale (1/500 or 1/1000) on the old geodetic system did not obtain sufficient accuracy. To solve these problems, our laboratory proposed High-Accuracy Regional Parameter (HARP) which changes from an old geodetic system to a new geodetic system.