In application of geographical information system, it is important to extract artificial objects on the ground automatically from aerial images. We aim at road which has parts of connection between areas. But analysis of aerial images needs much time to process because the images are very large. In this paper, we present a method to reduce the time to analysis by dividing images. The size of image to be divided depends on edge density. If a region has high edge density in image, the region is divided into smaller size. Also we present a method using color feature on the assumption that road has similar color. Using these methods, we propose road extraction method using divided K-Means algorithm, in which we use color (CIE L*u*v*) and location (x, y) information. Using the result of road extraction, road map is described according to a logical model of road. We show the result of road extraction. Finally, we evaluate the computational cost and the quality of the result of road extraction.
An approach to use satellite data for quantitative estimation of the fixation of nitrogen by different vegetation types over river basin ecosystems was proposed and applied to a mountainous area located in the upper reach of Nagara river basin (Gifu Prefecture, Japan) covered predominantly with multiple vegetation types. In addition to satellite data, this approach also involved the use of census data, statistics data and previous results available in literature as supporting materials. With this approach, the annual amounts of nitrogen absorbed by different categories of forest vegetation classified in terms of species and ages using the satellite data were estimated. Validation tests were performed by comparing the satellite data-based estimations (Ndsatellite) with estimations from a budget model (Ndmodel) and statistics data (Ndrecord), respectively. It was found that the estimated NdsatelliteN (100.8-111.7kg ha-1y-1 for broadleaved forest, 35.4-71.4kg ha-1y-1 for evergreen coniferous forest, 91.4kg ha-1y-1 for mixed forest) coincided well with the values of Ndmodel (96.0-100.4kg ha-1y-1 for broadleaved forest, 48.0-74.0kg ha-1y-1 for evergreen coniferous forest, 82.3kg ha-1y-1 for mixed forest) and were somewhat larger than those of Ndrecord although the values of Ndsatellite and Ndrecord were all in the same order of magnitude for respective vegetation types classified.
Terra MODIS is one of the few space-borne sensors currently capable of acquiring radiometric data over the range of view angles. Institute of Industrial Science (ITS), University of Tokyo, has been receiving Terra MODIS data at the Komaba Campus station and at Asian Institute of Technology (AIT), Bangkok on direct broadcasting system since May 2001. The coverage includes whole East and South Asia and is expected to monitor environmental changes regularly such as deforestation, forest fires, floods and typhoon. Over eight hundred scenes have been archived in the storage system and they occupy 2 TB of disk space so far. In this study, MODIS data processing system on WWW is developed including following functions : spectral subset (250m, 500m and 1000m resolutions), radiometric correction to radiance, spatial subset of geo-referenced data as a rectangular area with latitude-longitude grid system in HDF format and generation of a quick look file in JPEG format. Users will be notified via e-mail just after all the processes have finished. Using this system enables us to process MODIS data on WWW with a few input parameters and download the processed data by FTP access. An easy to use interface is expected to promote the use of MODIS data. This system has been available via the Internet on the following URL since September 1 2002, “http: //webmodis.iis.u-tokyo.ac.jp/”.
The Geographical Survey Institute (GSI) constructed the new geodetic datum of Japan, “Japanese Geodetic Datum 2000 (JGD2000) ”. The coordinates of the old geodetic datum of Japan, “Tokyo Datum (TD) ”, should be replaced by JGD2000. This report proposes precise and minimum bias transformation for the public and cadastral survey networks. Least squares collocation method is used for the precise transformation. To minimize a network bias, the transformation parameters are calculated over a small area every year. The transformation keeps the network configuration constant.“TKY2JGD”software is published by GSI to transform the coordinates from TD to JGD2000. This report also proposes that transformation distortion of the TKY2JGD can be estimated by applying the strain theory. The distortion of transformed coordinates is expressed by angle and scale changes. The angle and scale changes correspond to the maximum shear strain and dilatation respectively.
A new explanation on Carrier Phase DGPS being used in GPS survey is given in this paper. In order to easily understand the essentials of the technique, Carrier Phase DGPS in two-dimensional space is firstly described concretely, and then actual case (three-dimensional space) is introduced briefly. The explanation is begun with an ideal case such as achievement of synchronization among receivers, and then real conditions are added. It is also proven that the new explanation is very effective for undrestanding on new applications of GPS, including RTK-GPS and VRS.