Sumitoshi Ogata

Investigation on turbidity and flow patterns in half-closed sea area

Abstract The sea features on half-closed bays and coastal areas were investigated by satellite remote sensing. The turbidity on the Kanmon area and Hiroshima Bay was estimated by using a new classification technique with the aid of the sea truth data. The performance of this method on a personal computer was examined for comparison with the most likelihood method (MLM) in the course of the investigation. It has been found that this method is more stable against noise and fluctuation of system parameters in addition to the improved computing time than the MLM, and that the classified results are almost same as those of the MLM. This technique was extended and applied to the environmental researches on the coastal areas of the southernmost Korea which face the Sea of Japan and the industrialization has been emphasized there. The data used in the present study are LANDSAT MSS and TM, NOAA AVHRR and MOS-1 MESSR.

Effects on tidal fluctuations by windings of Kuroshio current and flow path monitoring by nonlinear analysis

We analyze hourly-based tidal data acquired at the Izu Islands and the Kii Peninsula to investigate the behaviors of the Kuroshios flow axis because it has a remarkable effect on the tidal fluctuation when its flow axis approaches the southern coasts of Honshu Island. The time-frequency analysis by a wavelet transform and the nonlinear time series analysis are employed to demonstrate the effects of Kuroshio an the tide. The present study aims to reveal the tidal behaviors under the influences of Kuroshio through the visual illustrations of the results by the wavelet transform. In addition, the phase trajectories of the time series also disclose a plausible direction of the Kuroshios flow axis.

Phenomenological approaches to co-oscillating tide in Ariake Bay by time-frequency, nonlinear methods

There is scarce information on Ariake Bay though it is very controversial from a point of view of ecology. The marine harvests in the bay have been highly damaged. The decrease of the productivity of the bay is quite apparent, so we will have to clarify the main negative factors. In the present study, we attempt to disclose the special features of this inner bay by a time frequency approach and a nonlinear method along with the satellite observations for better understandings on the bay and obtaining a clue to prevent more damages. These approaches aim to obtain some findings on this bay, especially a delicate rhythm of tidal movements which may have to do with high productivity of the bay.

Improved spatio-temporal correlation method for velocity field measurements

Abstract We have improved the spatio-temporal correlation method to obtain velocity field from moving images. The new method can specify a certain image frame out of many sequential frames of a moving object and determines its 2-D velocity field on the basis of the specified frame. In addition, it enables us to avoid an edge effect of velocity field that appears at both ends of image sequence. This improvement has enhanced reliability and reduced computational time, compared to the previous methods. As a further application, we will describe this method’s application to a non-solid moving object and a sport scene analysis.

Control of chaos by system noise and observation noise

The effects of noise on chaotic behaviors of nonlinear model systems are described from a point of view of the disorder and order of the systems. We used two types of noise, i.e., the system noise and observation noise. The effects of the noise intensity on the chaos were observed through the changes of the attractors, correlation dimension and maximum Lyapunov exponent.

Time series image analysis of Dalian, China by remote sensing

We have long observed the changes of the Dalian areas using remotely sensed image time series from the point of view of human activities. We employ Landsat TM and ETM+ data to evaluate quantitatively the rate of progress due to its modernization in connection with weather and geographical conditions since such a research is still in an early stage of its development. The analysis by unsupervised classification techniques indicates a steady increase of land area and a steady decrease of vegetation in the Dalian areas irrespective of the difference of the methods. These facts show that the present approach gives us a measure of human activities.

Quality estimation of lime stones for print paper coating materials by image instrumentation

The present study aims to obtain a measure to evaluate the quality of raw limestone. As a macroscopic approach, we employ a remotely sensed satellite image with high spatial resolution which provides a birds-eye view of the limestone mine and spectral properties of the naked limestone rocks surface. The second approach uses a commercial digital camera and we attempt to grade the sample limestone samples materials of different quality for screening the limestone powders used as coating materials for printing papers. The statistical quantities on the sample images and their fractal dimensions are applied for the evaluation of the quality.

A New Classification Algorithm for Satellite Remote Sensing Image Data based on a Personal Computer and Its Application to Water Area Environment Study.

多重分光リモートセンシング画像データを高速に, かつ, 少ないメモリー数で分類処理するための新しい手法を開発した.本方法では数十ないし数百の画素を一まとめにしてセルとし, セルを基準として分類を行っている.二つのセルのヒストグラムの類似性を比較することで, 全てのセルは一度に簡単に分類される.本方法の妥当性と実用性を検証する目的で, 本方法を関門水域および豊後水道の水質汚濁調査に適用した.関門を境として, 周防灘の濁度は響灘の濁度よりも高いことが確かめられた.また豊後水道の観測から, 水質汚濁と混同され易い小波の強い影響を本方法によって明らかにした.