著者

高橋 徹 臼井 敏夫 藤島 豊久 大木 真人 佐野 博昭 小定 弘和

出版者

The Remote Sensing Society of Japan

雑誌

日本リモートセンシング学会誌 (ISSN:02897911)

巻号頁・発行日

vol.36, no.4, pp.360-366, 2016-09-20 (Released:2017-03-24)

参考文献数

10

被引用文献数

2

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The L-band synthetic aperture radar (SAR) satellite, ALOS-2 (Daichi-2), has a capability for educational purposes. The radar aboard ALOS-2, named PALSAR-2, has a wavelength of 24 cm, compatible with a makeable reflector size for children. In addition, as the spatial resolution of the radar is approximately 3 m, children can easily draw a letter in the radar image by deploying their own reflectors in the schoolyard. We have developed a sufficiently reflective corner reflector (CR) that can be easily built by children. In experiments, we clarified that ALOS-2 can detect reflected waves from a CR with a side length of three times the radar wavelength. We also developed free software that enables children and their educators to analyze most earth observation satellite data including ALOS-2 PALSAR-2 data. In 2014, we established an educational program called “Let's expose ourselves on Daichi-2 data” with the YAC-J (Young Astronauts Club Japan) and EORC (Earth Observation Research Center), JAXA. We have also held seminars for educators in various places in Japan. As a result, more than 20 groups have implemented the program. We conclude that this program enables children and their educators to feel a connection to space and fosters their interest in their native environments.

著者

大木 真人 夏秋 嶺 青山 定敬 田殿 武雄

出版者

一般社団法人 日本リモートセンシング学会

雑誌

日本リモートセンシング学会誌 (ISSN:02897911)

巻号頁・発行日

pp.2021.075, (Released:2022-04-16)

参考文献数

27

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Increasing human and economic losses due to urban floods demand rapid flood monitoring using synthetic aperture radar (SAR). In a global first, this study conducted simultaneous experiments using a flood experimental field that can reproduce the conditions of submerged buildings and satellite monitoring using the L-band SAR aboard the Advanced Land Observing Satellite-2 (ALOS-2). Through these experiments, we investigated the relationships among the threshold of interferometric coherence, the accuracy of urban flood detection, the multi-look number in interferometric processing, and floodwater depth. To achieve a better understanding of our experimental results, we also performed theoretical coherence simulations. Our results revealed that the coherence and flood detection accuracy statistically depends on the multi-look number and that 3×3 looks are needed to obtain reasonable accuracy. We also found that coherence-based change detection can detect urban floods with a depth of as little as 6 cm. There was no clear correlation between coherence and water depth. We also performed urban flood detection using ALOS-2 data from observed flood events; the results proved the validity of our theory and its applicability to actual disaster activities. Our findings enable robust urban flood monitoring and contribute to disaster prevention and mitigation.SAR, PALSAR-2, disaster monitoring, flooding, interferometry

著者

夏秋 嶺 渡邉 学 大木 真人 本岡 毅 鈴木 新一 島田 政信

出版者

社団法人 日本リモートセンシング学会

雑誌

日本リモートセンシング学会誌 (ISSN:02897911)

巻号頁・発行日

vol.37, no.1, pp.1-12, 2017-01-31 (Released:2017-08-23)

参考文献数

20

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In this paper, we evaluate the potential accuracy for the volcanic ash coverage using interferometric coherence of the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite-2 (ALOS-2, “DAICHI-2”). In order to detect the disaster affected area from interferometric coherence, we require pre-disaster and co-disaster pairs. That is, we require at least two interferometric archives taken before the disaster in addition to one archive after the disaster. The ideal multi-temporal analysis is performed with of course, highest resolution pairs. However, we do not always have enough number of the archive especially in the early stage of the satellite mission. Here, we use not only Stripmap but also ScanSAR mode archive in order to achieve enough number of pairs. The combination of the Stripmap and ScanSAR archives will help to increase the interferometric pair while it suffers the spatial resolution and coherency. Especially for ALOS-2 PALSAR-2 data, it has not been evaluated the potential accuracy of such Stripmap-ScanSAR interferometry method. In this paper, we use the volcanic eruption event in May 2015 at Kuchinoerabu-jima Island, Kagoshima prefecture, Japan for the case study. We evaluated the proposed method with the truth data which was achieved by manual classification using aerial photography. Experimental results showed that the proposed method marked approximately 91% overall accuracy with 0.64 Kappa coefficients to detect the dense volcanic ash coverage.