• Title/Summary/Keyword: RADARSAT SAR 영상

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Study on the extraction of ocean wind, wave and current using SAR (SAR를 이용한 해풍, 파랑, 해류 추출 기법 연구)

  • Kang, Moon-Kyung;Park, Yong-Wook;Lee, Moon-Jin;Lee, Hoon-Yol
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.1
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    • pp.187-194
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    • 2006
  • Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave, and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette, The Doppler shift measurement of SAR image yields surface speed of the ocean current along the rador looking direction, again at imagette resolution. In this paper we report the development of a SAR Ocean processor (SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images of the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of spaceborne SAR-based oceanographic research.

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Study on the Extraction of Ocean Wind, Wave and Current using SAR (SAR를 이용한 해풍, 파랑, 해류 추출 기법 연구)

  • Kang, Moon-Kyung;Park, Yong-Wook;Lee, Moon-Jin;Lee, Hoon-Yol
    • Journal of Navigation and Port Research
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    • v.31 no.1 s.117
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    • pp.35-42
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    • 2007
  • Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave, and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette, The Doppler shift measurement of SAR image yields surface speed of the ocean current along the radar looking direction, again at imagette resolution. In this paper we report the development of a SAR Ocean processor(SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images of the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of spaceborne SAR-based oceanographic research.

Extraction of SAR Imagery Informations for the Classification Accuracy Enhancement - Using SPOT XS and RADARSAT SAR Imagery (광학영상의 토지피복분류 정확도 향상을 위한 SAR 영상 정보의 처리에 관한 연구)

  • Seo, Byoung-Jun;Park, Min-Ho;Kim, Yong-Il
    • Journal of Korean Society for Geospatial Information Science
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    • v.8 no.1 s.15
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    • pp.121-130
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    • 2000
  • For the land-cover classification we have usually used imagery of the optical sensors only. But currently a number of the satellite with various sensors are operating and the availability of using the data acquired from them are increasing. SAR sensors, in particular, can produce additional informations on the land-cover which has not been available from optical sensors. On this study, I have applied the SAR Image to the SPOT XS image in the classification procedures, and analysed the classified results. In this procedure I have extracted texture informations from SAR intensity images, then applied both intensity and texture informations. From the accuracy analysis, overall accuracy are increased slightly when the SAR texture was applied. In case of the Built-up class the results showed higher accuracy than those of when only the SPOT XS image was used. From this result I can show that overall accuracy was increased slightly but the spatial distribution of classes was visibly improved.

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Feature Extraction and Classification of Multi-temporal SAR Data Using 3D Wavelet Transform (3차원 웨이블렛 변환을 이용한 다중시기 SAR 영상의 특징 추출 및 분류)

  • Yoo, Hee Young;Park, No-Wook;Hong, Sukyoung;Lee, Kyungdo;Kim, Yihyun
    • Korean Journal of Remote Sensing
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    • v.29 no.5
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    • pp.569-579
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    • 2013
  • In this study, land-cover classification was implemented using features extracted from multi-temporal SAR data through 3D wavelet transform and the applicability of the 3D wavelet transform as a feature extraction approach was evaluated. The feature extraction stage based on 3D wavelet transform was first carried out before the classification and the extracted features were used as input for land-cover classification. For a comparison purpose, original image data without the feature extraction stage and Principal Component Analysis (PCA) based features were also classified. Multi-temporal Radarsat-1 data acquired at Dangjin, Korea was used for this experiment and five land-cover classes including paddy fields, dry fields, forest, water, and built up areas were considered for classification. According to the discrimination capability analysis, the characteristics of dry field and forest were similar, so it was very difficult to distinguish these two classes. When using wavelet-based features, classification accuracy was generally improved except built-up class. Especially the improvement of accuracy for dry field and forest classes was achieved. This improvement may be attributed to the wavelet transform procedure decomposing multi-temporal data not only temporally but also spatially. This experiment result shows that 3D wavelet transform would be an effective tool for feature extraction from multi-temporal data although this procedure should be tested to other sensors or other areas through extensive experiments.

Subsidence Observation of time-series surface deformation at New Orleans using Differential SAR Interferometry (레이더 차분간섭기법을 이용한 뉴올리언스 지역의 시간에 따른 지표변위 관측)

  • Jo, Min-Jeong;Lee, Chang-Wook;Park, Jeong-Won;Won, Joong-Sun
    • Proceedings of the KSRS Conference
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    • 2008.03a
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    • pp.148-152
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    • 2008
  • 뉴올리언스는 미시시피 강 하구에 위치하였으며 지난 2005년 허리케인 카트리나에 의해 큰 침수 피해를 입은 지역이다. 이 도시는 신생대 지층에 자리하고 있어 미고결층의 다짐작용 및 단층작용으로 최대 29mm 정도의 연간 침하율을 보여 왔다. 뉴올리언스의 계속된 침하작용은 평균해수면보다 낮은 지역에 위치한 도시의 침수위험성을 가중시키고 있어 현재 이에 관한 많은 연구가 진행되고 있다. SAR영상을 이용한 차분간섭기법(DInSAR, Differential Interferometry of SAR)은 지반침하, 지진, 화산활동 등과 같이 수십 km$^2$에 걸쳐 발생하는 지표변위를 수cm-수mm의 정밀도로 관측 가능한 기술이다. 이 연구에서는 차분간섭기법을 이용하여 2005년 2월부터 2007년 2월까지 촬영된 21개의 RADARSAT-1 Fine beam mode(F5) 영상으로부터 25개의 차분간섭영상(DInSAR Interferogram)을 생성하였다. 또한 차분간섭도의 spatial decorrelation을 극복하고 시간에 따른 LOS 방향의 변위를 관측하기 위해 분석 알고리즘으로는 보완된 SBAS(small baseline subset)기법을 이용하였으며, 이 기법을 이용하여 대기의 영향 및 노이즈를 제거한 결과를 얻을 수 있었다. 우리는 LOS방향의 2차원 변위분포 맵을 작성하였으며, 그 결과 전체적인 침하율은 크지 않지만, 도시의 서쪽지점에서 나타나는 상대적으로 큰 -1.49cm/yr의 변위 값과 동쪽 지점에서 0.33cm/yr의 변위 값을 관측하였다. 이 같은 결과는 앞으로의 연구에서 실측 데이터 및 동일기간의 다른 SAR영상자료의 연구를 통해 보완해 나갈 것이다.

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Interannual Changes of Bar Morphology in the Han River Estuary Using Satellite Imagery (인공위성에 의한 한강 하구역 퇴적상 경년 변동 특성 조사)

  • Yang, Chan-Su
    • Proceedings of KOSOMES biannual meeting
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    • 2007.11a
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    • pp.57-60
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    • 2007
  • The Han River is divided into North and South Korea by NLL(Northern Limit Line) and its area has been blocked by CCL(Civil Control Line) since the Korean War in 1950. Satellite remote sensing, therefore, is uniquely suited to monitoring bar transformation in the region. In river with bar, the characteristics of its physical conditions have a close relationship with bar morphology. In this paper, a monitoring approach of bar transformation in the Han River Estuary is presented using RADARSAT/SAR images from 2000 to 2005 and spatial patterns of bar morphology are presented. It could be said that in the estuary vegetated area and natural levees are developed well, but bars are shifted after an event like a flood. It is also showed that suspended solids such as silt transported through the estuary could contribute highly to a sedimentation environment around Incheon.

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Analysis of Relationships between Features Extracted from SAR Data and Land-cover Classes (SAR 자료에서 추출한 특징들과 토지 피복 항목 사이의 연관성 분석)

  • Park, No-Wook;Chi, Kwang-Hoon;Lee, Hoon-Yol
    • Korean Journal of Remote Sensing
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    • v.23 no.4
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    • pp.257-272
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    • 2007
  • This paper analyzed relationships between various features from SAR data with multiple acquisition dates and mode (frequency, polarization and incidence angles), and land-cover classes. Two typical types of features were extracted by considering acquisition conditions of currently available SAR data. First, coherence, temporal variability and principal component transform-based features were extracted from multi-temporal and single mode SAR data. C-band ERS-1/2, ENVISAT ASAR and Radarsat-1, and L-band JERS-1 SAR data were used for those features and different characteristics of different SAR sensor data were discussed in terms of land-cover discrimination capability. Overall, tandem coherence showed the best discrimination capability among various features. Long-term coherence from C-band SAR data provided a useful information on the discrimination of urban areas from other classes. Paddy fields showed the highest temporal variability values in all SAR sensor data. Features from principal component transform contained particular information relevant to specific land-cover class. As features for multiple mode SAR data acquired at similar dates, polarization ratio and multi-channel variability were also considered. VH/VV polarization ratio was a useful feature for the discrimination of forest and dry fields in which the distributions of coherence and temporal variability were significantly overlapped. It would be expected that the case study results could be useful information on improvement of classification accuracy in land-cover classification with SAR data, provided that the main findings of this paper would be confirmed by extensive case studies based on multi-temporal SAR data with various modes and ground-based SAR experiments.

Tracking of Internal Waves Observed by SAR in the Time Series of Temperature Profile Data (시계열 등온선 자료에서의 SAR로 관측된 내부파의 추적 연구)

  • Kim, Tae-Rim
    • Korean Journal of Remote Sensing
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    • v.25 no.2
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    • pp.155-163
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    • 2009
  • An abundance of internal waves is observed by SAR in the Yellow Sea during summer. They are small scaled internal waves and are not relatively studied well compared to the ones in the East/South China Sea. These internal waves should be considered in the study of physio-biological properties of the Yellow Sea because the mixing of the stratified surface water caused by internal waves during summer is important for ocean biological environment, and they also affect the sediment transport and acoustic signal transmission in the continental shelf region. To understand the characteristics of internal waves, it is important to get the spatio-temporal information of internal waves simultaneously by executing in-situ measurements as well as the SAR observation. This study tracks the internal waves observed by SAR in the time series of temperature profile data by analyzing simultaneously acquired in-situ measurement data and RADARSAT SAR image on 29 May 2002.

An Example of Internal Wave Detection in North Coastal Waters of Cheju Island Using a SAR Image (SAR를 이용한 제주도 북부해역에서의 내부파 관측예)

  • Kim, Tae-Rim;Won, Joong-Sun
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.4 no.1
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    • pp.18-24
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    • 1999
  • The satellite image acquired by RADARSAT SAR on August 15, 1996 reveals internal waves in north coastal waters of Cheju Island. It is indicated from the image data, the tidal elevation data, and the bottom topography data, the internal waves seem to be generated by interaction between shallow bottom and tidal currents travelling in the stratified water in the summer time during the tidal changeovers from ebb to flood. The internal waves generated in such condition show patterns of trains of solitons. Probable amplitude of observed solitons is calculated using estimation of the soliton wave length from SAR image data and K-dV equation. Detection of the internal waves is very significant not only to military strategist for underwater maneuvers such as operation of submarines, but also to physical and biological oceanographers. Temporal and spatial variation of the internal waves are needed to be measured by simultaneous in-situ field study together with SAR to examine the nature of these internal waves.

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A study on the estimation of damage by storm and flood using satellite imagery (풍수해 피해규모 파악을 위한 위성영상의 활용방안 연구)

  • Sohn, Hong-Gyoo;Yun, Kong-Hyun;Lee, Jung-Bin;Jin, Kyung-Hyuk
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2007.04a
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    • pp.111-114
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    • 2007
  • One of future remote sensing techniques for the estimation of damage by storm and flood is the extraction of water area, which could be the basis of measuring the damage by storm and flood and estimate restoration cost. This paper introduces an approach to damage estimation using satellite Image. The project site was Ansung area and a set of Radarsat-1 SAR image at 6.25m resolution was used for the test. Authors investigated methods of SAR image processing such as shadow-effect removal, orthorectification of SAR image and calculation of damage area by flood. Consequetly, this study showed that technique improvement of image processing and the best of result for extracting water area. Also, found the new possibility of damage estimation using satellite image.

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