• 제목/요약/키워드: SAR Data

검색결과 618건 처리시간 0.033초

고해상도 SAR 영상의 활용기술 동향분석 (Investigation of Applications Technology for High Resolution SAR Images)

  • 윤근원;고진우;이용웅
    • 한국군사과학기술학회지
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    • 제13권1호
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    • pp.105-113
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    • 2010
  • SAR(Synthetic Aperture Radar) has characteristics well-suited for the measurement of geophysical parameters during day and night in all weather conditions. Recently, SAR data with high resolution acquired by satellites became available to the public. In such data, many features and phenomena of geometric structure of man-made objects and natural environments become observable. In this paper, we discuss main considerations including geometric distortion and coregistration for efficient utilization of high resolution SAR images. And, various advanced technologies in SAR application fields are introduced.

Ad Hoc 네트워크 라우팅 보안을 위한 다중경로 기반의 MP-SAR 프로토콜 (Multiple Path Security-Aware Routing Protocol Mechanism for Ad Hoc Network)

  • 한인성;유황빈
    • 한국통신학회논문지
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    • 제33권5B호
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    • pp.260-267
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    • 2008
  • 기존의 SAR(Security Aware Routing)[9] 프로토콜은 Ad Hoc 네트워크의 보안경로를 발견하는 프로토콜로, 이동 노드에 부여된 보안레벨 속성 값을 라우팅 정보로 이용하는 보안라우팅 프로토콜이다. 그러나 SAR 프로토콜은 암호화된 데이터 전달을 위해 보안노드를 경유로 데이터를 전송하므로 비밀통신과 효율적인 통신이 고려되지 않고 있다. 또한, AODV[3] 프로토콜 기반으로 동작하기 때문에 데이터의 전송 중 중간노드의 배터리소진 또는 중간노드의 이동으로 데이터 전달에 있어 통신이 단절될 경우 보안노드를 경유하는 라우팅 경로를 재탐색하게 되어 데이터의 전송지연 문제가 발생한다. 그 외에도 SAR 프로토콜의 특성상 재탐색의 경우 노드간의 연결은 가능하지만 데이터 전송에 있어서 요구되는 노드의 보안레벨 이하의 노드인 경우 경로설정이 중단되는 문제들로 재연결이 용이하지 않다. 본 논문에서는 SAR 프로토콜의 문제점을 개선하기 위해 다중경로 기반의 SAR 프로토콜인 MP-SAR을 제안한다. MP-SAR은 데이터의 기밀성을 유지하기 위해 SAR의 보안경로 탐지기법의 확장으로 다중경로를 탐색하고, 유효한 최단보안경로의 이용으로 안전한 고속의 데이터 전달을 할 수 있다.

Estimation of Polarization Ratio for Sea Surface Wind Retrieval from SIR-C SAR Data

  • Kim, Tae-Sung;Park, Kyung-Ae
    • 대한원격탐사학회지
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    • 제27권6호
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    • pp.729-741
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    • 2011
  • Wind speeds have long been estimated from C-band VV-polarized SAR data by using the CMOD algorithms such as CMOD4, CMOD5, and CMOD_IFR2. Some SAR data with HH-polarization without any observations in VV-polarization mode should be converted to VV-polarized value in order to use the previous algorithms based on VV-polarized observation. To satisfy the necessity of polarization ratio (PR) for the conversion, we retrieved the conversion parameter from full-polarized SIR-C SAR image off the east coast of Korea. The polarization ratio for SIR-C SAR data was estimated to 0.47. To assess the accuracy of the polarization ratio coefficient, pseudo VV-polarized normalized radar cross section (NRCS) values were calculated and compared with the original VV-polarized ones. As a result, the estimated psudo values showed a good agreement with the original VV-polarized data with an root mean square error by 0.99 dB. We applied the psudo NRCS to the estimation of wind speeds based on the CMOD wind models. Comparison of the retrieved wind field with the ECMWF and NCEP/NCAR reanalysis wind data showed relatively small rms errors of 1.88 and 1.91 m/s, respectively. SIR-C HH-polarized SAR wind retrievals met the requirement of the scatterometer winds in overall. However, the polarization ratio coefficient revealed dependence on NRCS value, wind speed, and incident angle.

SAR 디스플레이 영상을 위한 무손실 압축 (LOSSLESS DATA COMPRESSION ON SAR DISPLAY IMAGES)

  • Lee, Tae-hee;Song, Woo-jin;Do, Dae-won;Kwon, Jun-chan;Yoon, Byung-woo
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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    • pp.117-120
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    • 2001
  • Synthetic aperture radar (SAR) is a promising active remote sensing technique to obtain large terrain information of the earth in all-weather conditions. SAR is useful in many applications, including terrain mapping and geographic information system (GIS), which use SAR display images. Usually, these applications need the enormous data storage because they deal with wide terrain images with high resolution. So, compression technique is a useful approach to deal with SAR display images with limited storage. Because there is some indispensable data loss through the conversion of a complex SAR image to a display image, some applications, which need high-resolution images, cannot tolerate more data loss during compression. Therefore, lossless compression is appropriate to these applications. In this paper, we propose a novel lossless compression technique for a SAR display image using one-step predictor and block arithmetic coding.

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Oceanic Variables extracted from Along-Track Interferometric SAR Data

  • Kim, Duk-Jin;Moon, Wooil-M.
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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    • pp.429-434
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    • 2002
  • The Synthetic Aperture Radar (SAR) data are considered to contain the greatest amount of information among various microwave techniques developed for measuring ocean variables from aircraft or satellites. They have the potential of measuring wavelength, wave direction and wave height of the ocean waves. But, it is difficult to retrieve significant ocean wave heights and surface current from conventional SAR data, since the imaging mechanism of ocean waves by a SAR is determined by the three basic modulation processes arise through the tilt modulation, hydrodynamic modulation and velocity bunching which are poorly known functions. Along-Track Interferometric (ATI) SAR systems can directly detect the Doppler shift associated with each pixel of a SAR image and have been used to estimate wave fields and surface currents. However, the Doppler shift is not simply proportional to the component of the mean surface current. It includes also contributions associated with the phase velocity of the Brags waves and orbital motions of all ocean waves that are longer than Brags waves. In this paper, we have developed a new method for extracting the surface current vector using multiple-frequency (L- & C-band) ATI SAR data, and have generated surface wave height information.

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The high accurate monitoring technique of land deformation by using satellite image - PSInSAR -

  • Mizuno Toshimi;Kuzuoka Shigeki
    • 한국지구물리탐사학회:학술대회논문집
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    • 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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    • pp.305-312
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    • 2003
  • Remote sensing can provide invisible information in addition to acquire wide-view image data from space. Synthetic Aperture Radar (SAR) transmits microwave to the earth from a satellite and collects the reflected echo from the surface. Interferometric processing of SAR data can detect the subtle land deformation. The information of the surface movement by SAR is useful to monitor the volcanic activity, extended subsidence of urbanized area and the prediction of the earthquake caused by crustal deformation, and it complements the conventional levelling and GPS technique. PSInSAR (Permanent Scatterers Interferometric SAR) is one of interferometric techniques to be applied to practical projects in Japan. In this paper, the projects of land deformation monitoring are shown after the explanations of the PSInSAR principle. Tokai earthquake risk assessment is the first example. PSInSAR detects the subduction of crustal deformation of the adjacent area of new assumed epicenter region of the Tokai Earthquake. The extended subsidence of the urbanized area was implemented by using Japanese satellite data i.e. JERS that has so much data the surrounding of Japan as the archive. We examine the relationship between the geological structure and settlement at Nohbi basin including Nagoya city.

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Investigation of Polarimetric SAR Remote Sensing for Landslide Detection Using PALSAR-2 Quad-pol Data

  • Cho, KeunHoo;Park, Sang-Eun;Cho, Jae-Hyoung;Moon, Hyoi;Han, Seung-hoon
    • 대한원격탐사학회지
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    • 제34권4호
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    • pp.591-600
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    • 2018
  • Recent SAR systems provide fully polarimetric SAR data, which is known to be useful in a variety of applications such as disaster monitoring, target recognition, and land cover classification. The objective of this study is to evaluate the performance of polarization SAR data for landslide detection. The detectability of different SAR parameters was investigated based on the supervised classification approach. The classifier used in this study is the Adaptive Boosting algorithms. A fully polarimetric L-band PALSAR-2 data was used to examine landslides caused by the 2016 Kumamoto earthquake in Kyushu, Japan. Experimental results show that fully polarimetric features from the target decomposition technique can provide improved detectability of landslide site with significant reduction of false alarms as compared with the single polarimetric observables.

Evaluation of the Pi-SAR Data for Land Cover Discrimination

  • Amarsaikhan, D.;Sato, M.
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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    • pp.1087-1089
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    • 2003
  • The aim of this study is to evaluate the Pi-SAR data for land cover discrimination using a standard method. For this purpose, the original polarization and Pauli components of the Pi-SAR X-band and L-band data are used and the results are compared. As a method for the land cover discrimination, the traditional method of statistical maximum likelihood decision rule is selected. To increase the accuracy of the classification result, different spatial thresholds based on local knowledge are determined and used for the actual classification process. Moreover, to reduce the speckle noise and increase the spatial homogeneity of different classes of objects, a speckle suppression filter is applied to the original Pi-SAR data before applying the classification decision rule. Overall, the research indicated that the original Pi-SAR polarization components can be successfully used for separation of different land cover types without taking taking special polarization transformations.

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저수지 저수량 추정을 위한 위성 SAR 자료의 활용성 (Applicability of Satellite SAR Imagery for Estimating Reservoir Storage)

  • 장민원;이현정;김이현;홍석영
    • 한국농공학회논문집
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    • 제53권6호
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    • pp.7-16
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    • 2011
  • This study discussed the applicability of satellite SAR (Synthetic Aperture Radar) imagery with regard to reservoir monitoring, and tried the extraction of reservoir storage from multi-temporal C-band RADARSAT-1 SAR backscattering images of Yedang and Goongpyeong agricultural reservoirs, acquired from May to October 2005. SAR technology has been advanced as a complementary and alternative approach to optical remote sensing and in-situ measurement. Water bodies in SAR imagery represent low brightness induced by low backscattering, and reservoir storage can be derived from the backscatter contrast with the level-area-volume relationship of each reservoir. The threshold segmentation over the routine preprocessing of SAR images such as speckle reduction and low-pass filtering concluded a significant correlation between the SAR-derived reservoir storage and the observation record in spite of the considerable disagreement. The result showed up critical limitations for adopting SAR data to reservoir monitoring as follows: the inappropriate specifications of SAR data, the unreliable rating curve of reservoir, the lack of climatic information such as wind and precipitation, the interruption of inside and neighboring land cover, and so on. Furthermore, better accuracy of SAR-based reservoir monitoring could be expected through different alternatives such as multi-sensor image fusion, water level measurement with altimeters or interferometry, etc.

The Potential of Satellite SAR Imagery for Mapping of Flood Inundation

  • Lee, Kyu-Sung;Hong, Chang-Hee;Kim, Yoon-Hyoung
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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    • pp.128-133
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    • 1998
  • To assess the flood damages and to provide necessary information for preventing future catastrophe, it is necessary to appraise the inundated area with more accurate and rapid manner. This study attempts to evaluate the potential of satellite synthetic aperture radar (SAR) data for mapping of flood inundated area in southern part of Korea. JERS L-band SAR data obtained during the summer of 1997 were used to delineate the inundated areas. In addition, Landsat TM data were also used for analyzing the land cover condition before the flooding. Once the two data sets were co-registered, each data was separately classified. The water surface areas extracted from the SAR data and the land cover map generated using the TM data were overlaid to determine the flood inundated areas. Although manual interpretation of water surfaces from the SAR image seems rather simple, the computer classification of water body requires clear understanding of radar backscattering behavior on the earth's surfaces. It was found that some surface features, such as rice fields, runaway, and tidal flat, have very similar radar backscatter to water surface. Even though satellite SAR data have a great advantage over optical remote sensor data for obtaining imagery on time and would provide valuable information to analyze flood, it should be cautious to separate the exact areas of flood inundation from the similar features.

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