• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.359-365
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• 2004

Data integration techniques are becoming increasing1y important for conquering a limitation with a single data. Image fusion which improves the spatial and spectral resolution from a set of images with difffrent spatial and spectral resolutions, and image registration which matches two images so that corresponding coordinate points in the two images correspond to the same physical region of the scene being imaged have been researched. In this paper, we compared with six image fusion methods(Brovey, IHS, PCA, HPF, CN, and MWD) with panchromatic and multispectral images of IKONOS and developed the registration method for applying to SPOT-5 satellite image and RADARSAT SAR satellite image. As the result of tests on image fusion and image registration, we could find that MWD and HPF methods showed the good result in term of visual comparison analysis and statistical analysis. And we could extract patches which depict detailed topographic information from SPOT-5 and RADARSAT and obtain encouraging results in image registration.

• Korean Journal of Remote Sensing
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• v.13 no.1
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• pp.57-73
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• 1997

This paper is related to the correction of radiometric distortions induced by topographic relief. RADARSAT SAR image data were obtained over the mountainous area near southern part of Seoul. Initially, the SAR data was geometrically corrected and registered to plane rectangular coordinates so that each pixel of the SAR image has known topographic parameters. The topographic parameters (slope and aspect) at each pixel position were calculated from the digital elevation model (DEM) data having a comparable spatial resolution with the SAR data. Local incidence angle between the incoming microwave and the surface normal to terrain slope was selected as a primary geometric factor to analyze and to correct the radiometric distortions. Using digital maps of forest stands, several fields of rather homogeneous forest stands were delineated over the SAR image. Once the effects of local incidence angle on the radar backscatter were defined, the radiometric correction was performed by an empirical fuction that was derived from the relationship between the geometric parameters and mean radar backscatter. The correction effects were examined by ground truth data.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.103-112
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• 2012

We demonstrate the preliminary results of ship detection application using synthetic aperture radar (SAR) and automatic identification system (AIS) together. Multi-frequency and multi-temporal SAR images such as TerraSAR-X and Cosmo-SkyMed (X-band), and Radarsat-2 (C-band) are acquired over the West Sea in South Korea. In order to compare with SAR data, we also collected an AIS data. The SAR data are pre-processed considering by the characteristics of scattering mechanism as for sea surface. We proposed the "Adaptive Threshold Algorithm" for classification ship efficiently. The analyses using the combination of the SAR and AIS data with time series will be very useful to ship detection or tracing of the ship.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.3
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• pp.1-12
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• 2007

This study was conducted in order to analyze a flooded area by the overflow of a stream using hydrological and hydraulic models and to estimate the utility of the SAR satellite image by comparing a protected lowland inundation area with a past inundation area map. The research area selected for this study is Sapkyocheon, which was flooded in August 1999. The flood stage was analyzed to select an inundation area by applying flood events in August 1999. By importing analyzed flood stage data into TIN data of WMS, the inundation area of a protected lowland was selected and then compared with an flood hazard map of WAMIS. An inundation area is selected by the SAR satellite image in comparing the image of August 4, 1999 (inundation time) with the image of September 8, 2002 (after inundation). The method of selecting an inundation area with the hydraulic model of HEC-RAS can be used to select an inundation area of external overflow, but it has the limit of selecting an inundation area concerning the internal drainage. The method of using the SAR satellite image can complement the limit of an inundation area of an internal drainage but accuracy of inundation area depends on using SAR satellite image acquired at time of maximum depth.

• Proceedings of the KSRS Conference
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• 2001.03a
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• pp.9-14
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• 2001

오랜 기간동안 진행되는 사회간접자본 건설의 진행 상황을 관측하는 것은 대규모 공사의 종합적인 관리를 위해 필수불가결한 요소이다. 동북아 지역의 중추 공항 기능을 담당할 영종도 국제공항의 공사진행 과정을 관측하기 위하여 인공위성 영상 자료가 활용되었다. 바다위에 건설되는 공항의 특성으로 인하여 방조제 건설과 매립공사가 수행되었다. 활주로, 유도로, 여객터미널과 복합교통센터 등이 건설되었으며, 공항의 건설로 산림이 훼손되고 양식장과 염전이 매립되는 것이 관측되었다. 이러한 공항공사의 진척상태를 분석하기 위해서 시계열 Landsat TM 영상을 사용하였으며, 타 위성영상에서는 공항의 공사현황이 어느정도 분석가능한지를 가늠하기 위해서 KOMPSAT EOC, IRS-1C PAN, RADARSAT SAR 영상이 활용되었다. 시계열 Landsat TM 영상에서는 공항 부지의 매립 진척 현황과 산림의 벌채 등을 잘 분석할 수 있었다. KOMPSAT EOC 과 IRS-1C PAN 영상은 높은 공간해상력으로 건설에 사용된 가건물과 같은 세부적인 시설물을 관측할 수 있었다. 15m PAN 영상을 제공하는 Landsat ETM은 IHS 합성 후 분석하였는데, 기존의 TM 영상에서 분류하지 못했던 방조제의 도로와 성토를 구분할 수 있었다. RADARSAT SAR 영상에서는 광학영상에서 볼 수 없었던 독특한 정부 를 얻을 수 있었다.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.74-79
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• 2014

Conventional ScanSAR mode has been adopted in Envisat or Radarsat and played an important role to acquire wide swath SAR images for environmental surveillance. However, it suffers from the undesirable scalloping effect caused by non-homogeneity of antenna pattern while the image resolution is sacrificed. In recent years, TOPS mode has been suggested and put into use to overcome the disadvantages of the conventional scanning mode. Although TOPS mode is able to produce wide-swath SAR image in a short time interval, it demands highly complicated system design knowledge. In this paper, we present the operation principle of TOPS mode and a full SAR simulation is performed to generate TOPS SAR raw data. Azimuth antenna pattern is modified during TOPS mode operation and it is shown that the undesired scalloping effect is suppressed in the generated SAR image.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.188-191
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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.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.300-305
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• 2005

To trace the flood inundation area around rural small stream, RADARSAT image was applied because it has the ability of acquiring data during storm period irrespective of rain and cloud. For the storm of 9 August, 1998 in Anseong-cheon watershed, three temporal RADARSAT images before, just after and after the storm were used. After ortho-rectification using 5 m DEM, two methods of RGB composition and ratio were tried and found the inundated area in the tributary stream, Seonghwan-cheon and Hakseong-cheon. The inundated area had occurred at the joint area of two streams, thus the floodwater overflowed bounding discharge capacity of the stream. The progression of damage areas were stopped by the local road and farm road along the paddy.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.155-168
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• 1996

Speckle noise has been a primary concern to many applications of synthetic aperture radar (SAR) imagery. In recent years, several satellites with radar imaging systems were launched and the use of SAR data are expected to be increased rapidly The objectives of this study are to provide introductory understanding on radar speckle filtering and to compare the effects of several filtering methods that are relatively unknown to user community. Two study sites were extracted from the RADARSAT SAR data obtained over the suburban areas near Seoul. The study sites include relatively homogeneous cover types, such as reservoir, parking lot, rice pad, and deciduous forest. Five filters (mean filter, median filter, sigma filter, local statistics filter, and autocorrelation filter) were applied to the SAR imagery and their effects were evaluated from the aspects of both image smoothing and edge preservation. In overall, the evaluation results indicate that the local statistics filter and autocorrelation filter, that are based on a speckle model, are more effective to suppress speckle within homogeneous cover type while maintaining the edge sharpness between cover types.

• Korean Journal of Remote Sensing
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• v.19 no.6
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• pp.421-430
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• 2003

The extraction technique for Doppler information(Doppler centroid frequency(f$_{dc}$) and it's rate(f$_{r}$) is very important to make an image from the radar echo signal data. Clutterlock and auto-focusing techniques have been widely used to extract accurate Doppler information. But both techniques are not easy to implement in SAR processor and need quite lots of time to calculate accurate f$_{dc}$ and f$_{r}$ because they are generally based on echo signal data only. In this paper we suggest hybrid method for Doppler extraction using both of echo signal data and orbital and attitude information of satellite. In this method CDE(Correlation Doppler Estimation) technique is only used to estimate exact modular f$_{dc}$ using received echo signal data and rest of other algorithms are based on simple mathematical model of geometry between satellite and ground targets as well as the Doppler frequency ambiguity resolving problem. The experimental results using Radarsat-1 signal data shows that the proposed method can be effectively used for the extraction of Doppler information.