• Proceedings of the KSR Conference
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• 2003.05a
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• pp.321-325
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• 2003

The technology for the multi-dimensional terrain perspective view can be used as an important factors in planning and designing for the various construction projects. In this study, the stereo image perspective view has been generated for the multi-dimension analysis by combining useful digital map and remotely sensed satellite images. In the course of experimenting with the multi-dimensional topography generated by the combination of the front-projected image by the precise GCP and DEM from the contour line, the technology has been developed to offer the multi-dimensional access to the potential construction sites from the nearby main roads. This stereo image bird's eye view has made it possible to make multi-dimensional analysis on the terrain, which provides real time virtual access to the designated construction sites and will be a versatile application for development planning and construction projects.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.3
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• pp.1-8
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• 2002

The technology for the three-dimensional terrain perspective view can be used as an important factor in planning and designing for the various construction projects. In this study, the stereo image perspective view has been generated for the multi-dimension analysis by combining useful digital map and remotely sensed satellite images. In the course of experimenting with the three-dimensional topography generated by the combination of the orthopimage by the precise GCP and DEM from the contour line, the technology has been developed to offer the multi-dimensional access to the potential construction sites from the nearby main roads. This stereo image bird's eye view has made it possible to make multi-dimensional analysis on the terrain, which provides real-time virtual access to the designated construction sites and will be a versatile application for development planning and construction projects.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.115-120
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• 2003

일반적으로 광학위성은 궤도가 부정확하여 지상기준점(GCP)을 이용하여 궤도를 보정하는 작업을 수행한 후 수치 표고모형 자료(DEM)를 추출한다. 지상기준점은 실제 측량이나 지형도로부터 얻게 되지만, 이러한 작업이 불가능한 경우에는 광학영상으로부터 수치 표고 모형 자료를 추출할 수 없다. 본 연구에서는 수-수십 cm의 위성 궤도 정확도를 지니는 ESA ERS영상과 약 1Km의 해상도를 지니는 GTOPO-30 DEM을 이용하여 지상기준점을 추출 방법에 대해 연구하였다. 연구지역인 대전 주변에 대하여 지상기준점을 추출한 결과 경도 -0.348초, 위도 0.293초의 오차를 나타내었다. 또한 추출된 지상기준점을 이용하여 한 쌍의 SPOT 위성영상으로부터 DEM을 추출이 가능하였으며, 레이더 interferometry 기술을 이용한 지형고도 추출 및 변화 탐지에도 활용될 수 있음을 확인하였다.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.270-274
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• 2009

한반도의 정밀관측을 목적으로 개발된 KOMPSAT-2위성의 영상을 활용하기 위해서는 촬영 시 발생하는 기하학적 왜곡의 보정이 필요하다. 본 연구에서는 지상기준점(Ground Control Point: GCP) 선택의 세 가지 특성을 각각 적용하여 기하보정을 하였다. 보정 영상의 정확도 검정을 위하여 수치지도(digital map)를 이용한 평균제곱근오차(Root Mean Square Error: RMSE)와 육안검사를 통해 정확도를 비교하였다. 그 결과 영상의 중앙은 선형 교차점을 선택한 방법이 가장 정확하였고, 가장자리는 건물의 모서리 또는 건물의 중심을 선택한 방법이 우수하였다.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.164-170
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• 2012

This paper presents that the comparison results of AT (Active Transponder) positions obtained from different measurements: the result of GPS device and evaluated position from the SAR (Synthetic Aperture Radar) image, and active transponders can be useful as GCPs(Ground Control Points) in SAR images. The X-band AT are installed on the wide-and-flat area to improve SCR(signal-to-clutter ration), and activated to represent impulse response function in order to operate as one point target in SAR images. Cosmo-SkyMed operating at X-band frequency are used to provide SAR images of AT. The comparison of AT position is performed by using the result of GPS device field measurement and AT SAR images. ENVI-SARscape S/W is used to evaluate AT position in the SAR images. From the comparison, it is shown that AT are useful as GCPs for SAR images.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.3-9
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• 2016

UAV(unmanned aerial vehicle) can quickly produce orthoimage with high-spatial resolution and DSM(digital surface model) at low cost. However, vertical and horizontal positioning accuracy of orthoimage and DSM, which are obtained by UAV, are influenced by image processing techniques, quality of aerial photo, the number and position of GCPs(ground control points) and overlap in flight plan. In this study, effects of overlap and the number of GCPs are analyzed in orthoimage and DSM. Positioning accuracy are estimated based on RMSE(root mean square error) by using dataset of nine pairs. In the experiments, Overlaps and the number of GCPs have influence on horizontal and vertical accuracy of orthoimage and DSM.

• Korean Journal of Remote Sensing
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• v.40 no.4
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• pp.387-396
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• 2024

Most very high-resolution (VHR) satellite images provide rational polynomial coefficients (RPC) data to facilitate the transformation between ground coordinates and image coordinates. However, initial RPC often contains geometric errors, necessitating correction through matching with ground control points (GCPs). A GCP chip is a small image patch extracted from an orthorectified image together with height information of the center point, which can be directly used for geometric correction. Many studies have focused on area-based matching methods to accurately align GCP chips with VHR satellite images. In cases with seasonal differences or changed areas, edge-based algorithms are often used for matching due to the difficulty of relying solely on pixel values. However, traditional edge extraction algorithms,such as canny edge detectors, require appropriate threshold settings tailored to the spectral characteristics of satellite images. Therefore, this study utilizes deep learning-based edge information that is insensitive to the regional characteristics of satellite images for matching. Specifically,we use a pretrained pixel difference network (PiDiNet) to generate the edge maps for both satellite images and GCP chips. These edge maps are then used as input for normalized cross-correlation (NCC) and relative edge cross-correlation (RECC) to identify the peak points with the highest correlation between the two edge maps. To remove mismatched pairs and thus obtain the bias-compensated RPC, we iteratively apply the data snooping. Finally, we compare the results qualitatively and quantitatively with those obtained from traditional NCC and RECC methods. The PiDiNet network approach achieved high matching accuracy with root mean square error (RMSE) values ranging from 0.3 to 0.9 pixels. However, the PiDiNet-generated edges were thicker compared to those from the canny method, leading to slightly lower registration accuracy in some images. Nevertheless, PiDiNet consistently produced characteristic edge information, allowing for successful matching even in challenging regions. This study demonstrates that improving the robustness of edge-based registration methods can facilitate effective registration across diverse regions.

• Korean Journal of Remote Sensing
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• v.24 no.2
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• pp.133-140
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• 2008

In this paper, we analyzed the accuracy of orbit modeling with various control point configurations and adjustment unknown parameter sets. We used 152 GCP points acquired from GPS surveying, which were distributed from Choon-chun to Nha-ju along 420km in distance. For orbit modeling, seven adjustment parameter sets were chosen to include parameters for satellite position, velocity and attitude angles at different degree of freedom. Firstly we determined the location of model point in seven configurations. Secondly we estimated model parameters for each parameter set and for each GCP configurations. Finally we applied the model to reference check points and analyzed its accuracy. We were able to find the unknown parameter set that produce best orbit modeling performance regardless of the configuration of model points.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.275-275
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• 2019

기후변화에 따른 집중호우의 발생빈도와 강도가 증가하면서 대규모 홍수로 인한 인명 및 재산피해가 발생하고 있다. 그에 따라 홍수 상황을 신속하게 확보하고 홍수피해를 빠르게 예측하는 모니터링 기술이 필요하다. 최근 공간정보 분야에서 무인항공기 (UAV: Unmanned aerial vehicles)를 이용한 3차원 지형자료 확보 연구가 활발하게 이용되고 있다. 무인항공기는 지형자료 구축 뿐 만 아니라 홍수 시 신속한 홍수 모니터링이 가능하기 때문에, 본 연구에서는 무인항공기를 이용하여 홍수 전 지형자료 구축을 비롯하여, 홍수 시 모니터링, 홍수 후 지형자료 구축에 이르기까지 UAV를 이용한 홍수 모니터링 기술을 소개한다. 연구대상지는 금강 합류 직전 논산천 하류 1 km 지점으로, UAV를 이용한 지형자료를 구축하기 이전에 좌표 매칭을 위한 GCP (Ground Control Point ) 측량을 실시하고, UAV 비행계획을 수립하고 촬영한다. 촬영된 영상을 GCP좌표와 소프트웨어 (Pix4D)를 이용하여 정사영상과 DSM(Digital Surface Model)자료를 구축한다. 홍수시 UAV를 이용한 촬영을 통하여 동영상은 수재해 플랫폼에 송신하고, 이미지 영상은 홍수 전 영상처리와 동일한 방법을 이용하여 지형 자료를 구축하여, 홍수시 침수심이나 지형변화를 분석한다.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.2
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• pp.11-23
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• 2000

The subjects of this study are to examine and to apply the methods of making 1 : 10,000 scale digital maps using Russian's 2 m resolution satellite images of Alternative and 8 m resolution stereo satellite images of MK-4 for the Kyoha area of Paju-city where aerial-photo surveying is not possible. A digital elevation model (DEM) was calculated from MK-4 images. With this DEM, the Alternative images were orthorectified. Ground control points (GCP) were acquired from GPS surveyings and were used to perform geometric corrections on Alternative images. From field investigation, thematic attributes are digitized on the monitor. RMS errors of the planar and vertical positions are estimated to ${\pm}0.4$ m and ${\pm}15$ m, respectively. The planar accuracy is better than an accuracy required by NGIS (national GIS) programs. Local information from field investigation was added and the resulting maps should be good as base maps for, such as, regional and urban plannings.