• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.121-128
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• 2003

사면관측 원리에 의해 획득되는 레이더 영상은 레이더파의 입사각도와 지표면의 경사도 및 방위각에 따라 기하학적 왜곡이 발생하게 된다. 전 국토의 70% 이상이 산악지형인 국내 여건을 감안한다면 레이더 영상의 정량적 활용을 위해서는 정밀한 기하보정이 반드시 필요하다. 본 연구에서는 RADSARSAT-1 SAR 영상에 대하여 세 가지 기하보정 방법을 적용하였다. 먼저 GCP 만을 이용한 단순기하보정을 수행하였고, 두번째로 위성의 자세와 위치정보 등을 이용하여 센서모델을 통한 보정을 하였다. 마지막으로 다양한 영상자료에 적용할 수 있는 RFM(Rational Function Model)을 이용하여 기하보정을 하였다. 이 세 가지 방법으로 기하보정된 레이더 영상의 위치정확도를 모의 레이더 영상과 비교 분석하였다. 또한 RFM을 이용한 보정결과를 검증하기 위하여 SIR-C 영상을 추가로 분석하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.423-431
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• 2008

The control surveying which aims at identifying the coordinate system of satellite images with that of ground is a repeatedly performed essential process to produce digital ortho - photos and it acts as the main factor to increase the production cost of the photos by duplicated budgets and redundant works when executing the projects for acquiring basic geographical information from high density satellite images. During the experimentation, an application system was established for producing a stereo image chip by the analysis of DPPDB file structure, the stereo image chip was produced with SPOT and IKONOS images, the analysis of 3D modeling accuracy was performed to secure the required accuracy and to present the optimal number and deployment of the control points, and a 3D modeling was performed for new SPOT images and lastly, 3D ground coordinates were extracted by the observation of the same points through the overlapping with the new images. As the results of the research, it is proved that the stereo image chip can be used as the ground controls through the accuracy analysis between the coordinates of the images and the ground, close results were obtained between the coordinates by the ground survey and those by the 3D modeling using new images and the observation of the same points, positional changes were not found during observing the same points, and the research presented the methodology for improving the process of the control survey by showing the availability of the image controls on the stereo image chip instead of the ground controls.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.380-383
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• 2003

지형공간에 대한 3차원 이상의 입체적인 지공간에 대한 시각화와 더불어 시시각각으로 변화하는 지형공간을 유지하기 위해서는 시공간에 존재하는 정부의 취득과 표현기법이 신속하고 다양한 정보의 분석과 정리가 필수적인 숙제로 인식되어가고 있다. 렬 연구에서는 농촌 및 산촌지역을 대상으로 수집한 위성영상과 국립지리원에서 제작한 수치지도를 이용해 정밀지형보정을 실시하고 DEM과 정사영상을 이용해 3차원 이상의 다차원적인 공간정보시뮬레이션을 제작한 것이다. 이러한 입체적인 조감도의 작성기술은 각 분야에서 널리 활용될 수 있는 매우 중요한 요소기술로 활용될 수 있어, 위성영상을 이용하여 기존의 수치지형도와의 결합을 통한 3차원 영상 지도의 제작을 시도하여 다차원적인 분석이 가능한 입체 영상 조감도를 작성하였으며, 비행 시뮬레이션 기법에 의한 가상적인 접근이 가능한 연구결과를 얻어냄으로써 지형공간정보의 고부가 콘텐츠 활용을 유도하도록 하였다.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1089-1100
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• 2018

In this paper, we analyze the feasibility of establishing a precise sensor model for high-resolution satellite imagery using unified control points. For this purpose, we integrated unified control points and the aerial orthoimages from the national land information map (http://map.ngii.go.kr/ms/map/NlipMap.do) operated by the National Geographic Information Institute (NGII). Then, we collected the image coordinates corresponding to the unified control point's location in the satellite image. The unified control points were used as observation data for establishing a precise sensor model. For the experiment, we compared the results of precise sensor modeling using GNSS survey data and those using unified control points. Our experimental results showed that it is possible to establish a precise sensor model with around 2 m accuracy when using unified control points.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.4
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• pp.211-218
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• 2019

The Ministry of Land, Infrastructure and Transport is planning to launch CAS-500 (Compact Advanced Satellite 500) 1 and 2 in 2019 and 2020. Satellite image information collected through CAS-500 can be used in various fields such as global environmental monitoring, topographic map production, analysis for disaster prevention. In order to utilize in various fields like this, it is important to get the location accuracy of the satellite image. In order to establish the precise geometry of the satellite image, it is necessary to establish a precise sensor model using the GCP (Ground Control Point). In order to utilize various fields, step - by - step automation for orthoimage construction is required. To do this, a database of satellite image GCP chip should be structured systematically. Therefore, in this study, we will analyze various techniques for automatic GCP extraction for precise geometry of satellite images.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.867-879
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• 2020

As the era of space technology utilization is approaching, the launch of CAS (Compact Advanced Satellite) 500-1/2 satellites is scheduled during 2021 for acquisition of high-resolution images. Accordingly, the increase of image usability and processing efficiency has been emphasized as key design concepts of the CAS 500-1/2 ground station. In this regard, "CAS 500-1/2 Image Acquisition and Utilization Technology Development" project has been carried out to develop core technologies and processing systems for CAS 500-1/2 data collecting, processing, managing and distributing. In this paper, we introduce the results of the above project. We developed an operation system to generate precision images automatically with GCP (Ground Control Point) chip DB (Database) and DEM (Digital Elevation Model) DB over the entire Korean peninsula. We also developed the system to produce ortho-rectified images indexed to 1:5,000 map grids, and hence set a foundation for ARD (Analysis Ready Data)system. In addition, we linked various application software to the operation system and systematically produce mosaic images, DSM (Digital Surface Model)/DTM (Digital Terrain Model), spatial feature thematic map, and change detection thematic map. The major contribution of the developed system and technologies includes that precision images are to be automatically generated using GCP chip DB for the first time in Korea and the various utilization product technologies incorporated into the operation system of a satellite ground station. The developed operation system has been installed on Korea Land Observation Satellite Information Center of the NGII (National Geographic Information Institute). We expect the system to contribute greatly to the center's work and provide a standard for future ground station systems of earth observation satellites.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.545-548
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• 2006

It's very difficult to acquire the accurate GCP(Ground Control Point) in the urban center and forest aerial photo because of occurring of irregular multi-path error. Thr purpose of this study is to apply the GPS and the EDM system for 3D orthophoto in the small areas. GCPs surveyed by accuracy triangulation from EDM after from triangulation points to a fiducial point at study area used to GPS. And I have a comment on how to use areal orthophoto for future 3D-GIS after 3D-Modelling using areal orthophoto. As the results, EDM surveying could resolve multi-path error according to GPS surveying and It is possible for using aerial orthophoto on the basis of the 3D-GIS database.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.159-159
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• 2020

하천환경조사는 하천의 전반적인 특성을 조사 분석하는 것으로 하천환경 조사결과는 하천관련사업의 기초자료로 사용된다. 하천환경조사의 기초조사에서는 현장답사를 통해 하천의 특성을 대략적으로 판단하고 하천 전구간의 물리적 구조와 식생의 분포, 중요 서식처 정보를 포함하는 RCS 지도(River Corridor Survey)를 작성한다. 기초조사를 위해서는 하천 전 구간에 대한 현장답사가 필요하기 때문에 많은 시간, 비용 그리고 인력이 필요하고, 육안 또는 사진을 통한 스케치로 이루어져 조사 결과가 정성적이고 작업자의 경험이나 능력에 따라 결과가 좌우된다는 한계가 있다. 따라서 하천환경조사를 좀 더 간편하고 과학적이며 경제적으로 조사하기 위해 최근 드론 영상을 이용한 조사 기술 개발에 대한 연구들이 증가하고 있다. 하지만 드론을 이용한 하천환경조사의 대부분은 RGB 영상을 이용하기 때문에 정밀한 하천환경 변화를 정량적으로 분석하는데 한계가 있다. 이를 극복하기 위한 대안으로 사람이 감지할 수 있는 빛의 영역 뿐 아니라 자외선과 적외선 영역의 분광특성을 이용하여 하천환경의 특성을 세밀하게 분류하는 것이 가능한 초분광센서를 드론에 탑재하여 하천환경을 조사하기 위한 기초 연구들이 시작되고 있다. 본 연구에서는 line scan 방식의 초분광센서를 드론에 탑재하여 초분광영상을 촬영하기 위한 드론 시스템을 구성하였고, 하나의 사진과 같이 초분광영상을 제작하기 위해 다양한 기하보정 기술을 적용하여 최적의 기하보정 방법을 제시하였다. 이를 위해 초분광영상의 기하보정은 각각의 초분광영상의 GCP와 대응점을 이용한 2차원 변환 방법 및 비선형 변환 방법을 적용하여 보정을 수행하였으며, 각 방법에 따른 정사보정 영상의 위치정확도를 검증하였다. 연구 결과 드론 기반의 초분광영상 촬영 및 기하 보정 방법을 제시하였다. 향후 하천환경조사 뿐만 아니라 다양한 분야의 원격탐사에 초분광영상을 활용하는데 도움이 될 것으로 기대한다.

• 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.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.53-62
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• 2016

In recent years, UAV Photogrammetry based on an ultra-light UAS(Unmanned Aerial System) installed with a low-cost compact navigation device and a camera has attracted great attention through fast and accurate acquirement of geo-spatial data. In particular, UAV Photogrammetry do gradually replace the traditional aerial photogrammetry because it is able to produce DEMs(Digital Elevation Models) and Orthophotos rapidly owing to large amounts of high resolution image collection by a low-cost camera and image processing software combined with computer vision technique. With these advantages, UAV-Photogrammetry has therefore been applying to a large scale mapping and cadastral surveying that require accurate position information. This paper presents experimental results of an accuracy performance test with images of 4cm GSD from a fixed wing UAS to demarcate parcel boundaries in agricultural area. Consequently, the accuracy of boundary point extracted from UAS orthoimage has shown less than 8cm compared with that of terrestrial cadastral surveying. This means that UAV images satisfy the tolerance limit of distance error in cadastral surveying for the scale of 1: 500. And also, the area deviation is negligible small, about 0.2%(3.3m²), against true area of 1,969m² by cadastral surveying. UAV-Photogrammetry is therefore as a promising technology to demarcate parcel boundaries.