• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.431-444
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• 2014

As applications of spaceborne SAR imagery are extended, there are increased demands for accurate registrations for better understanding and fusion of radar images. It becomes common to adopt multi-resolution SAR images to apply for wide area reconnaissance. Geometric correction of the SAR images can be performed by using satellite orbit and attitude information. However, the inherent errors of the SAR sensor's attitude and ground geographical data tend to cause geometric errors in the produced SAR image. These errors should be corrected when the SAR images are applied for multi-temporal analysis, change detection applications and image fusion with other sensor images. The undesirable ground registration errors can be corrected with respect to the true ground control points in order to produce complete SAR products. Speeded Up Robust Feature (SURF) technique is an efficient algorithm to extract ground control points from images but is considered to be inappropriate to apply to SAR images due to high speckle noises. In this paper, an attempt is made to apply SURF algorithm to SAR images for image registration and fusion. Matched points are extracted with respect to the varying parameters of Hessian and SURF matching thresholds, and the performance is analyzed by measuring the imaging matching accuracies. A number of performance measures concerning image registration are suggested to validate the use of SURF for spaceborne SAR images. Various simulations methodologies are suggested the validate the use of SURF for the geometric correction and image registrations and it is shown that a good choice of input parameters to the SURF algorithm should be made to apply for the spaceborne SAR images of moderate resolutions.

• Journal of Cadastre & Land InformatiX
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• v.46 no.2
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• pp.183-196
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• 2016

Ground control points are needed for precision geometric correction of satellite images, and the coordinates of a high-quality ground control point can be obtained from the GPS measurement. However, considering the GPS measurement requires an excessive amount o f t ime a nd e fforts, there is a need for coming up with an alternative solution to replace it. Therefore, we examined the possibility of replacing the existing GPS measurement with coordinates available at online maps to acquire the coordinates of ground control points. To this end, we examined error amounts between the coordinates of ground control points obtained through Daum Map API, and them compared the accuracies between three types of coordinate transformation equations which were used for geometric correction of satellite images. In addition, we used the coordinate transformation equation with the highest accuracy, the coordinates of ground control point obtained through the GPS measurement and those acquired through D aum M ap A PI, and conducted geometric correction on them to compare their accuracy and evaluate their effectiveness. According to the results, the 3rd order polynomial transformation equation showed the highest accuracy among three types of coordinates transformation equations. In the case of using mid-resolution satellite images such as those taken by Landsat-8, it seems that it is possible to use geometrically corrected images that have been obtained after acquiring the coordinates of ground control points through Daum Map API.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.159-160
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• 2017

본 논문에서는 무인기를 통해 수집한 영상을 과학적 분석 및 매핑이 가능한 영상으로 산출하는 자동 기하보정 시스템을 제안한다. 해당 시스템은 무인기를 활용하여 상시적으로 재난 상황을 촬영하여 감시 및 분석을 하며, 무인기에 탑재된 다중복합 센서 데이터의 실시간 처리 분석을 통해 국지적 홍수 재난의 감지 예측 및 상황대응을 지원하고, 통합경보 시스템과 연동하여 대국민 재난 정보를 제공하는 서비스를 위한 요소 기술이다. 현재 본 서비스를 제공할 수 있는 Front to End 시스템이 개발 완료되어 실제 필드에서의 재난 감시 및 예측 성능을 검증하기 위한 필드 테스트를 준비 중에 있다. 이에 본 논문에서는 현재 구축하고 있는 홍수 재난 관리 플랫폼에 대한 내용을 간단히 소개하고, 중요한 기능중 하나인 무인기 촬영 영상의 자동기하보정 시스템에 대해서 논한다.

• The Journal of the Korea Contents Association
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• v.6 no.6
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• pp.1-8
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• 2006

This paper presents an intelligent pattern matching method that can be used to acquire the reliable calibration data for automatic PCB pattern inspection. The inaccurate calibration data is often acquired by geometric pattern variations and selecting an inappropriate model manual. It makes low the confidence of inspection and also the inspection processing time has been delayed. In this paper, the geometric features of PCB patterns are utilized to calculate the accurate calibration data. An appropriate model is selected automatically based on the geometric features, and then the calibration data to be invariant to the geometric variations(translation, rotation, scaling) is calculated. The method can save the inspection time unnecessary by eliminating the need for manual model selection. As the result, it makes a fast, accurate and reliable inspection of PCB patterns.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.565-570
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• 2004

우리나라는 1960년대부터 산업발전과 함께, 급속한 도시화가 이루어졌다. 현재 활용 가능한 위성영상은 1975년 이후에 얻어진 영상이기 때문에 미국에서 1995년 일반에 공개된 DSI (Declassified Satellite Imagery) 영상은 1960년대 한반도의 지형정보를 제공하는 유일한 위성영상 자료이며 DSI 중 해상포가 2m 급에 이르는 CORONA 영상은 도시, 산림 환경의 변화를 탐지하는데 매우 유용하다. 본 논문에서의 과거의 한반도를 영상지도로 만들기 위해 모자이크 영상을 제작하였으며 모자이크 영상을 제작하기 위한 기하보정 방법에 대해 비교 분석하였다. 또한 최근 공개된 KH-9 영상을 기하보정하고 정확도를 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.834-841
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• 2004

There can be lips transformed geometrically in the lip images according to the location or the pose of camera and speaker. This transformation of the lip images changes geometric information of original lip phases. Therefore, for enhancing global lip information by using partial information of lips to correct lip phases transformed geometrically, in this paper we propose a method that can geometrically correct lips. The method is composed of two steps - the feature-deciding step and the correcting step. In the former, it is for us to extract key points and features of source image according to the its lip model and to create that of target image according to the its lip model. In the latter, we decide mapping relation after partition a source and target image based on information extracted in the previous step into each 4 regions. and then, after mapping, we unite corrected sub-images to a result image. As experiment image, we use fames that contain pronunciation on short vowels of the Korean language and use lip symmetry for evaluating the proposed algorithm. In experiment result, the correcting rate of the lower lip than the upper lip and that of lips moving largely than little was highly enhanced.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.141-150
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• 2011

Precise image-to-image registration is required to process multi-sensor data together. The purpose of this paper is to develop an algorithm that register between high-resolution optical and SAR images using linear features. As a pre-processing step, initial alignment was fulfilled using manually selected tie points to remove any dislocations caused by scale difference, rotation, and translation of images. Canny edge operator was applied to both images to extract linear features. These features were used to design a cost function that finds matching points based on their similarity. Outliers having larger geometric differences than general matching points were eliminated. The remaining points were used to construct a new transformation model, which was combined the piecewise linear function with the global affine transformation, and applied to increase the accuracy of geometric correction.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.251-254
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• 2004

최근 인공위성 영상자료의 해상도가 높아짐에 따라 영상을 통해 얻을 있는 정보의 양이 증가하고 있다. 영상의 식별력이 증가함으로써 영상에서 얻을 수 있는 정보량이 증가하지만 그와 함께 정보의 질이 향상되었다고 판단하기는 어렵기 때문에 지형과 영상의 정밀보정은 매우 중요하다 특히, 광학센서 기반의 인공위성 자료는 영상자료의 공간해상도 뿐만 아니라 촬영시기, 지형형태 둥 많은 내ㆍ외부 조건에 따른 특성을 가지고 있다. 이러한 특성은 표고가 높은 지형에서 더욱 크게 영향 받는다. 이에 본 연구에서는 Kompsat EOC 및 Spot-5 등 다양한 광학위성 센서에 대한 지형효과 특성을 위성의 기하정보 등록방법에 따라 분석함으로써 자료 이용의 효용성 제고에 기여하고자 한다.

• Korean Journal of Remote Sensing
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• v.14 no.2
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• pp.137-148
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• 1998

An algorithm developed for the precision correction of high resolution satellite images is introduced in this paper. In general, the polynomial warping algorithm which derives polynomial equations between GCPs extracted from an image and a base map requires many GCPs well-distributed over the image. The precision correction algorithm described in this paper is based on a sensor-orbit-Earth geometry, and therefore, it is capable of correcting a raw image using only 2-3 GCPs. This algorithm estimates the errors on the orbit determination and the attitude of the satellite by using a Kalman filter. This algorithm was implemented, tested and integrated into the KITSAT-3 image preprocessing software.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.319-322
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• 2006

2002년 5월 촬영이 시작된 SPOTS 영상은 공간해상도가 2.5mX2.5m로 고해상도이면서도 촬영폭이 광역적이어서 다양한 활용이 가능하다. SPOT5영상을 보다 유용하게 활용하기 위해서는 단순 기하보정 보다는 높은 정확도를 얻을 수 있는 정사보정이 요구된다. 보정영상의 정확도에 영향을 미치는 요소로는 지형, GCP, DEM등이 있다. 본 연구에서는 다른 조건들은 동일하게 하고, 자료 구축에 많은 시간이 소요되는 DEM(수치표고모델)의 축척만을 달리하여 보정 영상의 정확도를 비교하였다. 그 결과 DEM의 축척 변화가 보정 영상에 미치는 영향은 미비한 것으로 나타났다. 따라서 작업의 효율성을 고려할 경우에 소축척의 DEM을 사용하는 것이 바람직하다.