• Korean Journal of Remote Sensing
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• v.31 no.5
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• pp.395-408
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• 2015

High-resolution satellite image mosaics are becoming increasingly important in the field of remote sensing image analysis as an essential image processing to create a large image constructed from several smaller images. In this paper, we present an automatic seamline extraction technique and the procedure to generate a mosaic image by this technique. For more effective seamline extraction in the overlap region of adjacent images, an NDVI-based seamline extraction technique is developed, which takes advantage of the computational time and memory. The Normalized Difference Vegetation Index(NDVI) is an index of plant "greeness" or photosynthetic activity that is employed to extract the initial seamline. The NDVI can divide into manmade region and natural region. The cost image is obtained by the canny edge detector and the buffering technique is used to extract the ranging cost image. The seamline is extracted by applying the Dijkstra algorithm to a cost image generated through the labeling process of the extracted edge information. Histogram matching is also conducted to alleviate radiometric distortion between adjacent images acquired at different time. In the experimental results using the KOMPSAT-2/3 satellite imagery, it is confirmed that the proposed method greatly reduces the visual discontinuity caused by geometric difference of adjacent images and the computation time.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.211-215
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• 2004

본 연구에서는 2개 이상의 지리 부호화된 영상병합 시 중복 영역의 연결 부분에서 발생하는 방사적 차이를 최소화하여 모자이크 접합선이 최소화하는 알고리즘을 구현하였다. 연구내용을 세부적으로 보면 초기 접합선 및 최적 접합선 탐색을 하는 접합선 추출 알고리즘 구현, 대상 영상의 전체적인 방사 값의 분포 특성을 정규화하는 전역 방사 보정을 위한 알고리즘 구현, 접합선을 자동 탐색하여 탐색된 접합선을 중심으로 단순 중복, 평균화, 블랜딩에 의한 모자이킹 알고리즘 구현이 본 연구의 핵심 내용이다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.483-497
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• 2018

Image mosaicking, which combines several images into one image, is effective for analyzing images and important in various fields of spatial information such as a continuous image map. The crucial processes of the image mosaicking are optimal seamline determination and color correction of mosaicked images. In this study, the overlap regions were determined by SURF (Speeded Up Robust Features) for image matching. Based on the characteristics of the edges extracted by Canny filter, seamline candidates were selected from classified edges with their characteristics, and the edges were connected by using Dijkstra algorithm. In particular, anisotropic filter and image pyramid were applied to extract reliable seamlines. In addition, it was possible to determine seamlines effectively and efficiently by utilizing building and road layers from digital maps. Finally, histogram matching and seamline feathering were performed to improve visual quality of the mosaicked images.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.1
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• pp.47-53
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• 2007

Satellite image mosaicking is essential for image interpretation and analysis especially for a large area such as the Korean Peninsula. This paper proposed the technique of automatic seam-line extraction and the method of creating image mosaic in automated fashion. The seam-line to minimize artificial discontinuity was extracted using Minimum Absolute Gray Difference Sum algorithm with constraint condition on search-area width and Canny Edge Detection algorithm. To maintain the radiometric balance among images acquired at different time epochs, we utilized Match Cumulative Frequency method. Experimental results showed that edge detection algorithm extracted the seam-lines significantly well along linear features such as roads and rivers.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.61-69
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• 2009

By the advent of the high resolution satellite imagery, a ground-coverage included by a single satellite image is decreased. By the reason, there are increasing needs in image mosaicking technology to use images to various GIS fields. This paper describes an edge-based seamline extraction algorithm using edge information such as rivers, roads, buildings for image mosaicking. For this, we developed a method to track and link discontinuous edges extracted by edge detection operator. To estimate the effectiveness of the proposed algorithm, we applied the algorithm to IKONOS, KOMPSAT-1 and SPOT-5 satellite images. The experimental results showed that the algorithm successfully dealts with discontinuities caused by geometric differences in two images.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.896-913
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• 2018

Seam finding algorithm is one of the most important techniques to construct the high quality 360 VR image. We found that some degradations, such as ghost effect, are generated when the conventional seam finding algorithms (for examples, Voronoi algorithm, Dynamic Programming algorithm, Graph Cut algorithm) are applied, because those make the inefficient masks which cross the body of main objects. In this paper, we proposed an advanced seam finding algorithm providing the efficient masks which go through background region, instead of the body of objects. Simulation results show that the proposed algorithm outperforms the conventional techniques in the viewpoint of the quality of the stitched image.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.2 s.29
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• pp.61-66
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• 2004

By the advent of the high-resolution Satellite imagery, there are increasing needs in image mosaicking technology which can be applied to various application fields such as GIS(Geographic Information system). To mosaic images, various methods such as image matching and histogram modification are needed. In this study, automated image mosaicking is performed using image matching method based on the multi-resolution wavelet analysis(MWA). Specifically, both area based and feature based matching method are embedded in the multi-resolution wavelet analysis to construct seam line.; seam points are extracted then polygon clipping method are applied to define overlapped area of two adjoining images. Before mosaicking, radiometric correction is proceeded by using histogram matching method. As a result, mosaicking area is automatically extracted by using polygon clipping method. Also, seamless image is acquired using multi-resolution wavelet analysis.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.664-666
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• 2002

기울기 연산자나 표면접합에 의한 윤곽추출과는 다른 본 논문에서는 확장과 수축방법론을 이용한 윤곽추출 및 잡음제거 방법론을 제안한다. 제안한 알고리즘은 전처리과정을 거친 후 확장과 수축 방법론을 적용함으로써 영상 윤곽 추출률을 높이고자한다 특히, 기존의 윤곽선 추출방법인 소벨과 프리위트알고리즘은 전처리과정인 미디안필터를 거친 후에 사용하였으며, 제안한 방법은 기존의 윤곽선 추출 필터를 거친 후에 사용하였다. 구체적으로 서술하면 확장알고리즘에서는 일정한 임계치를 초과하면 흰색으로 대치하였고, 수축 알고리즘에서는 검정색으로 대치했다. 기존의 잡음제거과정은 윤곽선의 손실은 없었으나 잡음제거가 소량 이루어졌으며, 제안한 방법에서는 약간의 윤곽선 손실을 보였으나 완전하게 잡음을 제거시킬 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2065-2071
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• 2011

The external quality factor ($Q_e$) is controlled by coupling condition between resonator and input/output ports in design of microwave filter. In this paper, we represent extracting method of external quality factor using phase response for resonator with input/output ports according to position of feed line from microstrip line resonator. The results regarding to position, coupling gap and line width for tapped line and coupled line structure are represented, and we got the exact $Q_e$ value from the this method. This results will be applied to coupled resonator filter design.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.281-288
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• 2009

In the paper, we try to develop the methodology for updating road networks of large-scale digital maps by using construction drawing data. For the purpose, it is pre-requite step to merge road networks detached in CAD drawing data. As such, tie points are identified in neighboring drawings and used for solving the parameters of 2D conformal transformation between drawings. Then, the merged road network in CAD data is transformed to the coordinate system of digital maps. In the process, IPs in the drawings are considered as control information and 2D affine transformation is selected for coordinate transformation. Through the experiments with real dataset, we can identify that the developed method is valid and generally applicable.