• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.297-304
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• 2004

In this paper, a mesh simplification algorithm based on wavelet transform and 2D planar sampling is proposed for efficient handling of 3D objects in computer applications. Since 3D vertices are directly transformed with wavelets in conventional mesh compression and simplification algorithms, it is difficult to solve tiling optimization problems which reconnect vertices into faces in the synthesis stage highly demanding vertex connectivities. However, a 3D mesh is sampled onto 2D planes and 2D polygons on the planes are independently simplified in the proposed algorithm. Accordingly, the transform of 2D polygons is very tractable and their connection information Is replaced with a sequence of vertices. The vertex sequence of the 2D polygons on each plane is analyzed with wavelets and the transformed data are simplified by removing small wavelet coefficients which are not dominant in the subjective quality of its shape. Therefore, the proposed algorithm is able to change the mesh level-of-detail simply by controlling the distance of 2D sampling planes and the selective removal of wavelet coefficients. Experimental results show that the proposed algorithm is a simple and efficient simplification technique with less external distortion.

• Korean Journal of Optics and Photonics
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• v.27 no.2
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• pp.61-66
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• 2016

We used transmission deflectometry to measure the three-dimensional shapes of optical components, and we used the Hilbert transform to retrieve the phases from measured deformed fringe images. Deflectometry is useful for measuring large-scale samples, and specular samples. We have retrieved the phases from deformed fringe images and Hilbert-transformed images, and have used the least-squares method to find the height information. We have verified that phase retrieval using Hilbert transform is useful by computer simulation and experiment.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1996.06a
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• pp.79-109
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• 1996

In order to transform the underground utility data into the 3-D spatial objects, this thesis defined the type of the 3-D spatial objects and the storage structure of objects, and developed the spatial data transformation system that transforms the 2-D underground utility data into the pre-defined 3-D spatial objects through the Booch Method, an object-oriented development method. For this sake, the relational data model of ARC/INFO and the storage structure are analyzed, as well as the pre-requisites, required for the 3-D visualization of the underground utilities. Also, the 2-D underground utility data, saved in ARC/INFO, were transformed into the ASCII files through the internal pre-processing procedure, then used as the input data of the transformation system. In addition, to develop the transformation system, the object-oriented development methods are studied first and, then, applied to the system analysis and the design procedure with the Booch Method as a development method. Finally, the results of analysis and design procesure are implemented through AML, a ARC/INFO macro language, and C++, an object-oriented programing language. As a result of this study, the 3-D spatial objects that can visualize the 2-D utilities in 3-D, are acquired, and the adaptation of object-oriented development method to the system development procedure enabled an effective development prodedure.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1605-1606
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• 2006

본 논문에서는 집적 영상에 기반한 2차원/3차원 변환 가능한 디스플레이에서 기초 영상을 표시하는 투과형 디스플레이 소자로서 기존의 광변조기 대신 LCD (liquid crystal display) 패널을 사용하여 컬러 디스플레이를 구현하는 방법을 제안한다. 본 논문에서는 제안된 방법의 원리를 설명하고 실험 결과를 보여주도록 하겠다. 또한 예상되는 색 분산 문제점에 대하여 살펴보고 이의 원인을 분석하고 해결 방법을 제안하여 2차원/3차원 변환 가능한 컬러 디스플레이를 구현하는 방법에 대하여 논하도록 하겠다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.75-81
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• 2008

오늘날 정부기관, 지자체 그리고 민간 기업 에서 3차원 지리정보데이터에 대한 필요성이 증가하고 있어 그에 대한 연구가 활발히 이루어지고 있다. 이러한 연구의 결과로 국내에서 3차원 지리정보 데이터 포맷인 3DF-GML(3DFeature-GML)이 개발되었다. 하지만 3DF-GML의 데이터는 기존의 Shape 파일만을 사용하여 구축되기 때문에 활용성에 제한을 받고 있다. 또한 제작 및 수정 시에는 제한된 애플리케이션 활용만이 허용된다. 이에 따라 3DF-GML의 활용성을 높이기 위해 국내의 데이터뿐 만이 아니라 국외에서 제작되어진 3차원 지리정보 데이터 포맷의 데이터를 활용할 수 있는 방안이 필요하다. 본 논문에서는 국내의 3차원 지리정보 포맷(3DF-GML)과 국외의 3차원 지리정보 포맷들간의 데이터 포맷을 비교 및 분석한다. 이러한 분석은 국외 3차원 지리정보 포맷의 데이터 활용 및 호환을 유도하는 것이 가능하다. 따라서 본 논문에서는 국내 3차원 지리 정보데이터(3DF-GML)와 국외 3차원 지리정보 데이터 간의 변환 규칙 및 방법을 제시한다.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.3
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• pp.120-126
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• 2005

This paper presents the 3D wavelet based video compression system using quad-tree algorithm. The 3D wavelet based video compression system removes the temporal correlation of the input sequences using the motion compensation filter and decomposes the spatio-temporal subband using the spatial wavelet transform. The proposed system allocates the higher bit rate to the low frequency image of the 3D wavelet sequences and improves the 0.64dB PSNR performance of the reconstructed image in comparison with that of H.263. In addition to the limitation on the propagation of the motion compensation error by the 3D wavelet transform, the proposed system progressively transmits the input sequence according to the resolution and rate scalability.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.14-19
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• 2007

2차원 웨이블릿이나 3차원 웨이블릿 변환은 주파수 방향으로 나타나는 분광특성을 고려할 수 있는 장점이 있다. 그러나 다중분광 영상에서 3차원 웨이블릿 변환을 이용하여 분류한 연구사례는 발표되거나 보고된 사례가 거의 없다. 따라서 본 연구에서는 기존의 전통적인 분류기법에 의한 처리결과를 제시하고 3차원 웨이블릿 변환 계수와 에너지 변수량들을 이용한 분류 처리결과를 분류 정확도 측면에서 비교하여 분석하였다. 3D 웨이블릿의 경우 공간적인 변화양상과 주파수에 따른 분광정보의 변화 양상을 동시에 알려주는 계수로 표현되기 때문에 본 연구의 처리 기법은 다양한 분광특성을 지니는 객체들이 조밀하고 복합적으로 구성되어 있는 도시지역의 고 해상도 위성영상자료에 효과적으로 적용될 수 있다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.149-158
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• 1998

The aim of this paper is to propose the technique of the two dimensional geodetic coordinates conversion between WGS84 and Bessel spheroids by the two-dimensional affine transformation modeling based on the UTM plane coordinates without the local geoid model which is essential to three dimensional coordinates conversion. Area of approximately $25\times{11}$ square km in the city of Inchon was selected as the test area. The transformation parameters were determined using the eleven triangulation control points in test area. And then, those paraneters were applied to the fifteen cadastral control points which selected as checking points for precision checking of transformation parameters. The average and standard deviations of the absolute values of the conversion residuals of checking points in latitude/longitude and N/E(UTM) and/or x/y(TM) are $\pm0.006"$$\pm0.013"$ and $\pm{17cm/}\pm{30cm}$ respectively. Also, coefficients for 7-parameters, 3-parameters and UTM model transformation computed according as sizes of transformed area, and then the transformed characteristics of checking points according to transformation methods analyzed synthetically.hetically.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.253-261
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• 1997

In general, the transformation of coordinates in GPS is carried out by 3 dimensional transformation method with 3-10 parameter. In korea, the coordinates of transformation points ware determined are adjusted in-dependently by planimetry and the height, and also the weight of observations were not properly applied to the adjustment. In this study, two different transformation methods are tested and analysed by the field test, and it is finally found that 2 dimensional method is more efficient way than 3 dimensional classical transformation method.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.560-574
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• 2011

Satellite images that have been obtained periodically and continuously are very effective data to monitor the changes of Earth's surface. Traditionally, the studies on change detection using satellite images have mainly focused on comparison between two results after analyzing two images respectively. However, the interests in researches to catch smooth trends and short duration events from continual multi-temporal images have been increased recently. In this study, we introduce and test an approach based on 3D wavelet transform to analyze the multi-temporal satellite images. 3D wavelet transform can reduce the dimensions of data conserving main trends. Also, it is possible to extract important patterns and to analyze spatial and temporal relations with neighboring pixels using 3D wavelet transform. As a result, 3D wavelet transform is useful to capture the long term trends and short-term events rapidly. In addition, we can expect to get new information through sub-bands of 3D wavelet transform which provide different information by decomposed direction.