• Information and Communications Magazine
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• v.31 no.2
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• pp.44-51
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• 2014

본 논문에서는 초다시점 (Super Multi-view) 영상 합성을 위한 영상 기반의 온라인 삼차원 복원 기술들을 소개한다. 복원의 정확성을 높이고자 하는 방법은 크게 두 부류로 나뉜다. 먼저 재투영 오차를 비용 함수(Cost function)으로 정의하고, 이를 Bundle Adjustment로부터 최적화를 수행하는 방법과 카메라의 위치와 삼차원 복원 결과에 대해 확률적인 분포를 정의하고 이를 순차적으로 추정하는 확률적인 필터링(Stochastic filtering)에 기반한 방법이 존재한다. 본 논문에서는 두 방법의 장단점을 분석하고, 이로부터 새로운 확률적 필터링에 기반한 3차원 복원 및 카메라 위치 추정 방법을 제안한다. 이로부터 대공간 환경에 적용하여 성능을 검증한다.

• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.13-22
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• 2005

Similarly to the edges defined in a 2D image, we can define the geometric features representing the boundary of the distinctive parts appearing on 3D meshes. The geometric features have been used as basic primitives in several applications such as mesh simplification, mesh deformation, and mesh editing. In this paper, we propose geometric livewire and geometric livelane for extracting geometric features in a 3D mesh, which are the extentions of livewire and livelane methods in images. In these methods, approximate curvatures are adopted to represent the geometric features in a 3D mesh and the 3D mesh itself is represented as a weighted directed graph in which cost functions are defined for the weights of edges. Using a well-known shortest path finding algorithm in the weighted directed graph, we extracted geometric features in the 3D mesh among points selected by a user. In this paper, we also visualize the results obtained from applying the techniques to extracting geometric features in the general meshes modeled after human faces, cows, shoes, and single teeth.

• Journal of the Korean Society of Radiology
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• v.81 no.1
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• pp.70-80
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• 2020

Currently, there has been an increase in the use of surgical modalities to treat lymphedema and MR imaging to examine lymphatic vessels. Furthermore, there have been several advancements in the field of MR imaging, from the traditional heavily T2-weighted images to three-dimensional images. Three-dimensional images include spoiled gradient echo images, and numerous advanced techniques have been implemented. Among the fat suppression techniques, mDixon technique has recently been in the spotlight.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.559-564
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• 2004

최근들어 광범위한 지역의 삼차원 국토정보 취득을 위한 고해상도 위성영상의 센서모형화 기법에 관한 연구가 활발히 진행되고 있다. IKONOS나 SPOT 5호와 같은 고해상도 위성영상의 모형화에 앞서 본 연구에서는 각종 응용분야에서 광범위하게 활용되고 있는 SPOT 3호 위성영상을 대상으로 지상기준점을 이용하여 경사촬영(off-nadir viewing)각을 추정하는 기법을 개발하였다. 추정된 경사촬영각은 영상좌표를 보정하는데 사용되었으며 2차원 부등각사상변환을 이용하여 기존의 모형화 방법 보다 간결하고 정확도가 향상된 모형화 기법을 제안하였다. 또한, 기존의 엄밀 센서 모형화 방법을 대체하고 있는 위성영상의 센서모형화를 위한 다양한 방법들이 제안되고 있기 때문에, 2차원 부등각사상변환, 직접선형변환(DLT), 자체검정-DLT(SDLT)등의 추상화된 모형화 방법을 SPOT 위성영상에 대해 기준점 수의 변화에 따라 검사점을 이용하여 수평성분, 수직성분으로 나누어 정확도를 비교 분석하였다.

• The korean journal of orthodontics
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• v.41 no.4
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• pp.255-267
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• 2011

Objective: The purpose of this study was to confirm the reliability of a cone beam computed tomography (CBCT)-generated panoramic view based on a CBCT 3D image and to find the most helpful 2D panoramic image compared with CBCT 3D image when examining the mesiodistal tooth axis. Methods: A test model was constructed according to cephalometric norms. The test model was repeatedly repositioned for CBCT and panoramic radiographic imaging. Panoramic radiographs were acquired at each of the following 3 occlusal plane positions: $-5^{\circ}$, $0^{\circ}$, and $+5^{\circ}$. Measurements of mesiodistal tooth axis in CBCT 3D image, CBCT-generated panoramic view, and panoramic radiographs were compared. Results: Compared with the CBCT-generated panoramic view, CBCT 3D image showed significant difference in the mesiodistal tooth axis in the premolars and no significant difference in the mesiodistal tooth axis in the incisors and canines. Mesiodistal tooth axis on the CBCT-generated panoramic view was significantly different from that on panoramic radiographs. Conclusions: CBCT-generated panoramic view can be a useful tool for evaluating mesiodistal tooth axis.

• The Journal of the Korean dental association
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• v.45 no.6 s.457
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• pp.355-361
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• 2007

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.97-103
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• 2010

There are many algorithms for 2D to 3D graphic conversion technology which have the high complexity and large scale of iterative computation. So in this paper propose parallel algorithm and high speed graphics accelerator architecture using Park's MAMS(Multiple Access Memory System) for Phong Shading, one of many 3D algorithms. The Proposed SIMD processor architecture is simulated by HDL and simulated and got 30 times faster result. It means any kinds of 3D algorithm can make parallel algorithm and accelerated by SIMD processor with Park's MAMS for real time processing.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.1
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• pp.41-48
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• 2009

This Paper introduces representation and coding schemes of multiview texture and depth data for complex three-dimensional scenes. We represent input color and depth images using compressed texture and depth map pairs. The proposed X-codec encodes them further to increase compression ratio in a near-lossless way. Our system resolves two problems. First, rendering time and output visual quality depend on input image resolutions rather than scene complexity since a depth image-based rendering techniques is used. Second, the random access problem of conventional image-based rendering could be effectively solved using our image block-based compression schemes. From experimental results, the proposed approach is useful to graphics applications because it provides multiview rendering, selective decoding, and scene manipulation functionalities.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.36-45
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• 2006

Three-dimensional (3-D) texture coordinates mean the position information of torture segments that are mapped into polygons in a 3-D mesh model. In order to compress texture coordinates, previous works reused the same linear predictor that had already been employed to code geometry data. However, the previous approaches could not carry out linear prediction efficiently since texture coordinates were discontinuous along a coding order. Especially, discontinuities of texture coordinates became more serious in the 3-D mesh model including a non-atlas texture. In this paper, we propose a new scheme to code 3-D texture coordinates using as a texture image rearrangement. The proposed coding scheme first extracts texture segments from a texture. Then, we rearrange the texture segments consecutively along the coding order, and apply a linear prediction to compress texture coordinates. Since the proposed scheme minimizes discontinuities of texture coordinates, we can improve coding efficiency of texture coordinates. Experiment results show that the proposed scheme outperforms the MPEG-4 3DMC standard in terms of coding efficiency.

• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.77-85
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• 1996

Using a series of medical tomograms, we can reconstruct internal organs or other objects of interest and generate 3-D images. It is generally accepted that the axial resolution determined by two sequential image slices is lower than the planar resolution in one image slices. Therefore, various methods of interpolation were developed for an accurate display of reconstructed images. In this paper, a new algorithm for 3-D reconstruction of the medical images such as MRI and X-ray CT is suggested. The algorithm is shape-based and utilizes parts of the gray-level information. We extend the conventional shape-based interpolation of the binary images to the gray-scale images using the shortest distance map. Using this new algorithm, We could reduce the execution time for interpolation while keeping similar high quality of the reconstructed images with reduced execution time and is applicable to the various medical tomograms.