• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.71-74
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• 2009

The data-flow paradigm has been employed in various application areas. It is particularly useful where large data-streams must be processed, for example in video and audio processing, or for scientific visualization. A video-based 3D reconstruction system should process multiple synchronized video streams. The system exhibits many properties that can be targeted using a data-flow approach that is naturally divided into a sequence of processing tasks. In this paper we introduce our concept to apply the data-flow approach to a multi-video 3D reconstruction system.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.377-382
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• 1994

In the conventional Fourier imaging method in MRI (Magnetic Resonance Imaging), intramotion such as pulsatile flow makes zipper-like artifact along the phase encoding direction. On the other hand, line-integral projection reconstruction (LPR) method has advantages such as imaging of short T2, object and reduction of the flow artifact by elimination of the flow-induced phase fluctuation. The LPR, however, necessarily requires time consuming filtering and back-projection processes, so that the reconstruction takes long time. To overcome the long reconstruction time of the LPR and to obtain the flow artifact reduction effect, we adopted phase corrected concentric square raster sampling (CSRS) method and improved its imaging performance. The CSRS is a fast reconstruction method which has the same properties with the LPR. In this paper, we proposed a new method of flow artifact reduction using the CSRS method. Through computer simulations and experiments, we verified that the proposed method can eliminate phase fluctuations, thereby reducing the flow artifact and re- markably shorten the reconstruction time which required long time in the LPR.

• 로봇학회논문지
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• 제10권3호
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• pp.146-153
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• 2015

In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

• 한국정보과학회논문지:시스템및이론
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• 제32권4호
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• pp.168-176
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• 2005

본 논문에서는 모델 기반으로 한 장의 사진으로부터 중점 정보를 포함한 선분을 이용하여 물체를 3차원 재구성하는 방법을 제안한다. 미리 정의된 다면체를 원시기하모델로 사용하며 한 장의 영상으로부터 복원을 시도하였다. 미리 정의된 다면체 모델을 원시기하모델로 사용하며 사용자가 원시기하모델(primitive)의 각 대응점(correspondence point)을 사진에 매핑 시키는 것으로서 3차원 재구성이 수행된다. 기존의 모델기반 3차원 재구성은 카메라 파라미터들을 복원하거나 반복(iteration)을 통한 오차최소화 기법을 사용하였다. 하지만 본 논문은 원시기하모델에 포함되어 있는 선분들과 그 선분들의 중점 정보로부터 선분을 3차원 복원하며 복원된 선분들로부터 원시기하모델을 재구성하는 방법을 제안한다. 이러한 방법은 선분을 복원하는 단계에서 요구되는 최소한의 카메라 파라미터(focal length) 만으로 원시기하모델을 재구성 할 수 있다.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.51-56
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• 2016

In this paper, we present a three-dimensional (3-D) automatic target recognition system based on optical integral imaging reconstruction. In integral imaging, elemental images of the reference and target 3-D objects are obtained through a lenslet array or a camera array. Then, reconstructed 3-D images at various reconstruction depths can be optically generated on the output plane by back-projecting these elemental images onto a display panel. 3-D automatic target recognition can be implemented using computational integral imaging reconstruction and digital nonlinear correlation filters. However, these methods require non-trivial computation time for reconstruction and recognition. Instead, we implement 3-D automatic target recognition using optical cross-correlation between the reconstructed 3-D reference and target images at the same reconstruction depth. Our method depends on an all-optical structure to realize a real-time 3-D automatic target recognition system. In addition, we use a nonlinear correlation filter to improve recognition performance. To prove our proposed method, we carry out the optical experiments and report recognition results.

• 한국해양공학회지
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• 제30권3호
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• pp.227-233
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• 2016

This paper presents an underwater structure 3D reconstruction method using a 2D multibeam imaging sonar. Compared with other underwater environmental recognition sensors, the 2D multibeam imaging sonar offers high resolution images in water with a high turbidity level by showing the reflection intensity data in real-time. With such advantages, almost all underwater applications, including ROVs, have applied this 2D multibeam imaging sonar. However, the elevation data are missing in sonar images, which causes difficulties with correctly understanding the underwater topography. To solve this problem, this paper concentrates on the physical relationship between the sonar image and the scene topography to find the elevation information. First, the modeling of the sonar reflection intensity data is studied using the distances and angles of the sonar beams and underwater objects. Second, the elevation data are determined based on parameters like the reflection intensity and shadow length. Then, the elevation information is applied to the 3D underwater reconstruction. This paper evaluates the presented real-time 3D reconstruction method using real underwater environments. Experimental results are shown to appraise the performance of the method. Additionally, with the utilization of ROVs, the contour and texture image mapping results from the obtained 3D reconstruction results are presented as applications.

• 한국측량학회지
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• 제33권6호
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• pp.557-567
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• 2015

With the increasing demands of 3D spatial information in urban environment, the importance of point clouds generation techniques have been increased. In particular, for as-built BIM, the point clouds with the high accuracy and density is required to describe the detail information of building components. Since the terrestrial LiDAR has high performance in terms of accuracy and point density, it has been widely used for as-built 3D modelling. However, the high cost of devices is obstacle for general uses, and the image-based 3D reconstruction technique is being a new attraction as an alternative solution. This paper compares the image-based 3D reconstruction technique and the terrestrial LiDAR in point of establishing the as-built BIM of outdoor structures. The point clouds generated from the image-based 3D reconstruction technique could roughly present the 3D shape of a building, but could not precisely express detail information, such as windows, doors and a roof of building. There were 13.2~28.9 cm of RMSE between the terrestrial LiDAR scanning data and the point clouds, which generated from smartphone and DSLR camera images. In conclusion, the results demonstrate that the image-based 3D reconstruction can be used in drawing building footprint and wireframe, and the terrestrial LiDAR is suitable for detail 3D outdoor modeling.

• 정보처리학회논문지B
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• 제11B권2호
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• pp.133-140
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• 2004

최근 치과 분야의 정보화는 환자자료와 진단영상의 취득과 관리 등을 포함하는 통합 정보화시스템으로써 급속히 발전되었다. 이러한 시스템이 성공하기 위해선 의사가 정확하게 질환을 진단하고 치료하도록 양질의 정보를 제공하며 환자들에게 필요한 고가의 치료를 효과적으로 설득할 수 있는 기능이 확보되어야 한다. 이러한 측면에서 치과분야 시뮬레이션이 가능한 3차원 재구성된 치아모델이 필요하다 치과분야의 치아조작은 대부분 개별 치아 단위로 이루어진다. 따라서 3차원 치아 재구성 시스템은 개변치아의 영역분할과 치아에 맞는 재구성기술이 요구된다. 본 논문에서 적응 최적 임계화를 사용한 치아단위 영역분할 방안과 분할된 경계를 사용한 윤곽선 기반방식의 치아 재구성방안을 제안한다. 즉, 연속된 CT영상에서 개별치아 영역을 정확히 분할하기 위해 슬라이스마다 적응적으로 결정된 최적의 임계치를 사용하여 각 치아를 인접한 이웃 치아와 치조골로부터 분리한다. 분할결과는 3차원 재구성되어 개별 치아를 조작하는 사용자의 입력에 따라 3차원 공간상에서 치아의 이동, 발거 동작을 바탕으로 치과 진료의 시뮬레이션을 가능하게 한다.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.2043-2050
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• 2014

X-선 탐지장치는 검색 대상물에 대한 단면 정보만을 제공하기 때문에 내용물에 대한 판정의 한계가 있다. 스테레오 X-선 탐지 장치는 검색 대상체에 대한 단면 정보와 논문에서 제안된 볼륨기반의 3차원 형상복원 알고리즘을 통해 3차원 정보를 제공하여 검색효율을 높일 수 있다. 또한, 고속 검색을 위해 자동화 검색에 대한 식별자로 형상복원 결과를 적용하고자 유사한 모형의 15개 샘플에 대한 형상 복원 및 검출율을 분석하였다. 검색대상 모델에 대한 복원 결과는 실측 모델과 비교할 때 각각 폭 (2.56%), 높이 (6.15 %)와 깊이 (7.12 %)의 오차를 보이며 높은 정확도를 나타내었다. 또한 K-Mean 클러스터링 알고리즘을 적용하여 실험한 결과 97 %의 검출 효율이 보였다. 본 논문의 결과는 자동화 시스템을 위한 새로운 검색식별자를 제시하며 추가연구를 통해 검색 시스템의 효율성 향상을 위한 연구를 진행할 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1749-1752
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• 2005

For online high accurate reconstruction of an object from an visual information, a linear reconstruction method for multiple images is popular. Basically this method needs many cameras or many different screen shots from different view points. This method, however, has the benefit of less calculation and is adequate for a real time application by comparing other popular method. In this paper, online reconstruction system using more than three cameras is treated. An evaluation method of cameras' position, and of the number is derived for the linear reconstruction method. To decrease errors that are caused from skew of lens, positional error between corresponding points is taken into consideration on the evaluation. The proposed evaluation method enables estimation of the adequate number of cameras and then of feasible view locations. Additionally, repeating search of epipolar lines enables estimation of the hidden point. Comparing with result of an average error analysis, it was confirmed that the proposed methods works effectively.