• The KIPS Transactions:PartB
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• v.12B no.5 s.101
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• pp.567-576
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• 2005

This paper proposes an image-based modeling method which recovers 3D models using projected line segments in multiple images. Using the method, a user obtains accurate 3D model data via several steps of simple manual works. The embedded nonlinear minimization technique in the model parameter estimation stage is based on the distances between the user provided image line segments and the projected line segments of primitives. We define an error using a finite line segment and thus increase accuracy in the model parameter estimation. The error is defined as the sum of differences between the observed image line segments provided by the user and the predicted image line segments which are computed using the current model parameters and camera parameters. The method is robust in a sense that it recovers 3D structures even from partially occluded objects and it does not be seriously affected by small measurement errors in the reconstruction process. This paper also describesexperimental results from real images and difficulties and tricks that are found while implementing the image-based modeler.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.59-63
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• 2014

This paper describes the basic principles of 3D broadcast system and proposes new 3D broadcast technology that reduces the amount of data by applying CS(Compressed Sensing). Differences between Sampling theory and the CS technology concept were described. Recently proposed CS algorithm AMP(Approximate Message Passing) and CoSaMP(Compressive Sampling Matched Pursuit) were described. This paper compared an accuracy between two algorithms and a calculation time that image data compressed and restored by these algorithms. As result determines a low complexity algorithm for 3D broadcast system.

• Journal of the Korea Computer Graphics Society
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• v.24 no.3
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• pp.61-71
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• 2018

When triangular meshes are generated from the point clouds in global space reconstructed through camera pose estimation against captured RGB-D streams, the quality of the resulting meshes improves as more triangles are hired. However, for 3D reconstructed models beyond some size threshold, they become to suffer from the ugly-looking artefacts due to the insufficient precision of RGB-D sensors as well as significant burdens in memory requirement and rendering cost. In this paper, for the generation of 3D models appropriate for real-time applications, we propose an effective technique that extracts high-quality textures for moderate-sized meshes from the captured colors associated with the reconstructed point sets. In particular, we show that via a simple method based on the mapping between the 3D global space resulting from the camera pose estimation and the 2D texture space, textures can be generated effectively for the 3D models reconstructed from captured RGB-D image streams.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.325-326
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• 2023

본 논문은 2차원적인 이미지를 모델링 하여, 대한민국의 보물 제750호이자 오래된 거돈사지 삼층석탑의 복원과 구현을 위한 연구이다. 기존 2D 이미지를 벗어나 문화재의 특성상 3D 형태의 복원이 적합하여 연구를 진행하였다. 문화재 복원은 자료와 전문가의 기술 및 역사적인 기록물 자료에 의존해 복구한다. 최근 인공지능 및 기술의 발달로 문화재 정보를 바탕으로 한 3차원 기술을 사용하여 다양한 데이터들과 프로그램을 이용한 모델링이 가능하다. 본 연구는 거돈사지 삼층석탑의 복원이 실제적이고도 구체적인 다각도의 방향에서 더 정밀하고 정확하게 도출하는데 기여할 것으로 기대된다.

• Conservation Science in Museum
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• v.27
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• pp.1-22
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• 2022

A chimi(a roof ridge decoration) excavated from the Busosan Temple Site in Buyeo was restored in 1978 at the Buyeo Museum. The gypsum restoration material had deteriorated over time and part of it was seriously damaged and unable to bear the weight of the chimi. The chimi features traces of emergency treatment revealing that the inside of the body and some portions of the tail were reinforced several times using epoxy resin. A condition survey performed in preparation for its transfer for an exhibition found the lower body and wings of the chimi to be highly vulnerable and it was determined that the chimi needed further restoration. The dismantling of the chimi for restoration revealed several elements that provide clues to the production techniques applied by its makers, so they were subjected to inspection. This study explores the production techniques used in the chimi from the Busosan Temple Site that were revealed during the process of dismantling it for restoration. The chimi was inspected using 3D scanning and its rigid vertical shape was restored to a natural form based on the production techniques identified during the dismantling process. The existing restoration material was replaced to improve durability. 3D printed elements were produced based on 3D modelling and were joined to the original chimi to correct its shape and fill in the missing parts, restoring the chimi to its original appearance.

• Electronics and Telecommunications Trends
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• v.22 no.4 s.106
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• pp.1-11
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• 2007

3차원 복원 기술은 실세계에 존재하는 물체의 3차원 형상과 표면의 색상을 디지털화하는 기술이다. 일반적으로 가상현실, 게임, 애니메이션 등의 컴퓨터 그래픽스에 기반한 응용에서는 숙련된 디자이너가 수작업으로 3차원 모델을 제작하는데, 이는 시간이 많이 소요되고, 디자이너의 숙련도에 따라서 품질의 차이가 많은 단점이 있다. 뿐만 아니라 실세계에 존재하는 물체를 모델링할 때는 일일이 측정을 하는 과정을 거쳐야 하는 단점이 있다. 3차원 복원 기술은 이에 대한 대안으로 연구되고 있는 기술로써, 이미 많은 응용 분야에서 활용되고 있을 뿐만 아니라 새로운 서비스가 꾸준히 창출되고 있는 기술이다. 본 고에서는 3차원 복원 기술을 분류하고, 컴퓨터 비전 분야의 주연구 대상인 영상분석을 통한 3차원 복원 기술에 대해 설명한다. 또한, 3차원 복원 기술의 응용 사례와 상용화된 제품에 대해 설명하고, 향후 발전 방향을 제시한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.116-122
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• 2016

This paper proposes a practical object shape reconstruction method using an underwater imaging sonar. In order to reconstruct the object shape, three methods are utilized. Firstly, the vertical field of view of imaging sonar is modified to narrow angle to reduce an uncertainty of estimated 3D position. The wide vertical field of view makes the incorrect estimation result about the 3D position of the underwater object. Secondly, simple noise filtering and range detection methods are designed to extract a distance from the sonar image. Lastly, a low pass filter is adopted to estimate a probability of voxel occupancy. To demonstrate the proposed methods, object shape reconstruction for three sample objects was performed in a basin and results are explained.

• Journal of Conservation Science
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• v.25 no.2
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• pp.115-130
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• 2009

This study was focused on digital restoration and structural stability evaluation applying 3D scanning system of five-storied Magoksa temple stone pagoda in Gongju. For these, the digital restoration of the pagoda was completed using laser scan data which is measured 16 directions and data processing program of 7 stages. As a result of digital restoration, the overall height and width of stone properties showed a little difference in directions and the width of roof stones appeared very high difference of each floor. The width of pagoda body become smaller to the fifth floor, but gradual decrease rate showed irregular characteristics. Also, as result of 3D image analysis for structural stability evaluation, the displacement occurred toward northwest in second body stone to upper final stone except for central axis of the first body stone which inclines toward southwest. Such 3D image analysis is required quantification of survey method and should be applied to various field such as quantitative damage maps in order to utilize a conservation of stone cultural heritages, continuously.

• Korean Journal of Heritage: History & Science
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• v.44 no.2
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• pp.76-95
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• 2011

After dismantled, Mireuksajiseoktap(Stone pagoda of Mireuksa Templesite) is being in the stage of restoration design. Now, different ways - producing restoration model, a 3 dimension simulation - have been requested to make more detailed and clearer restoration design prior to confirmation of its restoration design and actual restoration carry-out. This thesis proposes the way to build the detailed model for better restoration plan using extensively-used Reverse Engineering technique and Rapid Prototyping. It also introduces each stage such as a 3-dimension actual measurement, building database, a 3-dimension simulation etc., to build a desirable model. On the top of that, this thesis reveals that after dismantled, MIruksaji stone pagoda's interior and exterior were not constructed into pieces but wholeness, so that its looks can be grasped in more virtually and clearly. Secondly, this thesis makes a 3-dimension study on the 2-dimension design possible by acquiring basic materials about a 3-dimension design. Thirdly, the individual feature of each member like the change of member location can be comprehended, considering comparing analysis and joint condition of member. Lastly, in the structural perspective this thesis can be used as reference materials for structure reinforcement design by grasping destructed aspects of stone pagoda and weak points of the structure. In dismantlement-repair and restoration work of cultural properties that require delicate attention and exactness, there may be evitable errors on time and space in building reinforcement and restoration design based on a 2-dimension plan. Especially, the more complicate and bigger the subject is, the more difficult an analysis about the status quo and its delicate design are. A series of pre-review, based on the 3-dimension data according to actual measurement, can be one of the effective way to minimize the possibility that errors about time - space happen by building more delicate plan and resolving difficulties.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.303-315
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• 2007

This paper proposes a 3D structure recovery and registration method that uses four or more common points. For each frame of a given video, a partial structure is recovered using tracked points. The 3D coordinates, camera positions and camera directions are computed at once by our improved scaled orthographic factorization method. The partially recovered point sets are parts of a whole model. A registration of point sets makes the complete shape. The recovered subsets are integrated by transforming each coordinate system of the local point subset into a common basis coordinate system. The process of shape recovery and integration is performed uniformly and linearly without any nonlinear iterative process and without loss of accuracy. The execution time for the integration is significantly reduced relative to the conventional ICP method. Due to the fast recovery and registration framework, our shape recovery scheme is applicable to various interactive video applications. The processing time per frame is under 0.01 seconds in most cases and the integration error is under 0.1mm on average.