• Imaging Science in Dentistry
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• 제48권2호
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• pp.111-119
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• 2018

Purpose: This study was conducted to evaluate the accuracy of linear measurements of 3-dimensional (3D) images generated by cone-beam computed tomography (CBCT) and facial scanning systems, and to assess the effect of scanning parameters, such as CBCT exposure settings, on image quality. Materials and Methods: CBCT and facial scanning images of an anthropomorphic phantom showing 13 soft-tissue anatomical landmarks were used in the study. The distances between the anatomical landmarks on the phantom were measured to obtain a reference for evaluating the accuracy of the 3D facial soft-tissue images. The distances between the 3D image landmarks were measured using a 3D distance measurement tool. The effect of scanning parameters on CBCT image quality was evaluated by visually comparing images acquired under different exposure conditions, but at a constant threshold. Results: Comparison of the repeated direct phantom and image-based measurements revealed good reproducibility. There were no significant differences between the direct phantom and image-based measurements of the CBCT surface volume-rendered images. Five of the 15 measurements of the 3D facial scans were found to be significantly different from their corresponding direct phantom measurements(P<.05). The quality of the CBCT surface volume-rendered images acquired at a constant threshold varied across different exposure conditions. Conclusion: These results proved that existing 3D imaging techniques were satisfactorily accurate for clinical applications, and that optimizing the variables that affected image quality, such as the exposure parameters, was critical for image acquisition.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.16-21
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• 2008

The demand for three-dimensional (3D) shape measurements is increasing in a variety of fields, including the manufacture of molds and dies. The most popular technology for 3D shape measurement is the coordinate measuring machine (CMM) with a contact trigger probe. Although a CMM provides a high degree of accuracy, it is inefficient due to its long measuring time. It also has difficulty measuring soft objects that can be deformed by the touch of the contact probe. In addition, a CMM cannot digitize areas that are difficult to reach, and cannot capture very minute details on the surface of complex parts. For these reasons, optical non-contact measurement techniques are receiving more attention since they eliminate most of the problems associated with contact methods. Laser scanning is emerging as one of the more promising non-contact measurement techniques. This paper describes various acquisition considerations for laser scanning, including the accuracy of the 3D scan data, which depends on the charge-coupled device (CCD) gain and noise. The CCD gain and noise of a 3D laser scanner are varied while keeping the other conditions constant, and the measurement results are compared to the dimensions of a standard model. The experimental results show that a considerable time savings and an optimum degree of accuracy are possible by selecting the proper CCD gain and noise.

• Journal of the Optical Society of Korea
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• 제16권1호
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• pp.42-46
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• 2012

We have developed a fluorescence optical detection system using a digital micromirror device (DMD) for monitoring 3D cell culture matrices in situ. Full 3D imaging with fast scanning speed was implemented by the combined action of a DMD and a motorized stage. Imaging results with fluorescent microbeads measure the minimum axial resolution of the system as $6.3{\mu}m$, while full 1-mm scanning through 3D alginate-based matrix was demonstrated. For cell imaging, improved images were obtained by removing background fluorescence although the scanning distance was reduced because of low intracellular fluorescence efficiency. The system is expected to be useful to study various dynamics and behaviors of 3-dimensionally cultured cells in microfluidic systems.

• International Journal of Contents
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• 제5권3호
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• pp.19-23
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• 2009

Laser scanning technology is a maturing measurement technology which is capable of obtaining 3D measurement data of objects with high-accuracy, high-resolution and in a short time. Laser scanners are used more and more as surveying instruments for various applications. This paper describes the procedure of 3D data acquirement using terrestrial LiDAR and section drawing extraction through a series of processing for remodeling the interior of a department building. Accurate drawings are needed for improvement construction of building interior. However if the design drawings of that time of construction work were lost or damaged or actual dimensions of drawings differ from those of design drawings, the interior should be resurveyed. In this study, the extraction process of interior plane figures were suggested through using laser scanning and related reverse engineering software

• 한국생활과학회지
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• 제21권3호
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• pp.539-550
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• 2012

In-depth knowledge of fabric microstructure is essential for understanding clothing comfort since it plays a significant role in heat and mass transfer between the human body and clothing. In this study, a novel method was employed for investigating 3D surfaces and solid construction characteristics of specific fabrics by using a reverse engineering technique. The surface construction data were obtained by a confocal laser scanning microscope and then manipulated by a 3D analysis program. Triangle mesh was used for connecting each 3D point, with clouds and fabric surface characteristics created by rendering techniques. For generating a 3D solid model, determinants of radius of curvature was used. According to the proposed method, actual surface expression of the real fabric was achieved successfully. The results from this methodology can be applied to the detailed analysis of clothing comfort that is highly influenced by the microstructure of the fabric.

• 대한공간정보학회지
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• 제16권2호
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• pp.41-47
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• 2008

지도 제작이 갖는 의미는 그 나라의 측량 기술 수준을 대변한다는 것이다. 또 그 나라 사람들이 얼마만큼 세계속에서 국제적 활동을 하고 있는지에 대한 묵시적 표현 수단이라고 불 수 있다. 현재 우리나라에서는 국가 기본도를 비롯하여 여러 축척의 수치지도가 제작되어있다. 그러나 현재의 수치지도는 항공사진측량 또는 위성영상을 이용하여 신규제작이나 수정 갱신이 이루어지고 있지만, 산업의 발달과 국가경제 성장으로 인하여 수시로 변화하는 지형 지물에 대한 즉각적인 수정이나 갱신을 실시하기에는 많은 어려움이 있다. 따라서 본 연구에서는 3차원 레이저 스캐닝(3D Laser Scanning)을 국부지역에 적용하여 실제 지형과 같은 3차원 공간좌표로 취득하여 수치지도 수정 갱신에 요구하는 측위 정확도 제시와 실험에 적용하여 사용자 편의를 제공하고자 한다.

• 한국전자통신학회논문지
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• 제9권1호
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• pp.25-32
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• 2014

암각화는 문자가 있기전에 선사시대의 공동체를 이해하는데 핵심적인 역할을 하기 때문에 전 세계적으로 매우 중요한 문화유산이다. 요즘 3D 데이터는 미래세대에게 물려줄 수 있는 중요한 문화유산의 모양을 영구 기록하는데 필수적인 요소이다. 최근의 3D스캐닝 기술은 매우 사실적인 3D 모델생성이 가능하기 때문에 체험자를 3D세계로 끌어드릴수 있는 가상현실 박물관 전시에 활용될 수 있다. 본 연구에서는 새로운 동작인식 방법에 기반한 3D암각화 VR(Virtual Reality) 콘텐츠를 구현하였다. 제안된 동작인식방법은 3차원 깊이센서를 이용하여 얻어진 체험자의 움직임을 정의된 동작과 비교함으로써 동작을 인식한다. 또한 정밀하고 비파괴적인 수단으로서 3D스캐닝 기술을 이용하여 3D 암각화 데이터를 기록하기 위한 새로운 접근방법을 제안한다.

• 대한공간정보학회지
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• 제24권2호
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• pp.79-87
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• 2016

As 3D geospatial information is demanded, terrestrial laser scanners which can obtain 3D model of objects have been applied in various fields such as Building Information Modeling (BIM), structural analysis, and disaster management. To acquire precise data, performance evaluation of a terrestrial laser scanner must be conducted. While existing 3D surveying equipment like a total station has a standard method for performance evaluation, a terrestrial laser scanner evaluation technique for users is not established. This paper categorizes and analyzes error sources which generally occur in terrestrial laser scanning. In addition to the prior researches about categorizing error sources of terrestrial Laser scanning, this paper evaluates the error sources by the actual field tests for the smooth in-situ applications.The error factors in terrestrial laser scanning are categorized into interior error caused by mechanical errors in a terrestrial laser scanner and exterior errors affected by scanning geometry and target property. Each error sources were evaluated by simulation and actual experiments. The 3D coordinates of observed target can be distortedby the biases in distance and rotation measurement in scanning system. In particular, the exterior factors caused significant geometric errors in observed point cloud. The noise points can be generated by steep incidence angle, mixed-pixel and crosstalk. In using terrestrial laser scanner, elaborate scanning plan and proper post processing are required to obtain valid and accurate 3D spatial information.

• 한국측량학회지
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• 제26권6호
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• pp.561-569
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• 2008

현재, 3D 영상모형을 구축하기 위하여 위성영상, 항공영상 및 항공레이저 측량데이터가 주로 이용되고 있으나, 상기 데이터만을 이용하여 구축된 모형은 지형과 지물을 세밀하고 사실감 있게 표현하는데 제한적이기 때문에 고품질의 영상모형 구축이 필요한 실정이다. 3D 영상모형 구축시 3D 모형을 제작하고, 지상사진으로부터 텍스쳐를 제작하여 3D 모형에 사실감을 부여한다. 본 연구에서는 지형과 인공 시설물을 대상으로 사진측량 및 레이저측량 데이터를 이용하여 공간정확도, 세밀묘사 및 현실감이 강조된 실세계에 근접한 3D 영상모형을 구축하기 위한 기법을 분석하였다. 연구결과 위치정확도와 함께 사진과 같은 사실감을 확보한 3D 영상모형을 구축하였고 인터넷 3D 영상지도 서비스를 통하여 제공 할 수 있도록 하였다. 3D 영상모형을 이용하여 일조권분석, 경관분석, 시설물관리 등 다양한 분야에 활용할 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.899-902
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• 2006

For a quick and accurate 3D modelling of a building, laser scanning data, digital maps, aerial photographs and satellite images should be fusioned. Moreover, library establishment according to a standard structure of a building and effective texturing method are required in order to determine the structure of a building. In this study, we made a standard library by categorizing Korean village forms and presented a model that can predict a structure of a building from a shape of the roof on an aerial photo image. We made an ortho image using the high-definition digital image and considerable amount of ground scanning point cloud and mapped this image. These methods enabled a more quick and accurate building modelling.