• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.673-676
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• 2006

본 논문은 산업현장의 불균등한 조명 조건에서 정확한 카메라 교정을 수행할 수 있는 방법을 제안한다. 비접촉 계측을 위한 카메라 교정법은 패턴에서 교정점들을 정확하게 추출할 수 있어야 하며, 평면 패턴을 사용하는 교정 방법은 최소 7개의 교정점을 알아야 한다. 그러나 비접촉 치수 계측기가 설치된 산업현장에서 카메라 교정에 알맞은 조명을 기대하기 힘들다. 본 논문에서는 최적조명제어가 어려운 산업현장에서 치수계측을 위한 카메라 교정을 효과적으로 수행할 수 있는 반자동 카메라 교정방법을 제안한다. 교정패턴상의 최소 4점을 사용자가 지정함에 의해, 조명제어의 어려움으로 인해 교정점 추출이 실패한 교정패턴의 불완전 교정점을 사용하여 이상적인 조명상태에서의 교정점 정보를 예측하고, 이 정보로부터 다시 정확한 교정인자들을 반복적으로 추출하는 방법을 적용한다. 제시된 방법은 렌즈의 투사왜곡에 의한 교정패턴에서도 성공적으로 적용될 수 있음을 실험을 통해 확인하였다.

• Journal of the Korea Convergence Society
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• v.9 no.6
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• pp.203-207
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• 2018

This paper deals with the design and development of a lens system capable of imaging an infrared image of $3{\sim}5{\mu}m$ wavelength bands with a focal length of 24mm and good atmospheric transmission characteristics. The design used CodeV, a commercial design program, and the optimization is carried out with weighting to eliminate chromatic aberration, spherical aberration and distortion. The designed lens system consists of two lenses consisting of Si and Ge. Each lens has an aspherical surface on one side. And this optical system has the resolution of the characteristics that the MTF value is 0.40 at the line width of 29lp/mm and the MTF value is 0.25 at the line width of 20lp/mm. This optical system is considered to have the capability to be applied to the thermal imaging camera for MWIR using the $206{\times}156$ array infrared detector of $25{\mu}m$ pixels and the $320{\times}240$ array infrared detector of $17{\mu}m$ pixels.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.117-126
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• 2008

In this paper, it is presented a digital image processing method and the program (Visual C++) to determine the shape of the suspension bridge. To investigate the precision of this method, a suspension bridge is divided into 5, 13 and 19 images, respectively, by using the 6.3M pixels digital camera with 300mm zoom lens. Obtained results of the Kwang-Ahn Grand Bridge by using this method are fairly close to the real precision surveyed data. The accuracy is more improved by increasing the number of divided images of the structure. The total cost, man power and time of field survey by this method presented in this study could be much more reduced and the developed program could be applied with little modification for other structures like cable-stayed bridges, if lens compensation algorithms and program access capabilities are improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.408-414
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• 2010

When we are collecting traffic information on CCTV images, we have to install the detect zone in the image area during pan-tilt system is on duty. An automation of detect zone with pan-tilt system is not easy because of machine error. So the fisheye lens attached camera or convex mirror camera is needed for getting wide area images. In this situation some troubles are happened, that is a decreased system speed or image distortion. This distortion is caused by occlusion of angled ray as like trembled snapshot in digital camera. In this paper, we propose two methods of de-blurring to overcome distortion, the one is image segmentation by nonlinear diffusion equation and the other is deformation for some segmented area. As the results of doing de-blurring methods, the de-blurring image has 15 decibel increased PSNR and the detection rate of collecting traffic information is more than 5% increasing than in distorted images.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.449-452
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• 2012

본 논문에서는 인간이 환경에 대한 상황을 직접적으로 파악할 수 있는 시각 정보를 제공하기 위해 다중 카메라를 이용한 사용자 시각기반 어라운드 뷰를 개발하였다. 4대의 하향식 경사 카메라를 통하여 영상을 획득하고 켈리브레이션한다. 렌즈의 왜곡을 보정하고 호모그라피 행렬을 계산하여 지표면과 수평이 되는 관점으로 영상을 변환한다. 그 결과 사용자에게 종합적 상황정보 획득이 용이하도록 정보화하기 위한 위성 영상 관점의 정보를 획득할 수 있다. 그리고 4대의 카메라를 동시에 사용하기 위한 하드웨어적 한계를 극복하고자 영상처리가 가능한 임베디드 카메라 모듈을 개발하였다. 사용자-로봇 상호작용을 위해 버튼 및 조이스틱과 같은 기계적 입력장치를 사용하지 않고 사용자의 자연스러운 제스처를 통하여 제어 명령을 입력할 수 있는 터치 패드를 사용하여 사용자 인터페이스를 구축하였다. 개발한 시스템은 시 공간적 한계를 극복하고 원격에서 로봇의 상황정보를 획득하여 사용자 친화적인 로봇제어를 할 수 있다. 위의 내용들을 검증하기 위하여 같은 상황 환경에서의 기존의 시스템과 비교 실험을 진행하였고 실험 결과를 통하여 제안한 시스템의 효용성을 검증하였다.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.63-71
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• 2021

Recently, high-resolution cameras in smartphones enable measurement of minute objects such as cracks in concrete using image processing techniques. The technology to investigate the crack width using an application at an adjacent distance of the close shot range has already been implemented, but the use is limited, so it is necessary to verify the usability of the high-resolution smartphone camera to measure cracks at a longer distance. This study focuses on recognizing the size of subdivided crack widths at a thickness within 1.0 mm of crack width at a distance of 2 m. In recent Android-based smartphones, an experiment was conducted focusing on the relationship between the unit pixel size, which is a measurement component, and the shooting distance, depending on the camera resolution. As a result, it was possible to confirm the necessity of a smartphone lens for the classification and quantification of microcrack widths of 0.3 mm to 1mm. The universal telecentric lens for smartphones needed to be installed in an accurate position to minimize the effect of distortion. In addition, as a result of applying a 64 MP high-resolution smartphone camera and double magnification lens, the crack width could be calculated within 2 m in pixel units, and crack widths of 0.3, 0.5, and 1mm could be distinguished.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.177-180
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• 2009

볼록거울을 사용하여 CCTV시스템을 만들면 카메라 수를 줄이는 효과가 있다. 이 경우 볼록거울 영상은 휜 영상이므로 평면영상처럼 변환해야 한다. 이 경우에, 중앙에 비추인 영상은 평면 영상으로 변환 후에도 왜곡이 거의 없지만 거울의 테두리 부근에서 얻은 영상을 변환하면 왜곡이 심하게 나타나서 영상 내의 물체를 식별하기가 어려워진다. 렌즈의 초점이 거울의 중심부에 맞춰져 있기 때문에 변에 있는 영상은 픽셀들 사이에 겹침이 일어나기 때문이다. 본 논문에서는 픽셀들 사이의 광학적 겹침을 극복하기 위해 확산 방정식의 후진대입 해를 사용하였다. 결과를 분석하기 위해 PSNR값을 조사하였더니 제안된 방법은 N. Moayeri의 방법보다 4 dB 정도 개선되었다.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.111-121
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• 2018

RIn this research, digital elevation models, true-ortho image and 3-dimensional digital complied data was generated and evaluated using unmanned aircraft vehicle stereoscopic images by applying photogrammetric principles. In order to implement stereoscopic vision, digital Photogrammetric Workstation should be used necessarily. For conducting this, in this study GEOMAPPER 1.0 is used. That was developed by the Ministry of Trade, Industry and Energy. To realize stereoscopic vision using two overlapping images of the unmanned aerial vehicle, the interior and exterior orientation parameters should be calculated. Especially lens distortion of non-metric camera must be accurately compensated for stereoscope. In this work. photogrammetric orientation process was conducted using commercial Software, PhotoScan 1.4. Fixed wing KRobotics KD-2 was used for the acquisition of UAV images. True-ortho photo was generated and digital topographic map was partially produced. Finally, we presented error analysis on the generated digital complied map. As the results, it is confirmed that the production of digital terrain map with a scale 1:2,500~1:3,000 is available using stereoscope method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.816-819
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• 2005

This paper proposes a coordinate correction technique using the transformation of 3D parabolic coordinate function and BP(Back Propagation) neural network in order to solve space distortion problem caused by using catadioptric camera. Although Catadioptric camera can obtain omni-directional image at all directions of 360 degrees, it makes an image distorted because of an external form of lens itself. Accordingly, To obtain transformed ideal distance coordinate information from distorted image on 3 dimensional space, we use coordinate transformation function that uses coordinates of a focus at mirror in the shape of parabolic plane and another one which projected into the shape of parabolic from input image. An error of this course is modified by BP neural network algorithm.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.149-160
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• 2014

Recently studies on application development and utilization using sensors and devices embedded in smartphones have flourished at home and abroad. This study aimed to analyze the accuracy of the images of smartphone to determine three-dimension position of close objects prior to the development of photogrammetric system applying smartphone and evaluate the feasibility to use. First of all, camera calibration was conducted on autofocus and infinite focus. Regarding camera calibration distortion model with balance system and unbalance system was used for the decision of lens distortion coefficient, the results of calibration on 16 types of projects showed that all cases were in RMS error by less than 1 mm from bundle adjustment. Also in terms of autofocus and infinite focus on S and S2 model, the pattern of distorted curve was almost the same, so it could be judged that change in distortion pattern according to focus mode is very little. The result comparison according to autofocus and infinite focus and the result comparison according to a software used for multi-image processing showed that all cases were in standard deviation less than ${\pm}3$ mm. It is judged that there is little result difference between focus mode and determination of three-dimension position by distortion model. Lastly the checkpoint performance by total station was fixed as most probable value and the checkpoint performance determined by each project was fixed as observed value to calculate statistics on residual of individual methods. The result showed that all projects had relatively large errors in the direction of Y, the direction of object distance compared to the direction of X and Z. Like above, in terms of accuracy for determination of three-dimension position for a close object, the feasibility to use smartphone camera would be enough.