• 한국HCI학회:학술대회논문집
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• 2007.02c
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• pp.170-175
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• 2007

영상 재투영이란, 깊이 맵을 투영하여 임의의 시점에서 본 이미지를 생성해내는 기법을 말한다. 기존의 CPU를 이용한 영상 재투영 기법들의 가장 큰 단점은 CPU와 GPU 간의 데이터 복사가 일어나고 재투영 연산 자체의 속도가 느리기 때문에 실시간 렌더링이 불가능 하다는 것이다. 따라서 본 논문에서는 GPU를 이용하여 영상 재투영을 구현하고 실시간에 이미지를 렌더링하는 기법을 소개한다. 우리의 기법은 입력으로 참조 이미지와 해당 이미지의 깊이 맵이 주어졌을 때, 임의의 시점에서 보이는 새로운 이미지를 실시간으로 생성한다. 임의의 시점에서 이미지를 생성하기 위해, 각 픽셀에서 참조 이미지에 해당하는 평면을 렌더링하여 시점 반대 방향의 광선을 생성한다. 이 광선을 참조 이미지의 투영 공간으로 변환한 후, 광선과 깊이 맵간의 교차점을 찾는다. 이렇게 찾아낸 깊이 맵의 교차점과 일치하는 참조 이미지의 픽셀 색으로 새로운 시점의 이미지를 만들어 낼 수 있다. 이와 같은 기법은 기하 정보의 복잡도와 관계없이 수십 프레임의 속도로 실시간 렌더링이 가능하다.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.81-88
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• 2007

The geometry of satellite image captured by linear CCD sensor is different from that of frame camera image. The fact that the exterior orientation parameters for satellite image with linear CCD sensor varies from scan line by scan line, causes the difference of image geometry between frame and linear CCD sensor. Therefore, we need the epipolar geometry for linear CCD image which differs from that of frame camera image. In this paper, we proposed a method of resampling linear CCD satellite image in epipolar geometry under the assumption that image is not formed in perspective projection but in parallel projection, and the sensor model is a 2D affine sensor model based on parallel projection. For the experiment, IKONOS stereo images, which are high resolution linear CCD images, were used and tested. As results, the spatial accuracy of 2D affine sensor model is investigated and the accuracy of epipolar resampled image with RFM was presented.

• Journal of Korea Game Society
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• v.10 no.4
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• pp.3-13
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• 2010

This study is about projection methods in computer games that support graphic user interface. Most of previous studies were case studies on or aesthetic approaches to a specific projection method. We investigated projection methods observed in computer games according to the chronicle of games, and studied changes in the methods and their future direction. Furthermore, we examined the emotional and productive aspects of various projection methods, and found that projection methods in computer games are being developed in accordance with graphic designers' job difficulty and computer processing capacity. Project, which determines contents consumers' view, is a very important factor to be decided at the planning stage of contents development. In this sense, we expect the results of this study to make a contribution to relevant areas.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.403-408
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• 2015

Hard X-ray has been widely used in medical and industrial fields because it can be applied to observe the inside of a sample. Computed tomography provides sectional images of the sample through the reconstruction of the projection images. The quality of sectional images strongly depends on that of projection images. Ring artifact appeared on the seconal image can be made by the abnormal pixels of the detector used. In this study, we examine the ring artifact ratio in the circle phantom as a function of detection error of the detector used in computed tomography. The ring artifact increased with the increment of detection error under parallel and fan beam geometries and strongly increased near the center of rotation. The corrections, dead pixel and flat field corrections, for the images taken with the detector are required before the image reconstruction process to reduce the ring artifact in the computed tomography.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.45.3-45.3
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• 2016

2015년 12월에 개관한 국립부산과학관은 동남권 유일의 종합과학관으로 천문교육을 위한 천체관측소와 천체투영관을 보유하고 있다. 천체관측소에는 국내 최대규모의 구경 350mm 굴절망원경을 포함 다양한 천체관측 및 교육장비를 갖추고 있고, 천체투영관에는 디지털식 투영기와 직경 17m의 돔스크린, 133석 규모의 시설을 갖추고 있다. 이러한 천문시설은 일반개인관람, 학교단체교육, 학교 및 가족이 참여하는 1박 2일 캠프프로그램, 천문행사 등에 활용되고 있다. 개관 1주년을 바라보고 있는 시점에서 지속적인 천문 교육수요 창출을 위해 보다 효율적인 운영방법모색 및 다양한 컨텐츠를 개발이 요구되고 있다. 이를 기반으로 2021년 부산에서 개최되는 제31차 국제천문연맹총회(IAUGA)에서의 국립부산과학관의 역할을 증대시키고자 한다. 이번 발표에서는 국립부산과학관의 천문시설의 활용 현황을 소개하고 타 기관의 우수 사례를 공유하여 국립부산과학관 뿐만 아니라 전국 천문교육의 지속적인 발전 방법을 논의하고자 한다.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.85-91
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• 2018

Computed tomography, which obtains section images from reconstruction process using projection images, has been applied to various fields. The spatial resolution of the reconstructed image depends on the device used in CT system, the object, and the reconstruction process. In this paper, we investigates the effect of the number of projection images and the pixel size of the detector on the spatial resolution of the reconstructed image under the parallel beam geometry. The reconstruction program was written in Visual C++, and the matrix size of the reconstructed image was $512{\times}512$. The numerical bar phantom was constructed and the Min-Max method was introduced to evaluate the spatial resolution on the reconstructed image. When the number of projections used in reconstruction process was small, artifact like streak appeared and Min-Max was also low. The Min-Max showed upper saturation when the number of projections is increased. If the pixel size of the detector is reduced to 50% of the pixel size of the reconstructed image, the reconstructed image was perfectly recovered as the original phantom and the Min-Max decreased as increasing the detector pixel size. This study will be useful in determining the detector and the accuracy of rotation stage needed to achieve the spatial resolution required in the CT system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.629-634
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• 2000

This System is developed for the estimation of the Camera Lens Resolution. Signal data proportional to light intensity is obtained and sampled from the 2D CCD. Based on the measured signal. the MTF charateristcs of a camera lens are measured. We could measure the sagittal and tangential MTF in the on and off-axis at the same time. The automatic measurig methods for optimal image plane, magnification, and best marginal direction of test lens are presented.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.78.1-78.1
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• 2011

현재 국내에는 약 30여 개의 종합(관측실과 투영관이 있는) 천문시설이 운영 중에 있으며 매년 2-3개의 시설이 추가로 건설 되고 있다. 대부분의 천문시설에서는 별자리 설명, 천체투영관에서의 영상물 상영, 그리고 천체망원경을 이용한 관측실습 등 한정된 소재와 일관된 형식의 천문교육 프로그램을 운영 하고 있다. 하지만 천문학은 일반 대중들이 많은 흥미와 관심을 가지는 분야이기 때문에 여러 가지 다양한 소재와 형식의 교육프로그램 및 콘텐츠 개발이 필요하다. 특히 최근 언론에 자주 등장하는 UFO, 황도 13궁, 태양 폭발, 우주선(Cosmic Rays)이 지구에 미치는 영향 등의 소재들은 일반인들이 잘못된 개념을 가지기 쉬운 분야이기 때문에 여기에 대한 올바른 과학내용을 일반인들이 이해하기 쉽도록 전달하는 것이 필요하다. 교육 콘텐츠는 디지털 천체투영기를 이용한 스크립트 프로그램 개발, 관측실습 전 후의 이론 교육 등 다양한 형태가 될 수 있다. 각 천문시설 운영자들이 직접 다양한 교육 콘텐츠를 개발하는 데에는 한계가 있으므로 기관협력체나 천문연구원 등의 체계적인 천문교육 콘텐츠 개발 및 보급이 절실하다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.6
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• pp.17-30
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• 1999

This paper proposes a new stereophonic acoustic echo canceller to prevent impairments on the voice quality and to remove acoustic echo effectively appearing in stereo environment at the instant of abrupt change of the transmission room environment in teleconferencing system. In stereophonic acoustic echo canceller, the major defective problems are the large computational complexity of estimating echo path systems due to the long impulse response of the true echo paths and the performance degradation of echo canceller due to large correlation between dual stereo signals. Moreover, the change of the suboptimal solution for the echo canceller was considered as a critical deficient factor on to the performance of stereophonic echo canceller. To overcome these problems, this paper proposes pseudo stereophonic acoustic echo canceller using Hyper-plane projection algorithm, which shows the robustness to the environment change of the transmission room and the efficiency of computational complexity.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.182-188
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• 2002

We have analyzed the phase-calculation-error of a three-dimensional shape measurement system using the projection of phase shifted fringe patterns. In this study, we have dealt various errors; an error caused by the variation of quantization levels, an error caused by the defocus of fringe pattern projected images, an error caused by phase-shifting errors, an error caused by the intensity variation of the background and modulation amplitude of fringe pattern projected images during the projection of multiple patterns, an error caused by the distortion of sinusoidal shape of a fringe pattern. The results will contribute to the design of a three-dimensional shape measurment system and give an important meaning to the calculation and the analysis of the accuracy of a system.