• Journal of Korea Multimedia Society
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• v.14 no.8
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• pp.1082-1093
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• 2011

Traditional rendering of cartoon character cannot revive the feeling of concept drawings properly. In this paper, we propose capture technology to get toon shading model from the concept drawings and with this technique, we provide a new novel system to render 3D cartoon character. Benefits of this system is to cartoonize the 3D character according to saliency to emphasize the form of 3D character and further support the sketch-based user interface for artists to edit shading by post-production. For this, we generate texture automatically by RGB color sorting algorithm to analyze color distribution and rates of selected region. In the cartoon rendering process, we use saliency as a measure to determine visual importance of each area of 3d mesh and we provide a novel cartoon rendering algorithm based on the saliency of 3D mesh. For the fine adjustments of shading style, we propose a user interface that allow the artists to freely add and delete shading to a 3D model. Finally, this paper shows the usefulness of the proposed system through user evaluation.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.437-440
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• 2004

HMS(Hull Mounted Sonar) 운용 시 수중음속구조의 영향에 의한 음파가 경계면(해저면, 해수면)의 반사를 통해서 근거리 음영구역(short range shadow zone)을 발생시킨다(그림 1). 따라서 본 논문에서는 다양한 수중음파탐지 무기체계 가운데 특히 단상태 (monostatic) 조건일 때 HMS에 의해 발생하는 근거리 음영구역을 최소화하는 방안을 연구하였다. 즉, 2차원 수중공간 (수심-거리)에서 빔형성기법 (beamforming)을 이용한 HMS Vertical Scanning (HMS Verscan) 기법을 제안하여 수치 실험을 수행하였다. 수치실험을 위해 HMS 운용환경에 근접한 고주파 음선모델(BELLHOP)과 잔향음 모델(HYREV)을 이용하였다. 그 결과 HMS Verscan 기법은 수평방향의 음파방사에 의해 주로 발생하는 근거리 음영구역으로 해저반사를 통하여 음파를 전달시켰고, 근거리 음영 구역에 숨어있는 표적의 탐지가능성을 높였다. 또한 실제 산란환경을 고려한 수치실험 결과에서도 부분적으로 표적이 탐지가 됨으로써 HMS Verscan 기법의 근거리 음영구역의 감소효과를 확인하였다.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.771-778
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• 2008

A Device performance analyzing method for appropriate level in hybrid rendering model is suggested. In recent research, we proposed a hybrid rendering model which is applying a proper shading method to each of polygons consisting of an object. The number of polygon for Gouraud shading and that for flat shading should be considered according to a current device performance and system environments. Therefore, this paper suggests the method to calculate automatically a proper resolution of a mesh of object and a proper level of mixture between Gouraud and a flat shading, considering a current device performance and a preference of end-user. The rendering model is so simple that it can be an efficient replacement to reduce a real-time rendering time since it provides automatically multi-level of rendering resolution to an executing environments. Moreover, it can be adopted in real-time adaptive service for 3D graphic contents like a graphic game under various device environments.

• Journal of Korea Multimedia Society
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• v.14 no.5
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• pp.691-702
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• 2011

Recently, several researchers have attempted to combine human visual perception and computer graphics. Cole et. al. suggest the study results in which line drawing algorithm in computer graphics characterize the properties of line drawing made by artists. The paper also evaluates CG line drawing algorithms depending on whether people recognize effectively specific 3D shape from the image made by those CG line drawing algorithms. However, human recognizes the shape of objects more effectively in image made by BRDF shading model than line drawing algorithm. It means that the shading factor is important to recognize shape with human perception. In this paper, we analyze the correlation between shading made by human artists and that made by CG shading algorithms. The study is to characterize the mathematical properties of artists' shading and CG shading. This type of analysis can guide the future development of new CG shading algorithm in computer graphics for the purpose of shape perception.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.1
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• pp.37-46
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• 2004

In this paper, we propose an improved reproduction algorithm for a realistic image of the real scene based on the spectral distribution of lights and objects. The proposed method for the realistic image is focused on a more accurate reproduction of an image incident on the sight of the viewer. At first, to reproduce an image accurately incident on a sight of viewer, we used the backward ray tracing method based on spectral distribution of object and illuminant representing its physical characteristic used in real. Next, we propose utilizing the improved shading model of the reproduction algorithm of realistic image by applying Bouguer-Beer's law to consider an optical absorptive property of transparent objects. We also define a new ambient light term which is considered the diffuse reflection of neighboring objects instead of constant ambient light. The simulation results show that the proposed algorithm can reproduce the visually similar image with a scene incident on a sight of viewer.

• Journal of Digital Contents Society
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• v.9 no.3
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• pp.509-516
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• 2008

We propose the Hybrid Rendering model to support multi-resolution for computer graphics. LOD method for computer graphics system considering performance of device environment and end-user preference usually adopts mesh resolution, mipmap in texture rendering, or oct-tree data structure in ray tracing. The hybrid rendering model, as a local shading model combining Gouraud shading model and a flat shading model, applies a proper shading method to each of polygons consisting of an object. This method can be an effective alternative to reduce real-time rendering time so that it can be utilized in real time adaptive service of computer graphic contents among various device environments under ubiquitous environments.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.49-53
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• 2000

본 논문에서는 로그노말 분포된 전파음영 환경에서 통화의 신뢰도를 유지하기 위해 필요한 링크 마진을 경로손실과 전파음영의 감쇠를 포함하는 전파 손실 모델을 사용하여 분석하였다. CDMA 셀룰러 시스템에서 셀 반경이 커지게 되면 요구되는 링크 마진도 증가하게 되어 핸드오프이득은 요구되는 링크 마진만큼 감소하게 된다. 이러한 셀 영역과 링크 마진과의 관계를 하프 핸드오프와 소프트 핸드오프로 나누어 수치해석을 통해 살펴보았다. outage 확플이 0.1이고 셀 반경을 5-10% 증가시켰을 때 전력제어를 한 경우의 셀 영역비는 3.22 dB-3.99 dB, 전력제어를 하지 않은 경우의 셀 영역비는 2.55 dB-2.85 dB 만큼 증가하는 것을 알 수 있다.

• The Journal of the Korea Contents Association
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• v.11 no.6
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• pp.106-115
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• 2011

In this paper, we evaluate the effectiveness of previous shading algorithms in depicting shape of 3d objects. We perform a study in which people are shown an image of one of ten 3D objects shaded with one of eight styles and asked to orient a gauge to coincide with the surface normal at many positions on the object's surface. The normal estimates are compared with each other and with ground truth data provided by a registered 3D surface model to analyze accuracy and precision. Our experiments suggest that people interpret certain shape differently depending on shading of 3d object. This paper offers substantial evidence that current computer graphics shading algorithms can effectively depict shape of 3d objects where the algorithms have the properties of lots of tone steps and uniformly distributed tone steps. This type of analysis can guide the future development of new CG shading algorithms in computer graphics for the purpose of shape perception.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.257-259
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• 2022

보조수단으로 운용중인 폐쇠회로는 고정된 위치에서 선박들의 이동경로가 파악 가능하여 입출항 관리 시스템 개발에 있어서 중요한 역할을 한다. 이 연구에서는 가우시안 혼합모델을 이용하여 물표를 탐지하고 이동벡터의 계산을 분석하여 매트랩에 적용 가능한 알고리즘을 진행하고자한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.408-422
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• 2000

In this paper, we propose a generalized vector channel model for wireless communication systems using antenna arrays. The proposed channel model reflects path loss. spatial-temporal variation of shadowing, multipath fading , Doppler effect, spatial distribution of local scatterers and delay spread due to remote dominant scatterers. In addition, we use a discrete ray model in which respective ray signal experiences independent shadowing, fading and Doppler shift, and impinges on antenna arrays at a distinct angle. Based on the proposed mode. we derive the relations on the spatial and temporal correlations of the received signals and implement a spatial channel simulator. By comparing the theoretical values with the simulated ones, we verify the effectiveness of the implemented simulator. The simulator is then used to generate an arbitrary channel impulse response and to analyze the channel characteristics under various environments.