• Journal of the Korea Computer Graphics Society
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• v.8 no.1
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• pp.37-45
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• 2002

We present a cloth simulation technique that is very stable yet also responsive. The stability of the technique allows the use of a large fixed time step when simulating various types of fabrics and character motions. The animations generated using this technique are strikingly realistic. Wrinkles form and disappear in a quite natural way, which is the feature that most distinguishes textile fabrics from other sheet materials. Significant improvements in both the stability and realism were made possible by overcoming the post-buckling instability as well as the numerical instability. The instability caused by buckling arises from a structural instability and therefore cannot be avoided by simply employing an implicit method. Addition of a damping force may help to avoid instabilities; however, it can significantly degrade the realism of the cloth motion. In this paper, a new buckling model based on immediate buckling assumption is proposed. A cloth element is assumed to reach a stable configuration immediately once it begins to buckle. This assumption makes it possible to simulate the fabric buckling stably without introducing any fictitious damping force. Consequently, it produces highly responsive cloth motion as well as improves the stability by modeling the fabric-specific buckling property adequately.

• Journal of the Korea Computer Graphics Society
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• v.23 no.5
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• pp.67-73
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• 2017

We propose several techniques which can be employed in a 3D fitness program for monitoring and correcting user's posture. To implement a 3D fitness program, improved reference motion generating techniques and visualizing techniques are necessary. First, in order to understand the difference between the user and the reference movement of a professional, a retargeting method between two different body shapes are studied. Second, the problem of self-occlusion, which occurs when using a low-cost depth sensor to represent complex motions, is solved by using a sample database and time consistency. The system proposed in this paper evaluates the user's posture considering the physical characteristics of the user, and then provides feedback to the user.

• Journal of Broadcast Engineering
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• v.8 no.1
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• pp.54-62
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• 2003

This paper presents a Soccer Game 3D Reencatment System which reenact the Important scene like getting a goal with image processing and computer graphics technologies. KBS Research Institute of Technology has developed the 3D Reenactment System of Soccer Game called ‘VPlay' to provide TV viewers with fresh images in soccer games. Vplay generates the reenactment of exciting and important soccer scenes by using computer graphics. Vplay extracts legion of players from video with color information, and then computes precise positions of players on the ground by using global motion estimation model and playground axis transformation model. The results are applied to locomotion generation module that generates the locomotion of virtual characters automatically. Using predefined motion and model library, Vplay reenacts the important scene in a quick and convenient manner Vplay was developed for live broadcasting of soccer games that demands rapid producing time and was used efficiently during past WorldCup and Asian Game.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.205-212
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• 2018

Learning how to express and express the characteristics of acting expressions required by different media is easy to express the acting required in various mediums. The style of acting required by each medium is different depending on the characteristics of the medium. In particular, digital acting using computer graphics technology expresses actors as if they are in the space by imagining the imaginary space. Through computer graphics post-production, the actual space that will be visible on the final screen is completed and creates a story based on the actual situation. The role of digital actors in applying motion capture to movies is becoming increasingly important. Natural cross-reaction acting between live-action actors and digital character actors has become a trend in animation films where only digital actors appear. In animation films, a real actor plays a major role in connecting the characters of a digital actor. The core of a digital actor is the realization of a unique character performance. In the era of trans-media, the importance of digital acting is increasing day by day.

• Journal of the Korea Computer Graphics Society
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• v.27 no.5
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• pp.55-61
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• 2021

The character motion control based on physics simulation using reinforcement learning continue to being carried out. In order to solve a problem using reinforcement learning, the network structure, hyperparameter, state, action and reward must be properly set according to the problem. In many studies, various combinations of states, action and rewards have been defined and successfully applied to problems. Since there are various combinations in defining state, action and reward, many studies are conducted to analyze the effect of each element to find the optimal combination that improves learning performance. In this work, we analyzed the effect on reinforcement learning performance according to the state representation, which has not been so far. First we defined three coordinate systems: root attached frame, root aligned frame, and projected aligned frame. and then we analyze the effect of state representation by three coordinate systems on reinforcement learning. Second, we analyzed how it affects learning performance when various combinations of joint positions and angles for state.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.409-413
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• 2008

최근, 3차원 그래픽스 기술은 애니메이션 필름 제작에 있어서 자주 사용된다. 그러나 많은 애니메이션 필름들은 3차원 그래픽스 기술을 사용하여 제작되더라도, 2차원 셀 애니메이션 효과를 내려고 한다. 3차원 그래픽스 기술을 이용하여 2차원 셀 애니메이션의 효과를 내기 위해서는 렌더링에는 카툰 렌더링이 사용 된다. 그러나 이를 제외하고도 몇 가기 기술이 더 필요한데, 그중 하나가 만화 캐릭터(character)의 만화스러운 움직임이다. 기존의 연구 중에는 기존의 모션을 만화적 모션으로 변형하려는 시도가 있었으나, 셀 애니메이션의 캐릭터 움직임과 차이가 있었다. 또 생성된 모션이 만화적 모션인가 하는 의문에 대한 평가 기준이 없기 때문에, 만화적 모션의 모호성 문제가 발생하였다. 본 논문에서는 직접 애니메이션에서 모션을 얻어내는 시스템을 제안한다. 2차원 애니메이션 동영상에서 2차원 캐릭터의 자세를 보고 3차원 캐릭터의 자세로 반자동 맵핑하여, 3차원 캐릭터의 애니메이션 키 프레임을 생성하고, 이 키 프레임간의 보간을 통해 3차원 캐릭터 애니메이션을 생성한다. 생성된 3차원 캐릭터 애니메이션은 만화적 움직임을 갖게 되며, 2차원 캐릭터의 자세와 움직임을 기준으로 만들었기 때문에, 만화적 모호성을 극복할 수 있다.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.449-455
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• 2004

In aspects of materializing rational and reasonable beauty in motion picture contents design area, it intends to conceptualize the visual design through studies of the invisible area, the virtual space of the dematerialized era, contrary to the commonly practiced visual design area of the concrete substance and to provide an opportunity to gain new senses and the embedded meanings of the motion picture graphics, which are created in the electronic space. Especially, although the invisible phenomenon such as electromagnetic wave exist in space, it was treated as a conceptual subject. However, it intends to seek a design approach about physical, poetical, aesthetical experience of the design in the invisible area, escaped from the limited existing perspective. Based on such theory, it denotes to secure the possibility of new design through the application of sound, rhythm, color and image in fractal design area.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.644-648
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• 2009

Accurate rendering of a virtual scene in real time has been one of important issues for virtual reality (VR) technology. Specular reflection of light has been studied a long time, which is always seen on a metallic object and causes occasionally very strong brightness (highlight). Due to restriction of number of gradation of brightness (usually 256), maximum brightness and contrast ratio, the highlight is relatively weakly represented by displays and projectors. In addition, specular reflection will be take influence of binocular parallax and motion parallax, because it is light to reflect in a specific course. Therefore in this paper, an emphasized highlight model of a metallic object on the CAVE system is proposed. Decreasing brightness slightly on neighbor area of highlighted area, the proposed method increases contrast ratio between the highlighted area and neighbor area. Furthermore, using features of CAVE, the proposed method also represents glance (blink). When a metallic object moves, the method alternatively represents images with highlight and without highlight for both eyes. Since the difference of images for both eyes influences binocular parallax and motion parallax, a userfeels glance more realistically.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.147-153
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• 1998

This paper provides a method for video augmentation using image interpolation. In computer graphics or augmented reality, 3D information of a model object is necessary to generate 2D views of the model, which are then inserted into or overlayed on environmental views or real video frames. However, we do not require any three dimensional model but images of the model object at some locations to render views according to the motion of video camera which is calculated by an SFM algorithm using point matches under weak-perspective (scaled-orthographic) projection model. Thus, a linear view interpolation algorithm is applied rather than a 3D ray-tracing method to get a view of the model at different viewpoints from model views. In order to get novel views in a way that agrees with the camera motion the camera coordinate system is embedded into model coordinate system at initialization time on the basis of 3D information recovered from video images and model views, respectively. During the sequence, motion parameters from video frames are used to compute interpolation parameters, and rendered model views are overlayed on corresponding video frames. Experimental results for real video frames and model views are given. Finally, discussion on the limitations of the method and subjects for future research are provided.

• Journal of Fashion Business
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• v.17 no.1
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• pp.30-41
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• 2013

Augmented reality techniques have been increasingly employed in the textile and fashion industry as well as computer graphics sectors. Three-dimensional virtual clothing CAD systems have also been widely used in the textile industries and academic institutes. Motion tracking techniques are grafted together in the 3D and augmented reality techniques in order to develop the virtual three-dimensional clothing and fitting systems in the fashion and textile industry sectors. In this study, three-dimensional virtual clothing sample has been prepared using a 3D virtual clothing CAD along with a 3D scanning and reconstruction system. Motion of the user has been captured through an RGB-D sensor system, and the virtual clothing fitted on the user's body is allowed to move along with the captured motion flow of the user. Acutal fabric specimens are selected for the material characterization. This study is a primary step toward building a comprehensive system for the user to experience interactively virtual clothing under real environment.