• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.522-526
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• 2008

모션 캡쳐 장비는 사람의 자연스러운 행동이나 동작 정보를 정밀하게 얻기 위해 널리 사용되며, 영화나 게임과 같은 콘텐츠에서 자주 활용되고 있다. 하지만 모션 캡쳐 장비가 고가이기 때문에 한번 입력받은 데이터를 모션별로 분할하고 상황에 맞게 재결합하여 사용할 필요가 있으며, 입력 데이터를 모션별로 분할하는 것은 대부분 수동으로 이루어진다. 이 때문에 캡쳐된 데이터를 자동으로 분할하기 위한 연구들이 다양하게 시도되고 있다. 기존의 연구들은 크게 전역적 특성에 대한 고려없이 이웃하는 프레임만을 고려하는 온라인 방식과 데이터를 전역적으로 고려하나 이웃하는 프레임 사이의 관계를 고려하지 않는 오프라인 방식으로 나누어진다. 본 논문에서는 온라인과 오프라인 방식을 병합한 그래프 기반의 모션 분할 방법을 제안한다. 분할을 위해 먼저 모션데이터를 기반으로 그래프를 생성하며, 그래프는 이웃하는 각 프레임사이의 유사도뿐만 아니라 시간축을 기반으로 일정시간내의 프레임들의 유사도를 모두 고려하였다. 이렇게 생성된 그래프를 분할하기 위해 분할된 모션내의 유사도 합을 최소화하고 각 모션간의 유사도는 최대화할 수 있는 normalized cuts을 이용하였다. 실험에서 제안된 방법은 기존의 오프라인 방식 중 하나인 GMM과 온라인 방식 중 하나인 국부최소값 분할 방법보다 좋은 결과를 보였으며, 이는 각 프레임 사이의 유사도뿐만 아니라 일정시간내의 유사도를 전역적으로 고려하기 때문이다.

• Journal of the Korea Computer Graphics Society
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• v.10 no.2
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• pp.51-56
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• 2004

모션 데이터들을 그래프로 저장하고 이를 모션합성에 이용하는 기존의 연구들은, 모든 모션 프레임간 연결비용계산으로 인하여 그래프 생성에 많은 시간이 걸린다는 단점이 있다. 본 논문에서는 이런 단점을 보완하여 빠르고 효과적으로 그래프를 생성하는 방법을 제시한다. 우선, PCA를 이용하여 모션들을 2차원에 투영시키고, 2차원 상의 간단한 거리계산으로 전이에지가 존재할 가능성이 큰 프레임 쌍들을 찾아낸다. 다음으로, 이런 프레임 쌍에 대해서만 연결비용을 계산하여 그래프를 생성한다. 따라서, 모든 프레임에 대한 비용계산에 비해 본 논문에서 제안한 방법은 효율적으로 그래프를 생성하게 된다.

• Journal of KIISE:Software and Applications
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• v.35 no.11
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• pp.671-680
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• 2008

Motion capture devices have been utilized in producing several contents, such as movies and video games. However, since motion capture devices are expensive and inconvenient to use, motions segmented from captured data was recycled and synthesized to utilize it in another contents, but the motions were generally segmented by contents producers in manual. Therefore, automatic motion segmentation is recently getting a lot of attentions. Previous approaches are divided into on-line and off-line, where ow line approaches segment motions based on similarities between neighboring frames and off-line approaches segment motions by capturing the global characteristics in feature space. In this paper, we propose a graph-based high-level motion segmentation method. Since high-level motions consist of repeated frames within temporal distances, we consider similarities between neighboring frames as well as all similarities among all frames within the temporal distance. This is achieved by constructing a graph, where each vertex represents a frame and the edges between the frames are weighted by their similarity. Then, normalized cuts algorithm is used to partition the constructed graph into several sub-graphs by globally finding minimum cuts. In the experiments, the results using the proposed method showed better performance than PCA-based method in on-line and GMM-based method in off-line, as the proposed method globally segment motions from the graph constructed based similarities between neighboring frames as well as similarities among all frames within temporal distances.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.1
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• pp.44-52
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• 2008

In this paper we consider detecting collisions between characters whose motion is specified by motion capture data. Since we are targeting on massive crowd simulation, we only consider rough collisions, modeling the characters as a disk in the floor plane. To provide efficient collision detection, we introduce a hierarchical bounding volume, the Motion Oriented Bounding Box tree (MOBB tree). A MOBBtree stores space-time bounds of a motion clip. In crowd animation tests, MOBB trees performance improvements ranging between two and an order of magnitude.

• Journal of the Korea Computer Graphics Society
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• v.27 no.1
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• pp.1-8
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• 2021

This paper proposes a simple deformation method for editing the trajectory of a walking motion with preserving its style. To this end, our method analyzes the trajectory of the root joint into the graph and deforms it by applying the graph Laplace operator. The trajectory of the root joint is presented as a graph with a vertex defined the position and direction at each time frame on the motion dataThe graph transforms the trajectory into the differential coordinate, and if the constraints are set on the trajectory vertex, the solver iterative approaches to the solution. By modifying the root trajectory, we can continuously vary the walking motion, which reduces the cost of capturing a whole motion that is required. After computes the root trajectory, other joints are copied on the root and post-processed as a final motion. At the end of our paper, we show the application that the character continuously walks in a complex environment while satisfying user constraints.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.73-76
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• 2013

본 논문은 방송 콘텐츠에서 사용할 수 있는 터치리스 형태의 모션기반 인터랙티브 증강현실 어플리케이션을 제안한다. SD 급 해상도를 가진 범용 모션 카메라를 사용하여 HD 해상도의 방송에서 증강현실 어플리케이션을 구현하기 위해서 깊이 영상의 임의 범위를 지정하여, HD 해상도에 매칭시켜 2D 터치리스 영역에서 손의 멀티터치를 인식하게 하였다. 이렇게 인식된 모션을 자주 사용하는 '왼손 클릭', '오른손 클릭', '양손클릭', '스크러빙-상/하/좌/우' 제스쳐를 인식하게 하였으며, '카루젤 메뉴', '막대그래프 메뉴', '슬라이드 메뉴', '큐브 메뉴'를 구현하여 터치리스 형태의 모션기반 인터랙티브 증강현실 어플리케이션을 제안한다. 방송에서 자주 사용하는 그래픽 정보를 연기자나 사회자가 본 논문에서 제안하는 인터랙션 어플리케이션을 통하여 오퍼레이터 없이 스스로 더 능동적으로 정보를 표출할 수 있는 방법을 설명한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.210-211
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• 2007

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.111-117
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• 2008

In this paper, we describes the boxing motion recognition which is used in the part of games, animation. To recognize the boxing motion, we have used two algorithms, one is principle component analysis, the other is dynamic time warping algorithm. PCA is the simplest of the true eigenvector-based multivariate analyses and often used to reduce multidimensional data sets to lower dimensions for analysis. DTW is an algorithm for measuring similarity between two sequences which may vary in time or speed. We introduce and compare PCA and DTW algorithms respectively. We implemented the recognition of boxing motion on the motion capture system which is developed in out research, and depict the system also. The motion graph will be created by boxing motion data which is acquired from motion capture system, and will be normalized in a process. The result has implemented in the motion recognition system with five actors, and showed the performance of the recognition.

• Journal of the Korea Computer Graphics Society
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• v.21 no.2
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• pp.11-20
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• 2015

We present a new interactive technique for directing the motion sequences of an animated character by dragging its specific body part to a desired location in the three-dimensional virtual environment via a hand motion tracking device. The motion sequences of our character is synthesized by reordering subsequences of captured motion data based on a well-known graph representation. For each new input location, our system samples the space of possible future states by unrolling the graph into a spatial search tree, and retrieves one of the states at which the dragged body part of the character gets closer to the input location. We minimize the difference between each pair of successively retrieved states, so that the user is able to anticipate which states will be found by varying the input location, and resultantly, to quickly reach the desired states. The usefulness of our method is demonstrated through experiments with breakdance, boxing, and basketball motion data.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.497-502
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• 2003

Content-based video copy detection is a complementary approach to watermarking. As opposed to watermarking, which relies on inserting a distinct pattern into the video stream, video copy detection techniques match content-based signatures to detect copies of video. Existing typical content-based copy detection schemes have relied on image matching which is based on key frame detection. This paper proposes a motion directional histogram, which is quantized and accumulated the direction of motion, for video copy detection. The video clip is represented by a motion directional histogram as a 1-dimensional graph. This method is suitable for real time indexing and counting the TV CF verification that is high motion video clips.