• Journal of the Korea Computer Graphics Society
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• v.23 no.3
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• pp.1-8
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• 2017

In this paper, we introduce a technique to retarget human motion data to the humanoid body in a constrained environment. We assume that the given motion data includes detailed interactions such as holding the object by hand or avoiding obstacles. In addition, we assume that the humanoid joint structure is different from the human joint structure, and the shape of the surrounding environment is different from that at the time of the original motion. Under such a condition, it is also difficult to preserve the context of the interaction shown in the original motion data, if the retargeting technique that considers only the change of the body shape. Our approach is to separate the problem into two smaller problems and solve them independently. One is to retarget motion data to a new skeleton, and the other is to preserve the context of interactions. We first retarget the given human motion data to the target humanoid body ignoring the interaction with the environment. Then, we precisely deform the shape of the environmental model to match with the humanoid motion so that the original interaction is reproduced. Finally, we set spatial constraints between the humanoid body and the environmental model, and restore the environmental model to the original shape. To demonstrate the usefulness of our method, we conducted an experiment by using the Boston Dynamic's Atlas robot. We expected that out method can help the humanoid motion tracking problem in the future.

• Journal of the Korea Computer Graphics Society
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• v.25 no.3
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• pp.85-92
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• 2019

A 3D virtual character playing a role in a digital story-telling has a unique style in its appearance and motion. Because the style reflects the unique personality of the character, it is very important to preserve the style and keep its consistency. However, when the character's motion is directly controlled by a user's motion who is wearing motion sensors, the unique style can be discarded. We present a novel character motion control method that uses only a small amount of animation data created only for the character to preserve the style of the character motion. Instead of machine learning approaches requiring a large amount of training data, we suggest a search-based method, which directly searches the most similar character pose from the animation data to the current user's pose. To show the usability of our method, we conducted our experiments with a character model and its animation data created by an expert designer for a virtual reality game. To prove that our method preserves well the original motion style of the character, we compared our result with the result obtained by using general human motion capture data. In addition, to show the scalability of our method, we presented experimental results with different numbers of motion sensors.

• Journal of the Korea Computer Graphics Society
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• v.29 no.5
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• pp.11-20
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• 2023

In this paper, we propose a novel deep learning-based motion reconstruction approach that facilitates the generation of full-body motions, including finger motions, while also enabling the online adjustment of motion generation delays. The proposed method combines the Vive Tracker with a deep learning method to achieve more accurate motion reconstruction while effectively mitigating foot skating issues through the use of an Inverse Kinematics (IK) solver. The proposed method utilizes a trained AutoEncoder to reconstruct character body motions using tracker data in real-time while offering the flexibility to adjust motion generation delays as needed. To generate hand motions suitable for the reconstructed body motion, we employ a Fully Connected Network (FCN). By combining the reconstructed body motion from the AutoEncoder with the hand motions generated by the FCN, we can generate full-body motions of characters that include hand movements. In order to alleviate foot skating issues in motions generated by deep learning-based methods, we use an IK solver. By setting the trackers located near the character's feet as end-effectors for the IK solver, our method precisely controls and corrects the character's foot movements, thereby enhancing the overall accuracy of the generated motions. Through experiments, we validate the accuracy of motion generation in the proposed deep learning-based motion reconstruction scheme, as well as the ability to adjust latency based on user input. Additionally, we assess the correction performance by comparing motions with the IK solver applied to those without it, focusing particularly on how it addresses the foot skating issue in the generated full-body motions.

• Journal of the Korea Computer Graphics Society
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• v.24 no.3
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• pp.93-100
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• 2018

This paper proposes a small-scale rehabilitation system that allows stroke patients to perform daily rehabilitation training in a virtual home. Stroke patients have limited activities of daily living due to paralysis, and there are many rehabilitation exercises for them to reproduce activities that take place in the house, such as turning lights on and off, door opening and closing, gas valve locking. In this paper, we have implemented a virtual home with the above mentioned daily rehabilitation training elements, by using virtual reality technology. We use Leap Motion, a hand motion recognition device, for rehabilitation of hands and fingers. It is expected that stroke patients can rehabilitate small muscles without having to visit the clinic with uncomfortable body, and will be able to get interesting rehabilitation training by avoiding monotony of existing rehabilitation tools.

• Journal of the Korea Computer Graphics Society
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• v.26 no.4
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• pp.1-8
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• 2020

Motion synthesis using physics-based controllers can generate a character animation that interacts naturally with the given environment and other characters. Recently, various methods using deep neural networks have improved the quality of motions generated by physics-based controllers. In this paper, we present a control policy learned by deep reinforcement learning (DRL) that enables Luxo, the mascot character of Pixar animation studio, to run towards a random goal location while imitating a reference motion and maintaining its balance. Instead of directly training our DRL network to make Luxo reach a goal location, we use a reference motion that is generated to keep Luxo animation's jumping style. The reference motion is generated by linearly interpolating predetermined poses, which are defined with Luxo character's each joint angle. By applying our method, we could confirm a better Luxo policy compared to the one without any reference motions.

• Journal of the Korea Computer Graphics Society
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• v.28 no.2
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• pp.29-41
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• 2022

In this paper, we introduce a novel real-time, interactive animation system which uses real-time motion inputs from a low-cost motion-sensing device Kinect. Our system generates interaction motions between the user character and the counterpart character in real-time. While the motion of the user character is generated mimicking the user's input motion, the other character's motion is decided to react to the user avatar's motion. During a pre-processing step, our system analyzes the reference motion data and generates mapping model in advance. At run-time, our system first generates initial poses of two characters and then modifies them so that it could provide plausible interacting behavior. Our experimental results show plausible interacting animations in that the user character performs a modified motion of user input and the counterpart character properly reacts against the user character. The proposed method will be useful for developing real-time interactive animation systems which provide a better immersive experience for users.

• Journal of the Korea Society of Computer and Information
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• v.24 no.1
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• pp.115-120
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• 2019

In this paper, we propose a system and an intuitive interface that can create an athletic scene among athletes. We allow you to enter motion as if you were playing a game, so that the user's action becomes the player's action. The user can take various actions in front of the motion sensor and control the object flying to him. When a user specifies an opponent to pass or attack, and takes appropriate action in front of the motion sensor, the movement trajectory of the object is automatically generated by the physical optimization technique in accordance with the motion. In this way, you can create scenes where multiple players play together in a virtual environment. The method of this paper will be very useful for rapid prototyping for cinematic trailers of based on athletics games or animations.

• Journal of Korea Multimedia Society
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• v.22 no.1
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• pp.110-116
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• 2019

Virtual reality (VR) sickness can have an influential effect on the viewing quality of VR 3D contents. Particularly, watching the 3D contents on a head-mounted display (HMD) could cause some severe level of visual discomfort. Despite the importance of assessing the VR sickness, most of the recent studies have focused on unveiling the reason of inducing VR sickness. In this paper, we subjectively measure the level of VR sickness induced in the viewing of omnidirectional 3D graphics contents in HMD environment. Apart from that, we propose an objective assessment model that estimates the level of induced VR sickness by calculating the difference between head movement velocity and global camera motion velocity.

• Korean Journal of Heritage: History & Science
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• v.36
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• pp.335-346
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• 2003

With the development of media and computer, Motion Capture system, recently used in the entertainment and computer graphics, is emerging as a new recording method. Motion Capture is a system that records time-varying position of sensors which are attached to a objects and translates it to 3-D coordinate on computer. The motion of object displays the time-varying positions of each sensors that are graphed, or the line connected man-shaped model's movements on the computer monitor. And by adding computer graphic character to it, the various angled images, which are difficult to be perceived on the stage, can be easily recorded. Recently in Japan, Motion Capture system is being actively studied in order to use it in recording and preserving the intangible cultural assets of dance and art. Especially, Warabiza in Tazawako art village at Akita plays the leading role in this area through the project to symbolize and establish the archive of cultural dance, further, Ritsumeikan Univ. is develops the system for coupling the motion capture system to Labanotation. This article introduces the motion capture and it's related studies in Japan, which are being actively studied as a new recording method of intangible cultural assets.

• Journal of Korea Multimedia Society
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• v.16 no.11
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• pp.1348-1356
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• 2013

Disney Animation has showed not only artistic excellence but also technological innovations through a lot of animation films that they released. Especially with the unique concept that free-willed game characters dive into different worlds of games in animation film, received both critical and commercial acclaim for its stunning visuals and outstanding CG (computer graphics) effects. The purpose of this study is to analyze different styles of game worlds, Disney's layout pipeline, and in-house camera capture system used in . This paper analyzes that three game worlds in this film such as Fix-It Felix Jr., Sugar Rush, and Hero's Duty express different styles by using appropriate character animation and camera movements. Especially Hero's Duty game which new in-house camera capture system is extensively used maximizes unseen visuals by perfectly making realistic and believable game world. Disney's newly developed in-house camera capture system, which is used in this film for the first time, allows real camera's motion and shake and real-time camera's movement and correction within animation set. Result of this study proves that this system improves directing of feature animation and enhance efficiency of the layout department's production process. Therefore, it contributes to a great extent to development of animation films' business.