Computer Animation and Virtual Worlds

Cover image for Vol. 22 Issue 2‐3

Special Issue: CASA' 2011 Special Issue

April - May 2011

Volume 22, Issue 2-3

Pages 1–332

Issue edited by: Zhigeng Pan, Nadia Magnenat-Thalmann, Jinxiang Chai

  1. Issue Information

    1. Top of page
    2. Issue Information
    3. Editorials
    4. Special Issue Papers
    1. You have free access to this content
      Issue Information (pages i–ii)

      Version of Record online: 18 APR 2011 | DOI: 10.1002/cav.420

  2. Editorials

    1. Top of page
    2. Issue Information
    3. Editorials
    4. Special Issue Papers
    1. You have free access to this content
      Editorial (pages 79–80)

      Zhigeng Pan, Nadia Magnenat-Thalmann and Jinxiang Chai

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.419

  3. Special Issue Papers

    1. Top of page
    2. Issue Information
    3. Editorials
    4. Special Issue Papers
    1. Modeling ocean waves and interaction between objects and ocean water for cartoon animation (pages 81–89)

      Jing Liao, Jinhui Yu and John Patterson

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.400

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      This article presents a procedural model for the animation of ocean waves in a recognizable drawn animation cartoon style. With minimum user intervention, i.e., specification of a few parameters, our model is able to generate the cartoon animation of ocean waves and interaction between objects and ocean water.

    2. Feature-based vector simulation of water waves (pages 91–98)

      Qizhi Yu, Fabrice Neyret and Anthony Steed

      Version of Record online: 7 APR 2011 | DOI: 10.1002/cav.391

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      We present a method for simulating local water waves caused by obstacles in water streams for real-time graphics applications. The geometric shapes of the waves is intuitively controllable. Our method also has good compatibilities with other water wave or water flow models.

    3. Interactive soft-fabrics watering simulation on GPU (pages 99–106)

      Chen Huang, Hanqiu Sun, Shiguang Liu and Ping Li

      Version of Record online: 7 APR 2011 | DOI: 10.1002/cav.402

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      Efficient dynamics models for the real-time simulation of soft fabrics interacting with water, including multi-soaking effect and underwater dynamics. When integrated with GPU–CUDA acceleration, our method is feasible for real-time VR applications with large set of fabric particles.

    4. Real-time smoke simulation with improved turbulence by spatial adaptive vorticity confinement (pages 107–114)

      Shengfeng He, Hon-Cheng Wong, Wai-Man Pang and Un-Hong Wong

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.408

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      In this paper, we propose a novel approach to enhance the visual effect by employing an adaptive vorticity confinement which varies the strength with respect to the helicity instead of a user-defined constant. To further improve fine details in turbulent flows, we are not only applying our proposed vorticity confinement to low-resolution grid, but also on a finer grid to generate sub-grid level turbulence. Several experiments demonstrate that our method can produce realistic smoke animation with enhanced turbulence effects in real-time.

    5. Meshless simulation of brittle fracture (pages 115–124)

      Ning Liu, Xiaowei He, Sheng Li and Guoping Wang

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.412

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      We propose a meshless method to simulate brittle fracture with physical accuracy as well as user controllability.

    6. Realistic, fast, and controllable simulation of solid combustion (pages 125–132)

      Jian Zhu, Yuanzhang Chang and Enhua Wu

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.394

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      We proposed a combustion model that not only visually simulates fire propagation on burning solids but also physically models the underlying decomposition process. A hybrid structure of grids is employed to simulate the whole process efficiently. An improved burning surface update scheme and a novel method for visualizing the burning surface help to produce convincing results. To achieve interactive simulation speed, a few acceleration techniques are proposed. Finally, we are able to simulate various solid combustion phenomena.

    7. Simulation theory and anticipation for interactive virtual character in an uncertain world (pages 133–139)

      Cédric Buche, Anne Jeannin-Girardon and Pierre De Loor

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.401

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      This article presents the use of internal simulation to provide the ability to anticipate for agents. This study is apply to an artificial juggler (called JABU), which predicts the motion of balls in the air and uses its predictions to coordinate its own behavior while juggling.

    8. UEGM: uncertain emotion generator under multi-stimulus (pages 141–149)

      Nan Xiang, Haiying Zhao, Xiaojian Zhou, Mingliang Xu, Abdennour El Rhalibi and Yu Wu

      Version of Record online: 13 APR 2011 | DOI: 10.1002/cav.411

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      A novel particle filtering architecture to simulate uncertain emotion generation under multi-stimulus is introduced in this paper, to enrich emotions for virtual characters. Particles are exploited to predict emotions by sampling possible natural emotional reactions from individuals' memories and common reactions, and the prediction is subsequently adjusted through likelihood function constructed through appraisals of the cognitive component. Thus this generation process combines the natural reactions and cognitive results of individuals' into a unified architecture.

    9. Footstep navigation for dynamic crowds (pages 151–158)

      Shawn Singh, Mubbasir Kapadia, Glenn Reinman and Petros Faloutsos

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.403

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      We present a new navigation technique that outputs footsteps instead of vector-based steering decisions. Our approach produces unambiguous, biomechanically correct steps, including the placement, orientation, and timing of each footstep. This method can navigate crowds of characters in real-time through tight, tricky situations with spatial precision, temporal precision, and natural behavior.

    10. A framework for locally retargeting and rendering facial performance (pages 159–167)

      Ko-Yun Liu, Wan-Chun Ma, Chun-Fa Chang, Chuan-Chang Wang and Paul Debevec

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.404

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      We present a facial motion retargeting method that allows a blendshape rig to create facial expressions and conforms best to the current motion capture input. An automatic segmentation technique based on the analysis of facial motion is introduced to create facial regions for local retargeting. We also show that it is possible to blend normal maps for rendering in the same framework, which significantly improves surface appearance and details.

    11. Easy acquisition and real-time animation of facial wrinkles (pages 169–176)

      Ludovic Dutreve, Alexandre Meyer and Sada Bouakaz

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.395

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      In this paper, we propose a mono-camera acquisition technique of facial animation details and a technique which add a wrinkle map layer (fine-scale animation) to a skinning layer (large-scale animation) for real-time rendering of a virtual 3D face. The acquisition is based on ratio image computed from two pictures of a same face, with and without expression. The real-time dynamic wrinkles technique is based on a small set of reference poses.

    12. Multi-layer structural wound synthesis on 3D face (pages 177–185)

      Chung-Yeon Lee, Sangyong Lee and Seongah Chin

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.399

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      In this paper, we propose multi-layer structural wound synthesis on a 3D face. This approach first defines the facial tissue depth map (FTDM), composed of tissue layers of facial skin, including epidermis, dermis and subcutis. Each layer of skin in a wound image has been determined by hue-based segmentation and wound depth has been calculated using the relative distance to the maximum depth for the layer. To realise the volumetric geometry for a wound patch, we have designed disparity-based 3D shape augmentation. Finally, this approach has been validated using 3D wound simulation experiments.

    13. Characteristic facial retargeting (pages 187–194)

      Jaewon Song, Byungkuk Choi, Yeongho Seol and Junyong Noh

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.414

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      With this method, human face motion from captured data is effectively and stylistically retargeted onto several non-humanoid character faces. We propose the hybrid retargeting model, which combines the RBF and kCCA-based regression method. 1D Laplacian motion warping follows after retargeting, changing the timing of the retargeted animation and thus, representing the characteristics of the target face.

    14. Automatic reconstruction of personalized avatars from 3D face scans (pages 195–202)

      Michael Zollhöfer, Michael Martinek, Günther Greiner, Marc Stamminger and Jochen Süßmuth

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.405

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      We present a simple algorithm for computing a high-quality personalized avatar from a single color image and the corresponding depth map which have been captured by Microsoft's Kinect sensor. Due to the low market price of our hardware setup, 3D face scanning becomes feasible for home use. The proposed algorithm combines the advantages of robust non-rigid registration and fitting of a morphable face model. We obtain a high-quality reconstruction of the facial geometry and texture along with one-to-one correspondences with our generic face model. This representation allows for a wide range of further applications such as facial animation or manipulation.

    15. 3D body scanning with hairstyle using one time-of-flight camera (pages 203–211)

      Jing Tong, Mingmin Zhang, Xueqin Xiang, Huaqing Shen, Hao Yan and Zhengming Chen

      Version of Record online: 13 APR 2011 | DOI: 10.1002/cav.392

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      Capturing realistic 3D shapes of human bodies is useful for many computer graphics applications. For existing 3D shape capturing devices, problems arise when dealing with 3D hairstyle scanning and body deformation. To solve these problems, we present the first method to scan human body with hairstyle using one time-of-flight (TOF) camera. Based on the refinement of temporal average meshes, it is very easy to use, and can reconstruct body shape of reasonable quality in just a few minutes.

    16. Interactive sign language synthesis based on adaptive display resolution visibility for ubiquitous devices (pages 213–220)

      Jun Pan, Jian-min Wang, Shun-ting Cao and Xiao-nan Luo

      Version of Record online: 13 APR 2011 | DOI: 10.1002/cav.409

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      This paper presents a novel framework of synthesizing Chinese Sign Language (CSL) animation on ubiquitous platform-independent devices with consideration of the self-adaptive rendering capability of the device display screen. The Display Resolution Visibility (DRV) Factor is introduced here as the measurement of the system's adaptability. Consequently, a real-time transmission scheme is proposed for sign language animation over a heterogeneous network.

    17. Predicting missing markers in human motion capture using l1-sparse representation (pages 221–228)

      Jun Xiao, Yinfu Feng and Wenyuan Hu

      Version of Record online: 13 APR 2011 | DOI: 10.1002/cav.413

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      We handle the predicting missing marker problem from the perspective of sparse representation and proposed a novel method named L1-SRMMP. Meanwhile, a simple but effective algorithm named PCWU has been used to update the training set. Experiment results demonstrate the effectiveness of our algorithm and that it is much suitable for the repetitive motion data than the non-repetitive ones.

    18. Real-time mocap dance recognition for an interactive dancing game (pages 229–237)

      Liqun Deng, Howard Leung, Naijie Gu and Yang Yang

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.397

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      We present an interactive dancing game based on motion capture technology. We address the problem of real-time recognition of the user's live dance performance in order to determine the interactive motion to be rendered by a virtual dance partner. We present our flexible matching method and several rules which contribute to the good performance on both continuous motion recognition and unwanted motion detection.

    19. Efficient camera path planning algorithm for human motion overview (pages 239–250)

      I-Cheng Yeh, Chao-Hung Lin, Hung-Jen Chien and Tong-Yee Lee

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.398

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      This paper proposes an efficient approach of finding the camera path for human motion and can potentially enable interactive camera control. Instead of solving a complicated camera optimization problem, we heuristically determine the camera path-based on an efficient greedy-based tree traversal approach. The experimental results show that the proposed approach generate a smooth, informative, and aesthetic motion over view efficiently.

    20. 3D soft tissue warping dynamics simulation based on force asynchronous diffusion model (pages 251–259)

      Weixin Si, Zhiyong Yuan, Xiangyun Liao, Zhaoliang Duan, Yihua Ding and Jianhui Zhao

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.416

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      A novel simulation method named FADM (Force Asynchronous Diffusion Model) for 3D soft tissue warping is presented. It can achieve good warping effects on speed and realism. From left to right, the warping effects of point force and plane force on the soft tissue are shown in this figure.

    21. A new approach to haptic rendering of guidewires for use in minimally invasive surgical simulation (pages 261–268)

      D. Huang, W. Tang, T. R. Wan, N. W. John, D. Gould, Y. Ding and Y. Chen

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.417

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      In this paper, we present a novel approach to model haptics of guidewire insertion process for training simulation purposes. We design a coupling scheme, connecting the virtual tool to the end of the guidewire directly, and compute the feedback force through constrained dynamics. Experimental results highlight the usability of our algorithm for simulating insertion procedures with complex blood vessel structures.

    22. Practical craniofacial surgery simulator based on GPU accelerated lattice shape matching (pages 269–276)

      Sheng-Hui Liao, Yixiong Liang, Ling-Zhi Li, Bei-Ji Zou, Xing-Hao Zhu and Wei Ai

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.393

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      This paper presents an intuitive and practical craniofacial surgery simulation system, based on a GPU accelerated lattice shape matching method, incorporating physical inhomogeneous material as well as orthotropic behavior, to provide high quality prediction of post-operative appearance for a variety of surgeries including osteotomies, bone fragment repositioning, and insertion of implants.

    23. A virtual endoscopy system for virtual medicine (pages 277–284)

      Yanjun Peng, Ruisheng Jia, Yuanhong Wang and Mingmin Zhang

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.418

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      Path planning and navigation images in virtual endoscopy system for virtual medicine.

    24. GPU-friendly shape interpolation based on trajectory warping (pages 285–294)

      Lu Chen, Jin Huang, Hongxin Zhang and Wei Hua

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.407

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      In this paper, we propose a GPU-friendly shape interpolation method. The basic idea is to compute proper parameters of a close-form non-linear vertex trajectory representation in the pre-computing stage and interpolate the intermediate shape vertices in parallel in the run-time. Our method demonstrates that the intermediate shape of as-rigid-as-possible shape interpolation can be reconstructed in GPU without solving any equation.

    25. A graph-based shape matching scheme for 3D articulated objects (pages 295–305)

      Min-Wen Chao, Chao-Hung Lin, Chih-Chieh Chang and Tong-Yee Lee

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.396

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      The underlying graph structure of a given 3D model is composed of its topological skeleton and local geometric features. And two graphs are embedded on a high-dimensional space, then matched based on an extension of Earth Mover's Distance (EMD). Furthermore, the symmetric components of an articulated object are determined by a voting algorithm with a self-matching strategy to refine the matching correspondences.

    26. Efficient wavelet-based geometry compression (pages 307–315)

      Chong Zhao, Hanqiu Sun and Kaihuai Qin

      Version of Record online: 7 APR 2011 | DOI: 10.1002/cav.410

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      In this paper, we present a novel efficient wavelet-based compression approach using the matrix-valued Loop subdivision on triangular meshes. Comparing with the compression method using globally optimised wavelet (PGC), our method has similar compression ratio and much more efficiency, by using the local lifting and shape control ability introduced by matrix-valued subdivision. The above figure shows the compression ratios (PSNR) at various bit rates of different compression schemes.

    27. Stereoscopic image generation of background terrain scenes (pages 317–323)

      Huicheol Hwang, Kyehyun Kim, Roger Blanco i Ribera and Junyong Noh

      Version of Record online: 12 APR 2011 | DOI: 10.1002/cav.415

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      The reconstruction of 3D terrain geometry from images is essential for compositing CG objects into a live-action background or for 2D to 3D conversion of terrain scenes. We present a novel method that automatically generates stereoscopic images of terrain scenes. In addition, our method simplifies identification and compositing of foreground objects on the terrain geometry.

    28. Paint-on-glass animation: the fellowship of digital paint and artisanal control (pages 325–332)

      Tom Van Laerhoven, Fabian Di Fiore, William Van Haevre and Frank Van Reeth

      Version of Record online: 7 APR 2011 | DOI: 10.1002/cav.406

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      In this paper we deal with making animated films by pushing around wet media directly under the camera, known as paint-on-glass animation. Our approach offers the animator an interactive paint system that adopts physically based algorithms to simulate the complex interaction of a virtual canvas with different paint media, and a set of digital tools while preserving all artisan control. A tangible interface allows users to intuitively manipulate the drawing media using their own hands.

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