PG2013short

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https://diglib.eg.org/handle/10.2312/998

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Bezier Crust on Quad Subdivision Surface
(The Eurographics Association, 2013) Wang, Jianzhong; Cheng, Fuhua; Bruno Levy and Xin Tong and KangKang Yin
Subdivision surfaces have been widely used in computer graphics and can be classified into two categories, approximating and interpolatory. Representative approximating schemes are Catmull-Clark (quad) and Loop (triangular). Although widely used, one issue remains with the approximating schemes, i.e., the process of interpolating a set of data points is a global process so it is difficult to interpolate large data sets. In this paper, we present a local interpolation scheme for quad subdivision surfaces through appending a G2 Bezier crust to the underlying surface, and show that this local interpolation scheme does not change the curvatures across the boundaries of underlying subdivision patches, therefore, one obtains high quality interpolating limit surfaces for engineering and graphics applications efficiently.
Component-aware Semantic Modeling of Architectures from a Single Image
(The Eurographics Association, 2013) Hou, Fei; Zhao, Qinping; Qi, Yue; Qin, Hong; Bruno Levy and Xin Tong and KangKang Yin
This paper advocates a new component-aware framework to reconstruct 3D architecture from a single image. Different from existing work, our motivation is to obtain a complete set of semantically-correct 3D architectural components, which enables part reusability towards rapid model reproduction and facilitate model variation. The core of our system is a novel algorithm to adaptively segment repeated curved stripes (e.g., roof tiles, building floors) into individual elements, based on which 3D dimensions as well as architectural components are derived from a single image. Specially for Chinese architectures, we further devise an interactive method to identify outer columns based on user-specified inner columns. Finally, 3D components are generated and shape rules are derived, from which the buildings and their variants are constructed. Our new component-aware framework emphasizes component utility during rapid 3D architecture reproduction.
Video-Realistic Inner Mouth Reanimation
(The Eurographics Association, 2013) Kawai, Masahide; Iwao, Tomoyori; Maejima, Akinobu; Morishima, Shigeo; Bruno Levy and Xin Tong and KangKang Yin
We propose a novel post-effect method that can make an existing speech animation video-realistic by generating an inner mouth appearance that is tailored to the speaker. The automatic generation of photorealistic inner mouth appearances requires only simple inputs and small databases and is not restricted by video lighting. The approach is also applicable for creature speech animation with human voices. Our system uses two key algorithms; one of the algorithms models the inner mouth appearances based on physical assumptions, and the other algorithm synthesizes the inner mouth images with care taken to maintain time continuity and luminance gradients.
Non-rigid 3D Shape Retrieval via Sparse Representation
(The Eurographics Association, 2013) Wan, Lili; Li, Shuai; Miao, Zhenjiang J.; Cen, Yigang G.; Bruno Levy and Xin Tong and KangKang Yin
Shape descriptor design is an important but challenging problem for non-rigid 3D shape retrieval. Recently, bagof- words based methods are widely used to integrate a model's local shape descriptors into a global histogram. In this paper, we present a new method to pool the local shape descriptors into a global shape descriptor by means of sparse representation. Firstly, we employ heat kernel signature (HKS) to depict the multi-scale local shape. Then, for each model in the training dataset, we take the HKSs corresponding to its mesh vertices to serve as training signals, and thus an over-complete dictionary can be learned from them. Finally, the HKSs of each 3D model are sparsely coded based on the learned dictionary, and such sparse representations can be further integrated to form an object-level shape descriptor. Moreover, we conduct extensive experiments on the state-of-the-art benchmarks, wherein comprehensive evaluations state our method can achieve better performance than other bag-of-words based approaches.
Modeling Large Scale Clouds from Satellite Images
(The Eurographics Association, 2013) Yuan, Chunqiang; Liang, Xiaohui; Hao, Shiyu; Yang, Guang; Bruno Levy and Xin Tong and KangKang Yin
Visualization of satellite cloud images plays an important role in atmosphere analysis and weather prediction. However, reconstruction of meaningful 3D clouds is a challenging problem due to the 2D nature of the input data. In this paper, we present a new method for modeling large scale clouds based on cloud property retrieval theory. In contrast with previous methods, the proposed one is more physical and focuses on the geometric structures of clouds. Image pixels are first divided into cloudlessness, water cloud, ice cloud, and thin cirrus cloud in terms of spectral characteristics. Then, the top height, geometry thickness and extinction volume of the cloud are generated by applying different spectral combinations of images. Finally, clouds are rendered with various light directions or view directions. The results show that the proposed method can not only yield realistic clouds, but also approximate actual clouds, thus being useful for time critical applications.
Backwards Memory Allocation and Improved OIT
(The Eurographics Association, 2013) Knowles, Pyarelal; Leach, Geoff; Zambetta, Fabio; Bruno Levy and Xin Tong and KangKang Yin
Order independent transparency (OIT) is a graphics technique which sorts surfaces per-pixel for correct alpha blending. The sorting stage requires relatively large amounts of temporary memory in shaders that is usually conservatively allocated at a maximum, which impacts occupancy and performance. To address this issue we introduce backwards memory allocation (BMA), a strategy which creates a set of shaders with varying static allocation size in lieu of dynamic allocation. Batches of threads are then executed directly with the appropriate shader. This also allows optimizations for each generated shader such as choosing the sorting algorithm based on allocation size with no additional overhead. BMA gives both a more flexible OIT (BMA-OIT) for dynamic scenes of varying depth complexity and up to a 3x speedup.
Fast Random Sampling of Triangular Meshes
(The Eurographics Association, 2013) Sik, Martin; Krivanek, Jaroslav; Bruno Levy and Xin Tong and KangKang Yin
We present a simple and fast algorithm for generating randomly distributed points on a triangle mesh with probability density specified by a two-dimensional texture. Efficiency is achieved by resampling the density texture on an adaptively subdivided version of the input mesh. This allows us to generate the samples up to 40 x faster than the rejection sampling algorithm, the fastest existing alternative. We demonstrate the algorithm in two applications: fast placement of hair roots on a surface and sampling of illumination from a complex luminaire. Part of our mesh sampling procedure is a new general acceleration technique for drawing samples from a 1D discrete probability distribution whose utility extends beyond the mesh sampling problem.
Exploring Volume Visualization with Whole-hand Multitouch Gestures
(The Eurographics Association, 2013) Yan, Xiaoqi; Song, Peng; Fu, Chi-Wing; Goh, Wooi Boon; Ma, Kwan-Liu; Bruno Levy and Xin Tong and KangKang Yin
Exploded views and cutaway views have been demonstrated to be powerful visualization techniques to explore the complex internal structures in 3D volume data. Current approaches for creating them are mainly based on algorithms with very limited user controls. This paper proposes a novel set of whole-hand multitouch gestures for interactive creation and manipulation of these views on 3D volume data. Moreover, users can also interactively perform bimanual 'V'-shape cut and volume exploding, remove unwanted volume partitions to effectively create cutaway views, and create threshold-based volume segmentation and exploded views. Our proposed interaction design was also tried out by eight participants in a preliminary pilot study.
Intelligent Interactive Volume Classification
(The Eurographics Association, 2013) Grau, Sergi; Puig, Anna; Escalera, Sergio; Salamó, Maria; Bruno Levy and Xin Tong and KangKang Yin
This paper defines an intelligent and interactive framework to classify multiple regions of interest from the original data on demand, without requiring any preprocessing or previous segmentation. The proposed intelligent and interactive approach is divided in three stages: visualize, training and testing. First, users visualize and label some samples directly on slices of the volume. Training and testing are based on a framework of Error Correcting Output Codes and Adaboost classifiers that learn to classify each region the user has painted. Later, at the testing stage, each classifier is directly applied on the rest of samples and combined to perform multi-class labeling, being used in the final rendering. We also parallelized the training stage using a GPU-based implementation for obtaining a rapid interaction and classification.
An Improved Friction Model for Cloth Simulation
(The Eurographics Association, 2013) Wong, Tszho H.; Leach, Geoff; Zambetta, Fabio; Bruno Levy and Xin Tong and KangKang Yin
Friction is a complex phenomenon that resists tangential motion between two contacting objects. In computer graphics, existing cloth simulation methods have typically used a Coulomb model for friction, both static and kinetic. However, the Coulomb model is limited since it intends to capture fundamental frictional phenomena. Many observed friction effects such as stiction, Stribeck friction, viscous friction and the stick-slip phenomenon are not modelled by it. This paper describes an improved physically based friction model for simulating such effects, extending the Coulomb model.We show that including these additional effects is relatively straightforward. Results and comparisons with a pure Coulomb model are provided to demonstrate the capability and features of the improved model.
Interactive Exploration of 4D Geometry with Volumetric Halos
(The Eurographics Association, 2013) Wang, Weiming M.; Yan, Xiaoqi Q.; Fu, Chi-Wing; Hanson, Andrew J.; Heng, Pheng Ann; Bruno Levy and Xin Tong and KangKang Yin
Halos have been employed as a compelling illustrative hint in many applications to promote depth perception and to emphasize occlusion effects among projected objects. We generalize the application of halo methods from the widely-used domain of 2D projections of 3D objects to the domain of 3D projections of 4D objects. Since 4D imaging involves a projection from 4D geometry (such as a surface with 4D vertices) to a 3D image, such projection typically produces intersecting surfaces, and thus occlusion phenomena result in apparent curves in 3D space. Adding volumetric halos to the surfaces then gives useful information about the spatial relations of intersecting surfaces, and allows a more accurate perception of the geometry. A typical application is knotted spheres embedded in 4D, and the volumetric halos perform the same function as traditional knot diagrams do in 2D drawings of 3D knotted curves. In addition, we design a series of GPU-based algorithms to achieve real-time updating of the halo-enhanced image when the geometry is interactively rotated in 4D.

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