Yanzhen (Eric) Wang

I'm currently a Ph.D. student in School of Computer Science, National University of Defense Technology (NUDT), China, under the supervision of Prof. Yueshan Xiong. From Oct. 2009 to Oct. 2010, I visited the GrUVi Lab, School of Computing Science, Simon Fraser University (SFU), working with Prof. Hao (Richard) Zhang. The visit was supported by China Scholarship Concil (CSC).

Email: yanzhen (dot) wang (at) gmail (dot) com
Phone: +86-731-845-73660


Research Interests

  • Computer graphics
  • Shape analysis
  • Virtual reality

Selected Publications

Yanzhen Wang, Kai Xu, Jun Li, Hao Zhang, Ariel Shamir, Ligang Liu, Zhiquan Cheng, and Yueshan Xiong. Symmetry Hierarchy of Man-Made Objects. Computer Graphics Forum (Special Issue of Eurographics 2011), to appear, 2011. [Project page]

Abstract: We introduce symmetry hierarchy of man-made objects, a high-level structural representation of a 3D model providing a symmetry-induced, hierarchical organization of the model's constituent parts. Given an input model segmented into primitive parts, we first build an initial graph which encodes inter-part symmetry and connectivity relations, as well as self-symmetries in individual parts. The symmetry hierarchy is constructed from the initial graph via recursive graph contraction consisting of two operations: groupingof parts by symmetries and assembly of connected sets of parts. The order of graph contraction is dictated by a set of precedence rules designed primarily to respect the law of symmetry in perceptual grouping and the principle of compactness of representation. The symmetry hierarchy of a man-made object naturally implies a hierarchical segmentation that is more meaningful than those produced by local geometric considerations. We demonstrate that such a hierarchical segmentation facilitates intra-class semantic labeling of shapes. We also develop applications of symmetry hierarchies for structural shape editing and detection of upright orientations.

Kai Xu, Zhiquan Cheng, Yanzhen Wang, Yueshan Xiong, and Hao Zhang. Quality Encoding for Tetrahedral Mesh Optimization. Computers and Graphics (Special Issue of Shape Modeling International 2009), vol. 33, pp. 250-261, 2009. [PDF]

Abstract: We define quality differential coordinates (QDC) for per-vertex encoding of the quality of a tetrahedral mesh. QDC measures the deviation of a mesh vertex from a position which maximizes the combined quality of the set of tetrahedra incident at that vertex. Our formulation allows the incorporation of different choices of element quality metrics into QDC construction to penalize badly shaped and inverted tetrahedra. We develop an algorithm for tetrahedral mesh optimization through energy minimization driven by QDC. The variational problem is solved efficiently and robustly using gradient flow based on a stable semi-implicit integration scheme. To ensure quality boundary of the resulting tetrahedral mesh, we propose a harmonic-guided optimization scheme which leads to consistent handling of both the interior and boundary tetrahedra.

Yanzhen Wang, Kai Xu, Yueshan Xiong, and Zhiquan Cheng. 2D Shape Deformation Based on As-Rigid-As-Possible Squares Matching. Computer Animation and Virtual World (Special Issue of CASA 2008), vol. 19, pp. 411-420, 2008. [PDF]

Abstract: In this paper, we propose a fast and stable method for 2D shape deformation based on rigid square matching. Our method utilizes uniform quadrangular control meshes for 2D shapes and tries to maintain the rigidity of each square in the control mesh during user manipulation. A rigid shape matching method is performed to find an optimal pure rotational transformation for each square in the control mesh. An iterative solver is proposed to compute the final deformation result for the entire control mesh by minimizing the difference between the deformed vertices and their counterparts in the neighboring rigid square. The deformation result on the 2D shape is as rigid as possible and the details of the shape are preserved well. As extensions, we present a shape-aware splitting method to improve the deformation effect for coarse meshes and a simple sketch-based clustering method for skeletal deformation.

Kai Xu, Yanzhen Wang, Yueshan Xiong, and Zhiquan Cheng. Interactive Shape Manipulation Based on Space Deformation with Harmonic-Guided Clustering. In Proc. Computer Animation and Social Agent 2008, Seoul, Korea, 2008. [PDF]

Abstract: We present an efficient and effective deformation algorithm for interactive shape manipulation. To obtain the advantages of both surface and space-based deformation, we propose to maximally incorporate surface geometry information into space deformation framework while preventing the dependence on surface representation. Our deformation model significantly reduces the problem size through sampling the shape surface and then clustering the sampled points into deformation clusters under the guidance of handle-based harmonic field. The deformation computed on deformation clusters is transferred to the embedded shape through interpolation based on harmonic values...

Zhiquan Cheng, Yanzhen Wang, Bao Li, Kai Xu, Gang Dang, and Shiyao Jin. A Survey of Methods for Moving Least Squares Surfaces. In Proc. IEEE/Eurographics Symposium on Point Based Graphics 2008, Los Angeles, USA, 2008. [PDF]

Abstract: Moving least squres (MLS) surfaces representation directly defines smooth surfaces from point cloud data, on which the differential geometric properties of point set can be conveniently estimated. Nowadays, the MLS surfaces have been widely applied in the processing and rendering of point-sampled models and increasingly adopted as the standard definition of point set surfaces. We classify the MLS surface algorithms into two types: projection MLS surfaces and implicit MLS surfaces, according to employing a stationary projection or a scalar field in their definitions. Then, the properties and constraints of the MLS surfaces are analyzed...

Zhiquan Cheng, Kai Xu, Bao Li, Yanzhen Wang, Shiyao Jin, and Gang Dang. Mesh Segmentation Based on the Extended 3D Short-Cut Rule. In Proc. International Symposium on Visual Computing 2007, Lake Tahoe, USA, 2007. [PDF]

Abstract: In this paper, a hierarchical shape decomposition algorithm is proposed, which integrates the advantages of skeleton-based and minima-rule-based meaningful segmentation algorithms. The method makes use of new geometrical and topological functions of skeleton to define initial cutting critical points, and then employs salient contours with negative minimal principal curvature values to determine natural final boundary curves among parts. And sufficient experiments have been carried out on many meshes, and shown that our framework can provide more reasonable perceptual results than single skeleton-based or minima-rule-based algorithm. In addition, our algorithm not only can divide a mesh of any genus into a collection of genus zero, but also partition level-of-detail meshes into similar parts.

Yanzhen Wang, Yueshan Xiong, Kai Xu, Ke Tan, and Guangyou Guo. A Mass-Spring Model for Surface Mesh Deformation Based on Shape Matching. In Proc. ACM GRAPHITE 2006, pp. 376-380, Kuala Lumpur, 2006. [PDF]

Abstract: In this paper, we propose a mass-spring model based on shape matching for real-time deformable modeling in virtual reality systems. By defining a rigid core for surface mesh model and adding a new generalized spring for each mass, our surface mesh model can preserve its original geometric features such as volume and shape. Then, we use shape matching approaches to update the rigid core of the model dynamically so as to simulate global deformations. At last, we adopt and inverse dynamics technique to deal with the resulting deformations...

Kai Xu, Yueshan Xiong, Yanzhen Wang, Ke Tan, and Guangyou Guo. A Simple and Stable Feature-Preserving Smoothing Method for Contours-Based Reconstructed Meshes. In Proc. ACM GRAPHITE 2006, pp. 391-398, Kuala Lumpur, 2006. [PDF]

Abstract: In this paper, we develop a new feature preserving smoothing method for the irregular and coarse meshes reconstructed from 2D contours. To make the feature detecting robust, a new detecting algorithm using the continuity among adjacent contours is proposed. Then the original mesh is subdivided adaptively according to the detected geometric features and smoothed with isotropic method. With the help of that, our algorithm obtains not only the feature-preserving result of anisotropic methods...