Guiqing Li

L 1 -medial skeleton of point cloud

We introduce L1-medial skeleton as a curve skeleton representation for 3D point cloud data. The L1-median is well-known as a robust global center of an arbitrary set of points. We make the key observation that adapting L1-medians locally to a point set representing a 3D shape gives rise to a one-dimensional structure, which can be seen as a localized center of the shape. The primary advantage of our approach is that it does not place strong requirements on the quality of the input point cloud nor on the geometry or topology of the captured shape. We develop a L1-medial skeleton construction algorithm, which can be directly applied to an unoriented raw point scan with significant noise, outliers, and large areas of missing data. We demonstrate L1-medial skeletons extracted from raw scans of a variety of shapes, including those modeling high-genus 3D objects, plant-like structures, and curve networks.

2 Subdivision for quadrilateral meshes

This paper presents a

A New Interpolatory Subdivision for Quadrilateral Meshes

\sqrt2

Saliency-driven scaling optimization for image retargeting

subdivision scheme for quadrilateral meshes that can be regarded as an extension of a 4-8 subdivision with new subdivision rules and improved capability and performance. The proposed scheme adopts a so-called

Interpolatory ternary subdivision surfaces

\sqrt2

Engineering design of thermal quality clothing on a simulation-based and lifestyle-oriented CAD system

split operator to refine a control mesh such that the face number of the refined mesh generally equals the edge number and is thus about twice the face number of the coarse mesh. Smooth rules are designed in reference to the 4-8 subdivision, while a new set of weights is developed to balance the flatness of surfaces at vertices of different valences. Compared to the 4-8 subdivision, the presented scheme can be naturally generalized for arbitrary control nets and is more efficient in both space and computing time management. Analysis shows that limit surfaces produced by the scheme are C4 continuous for regular control meshes and G1 continuous at extraordinary vertices.

Computer Graphics in China: Convergence analysis for B-spline geometric interpolation

This paper presents a new interpolatory subdivision scheme for quadrilateral meshes based on a 1–4 splitting operator. The scheme generates surfaces coincident with those of the Kobbelt interpolatory subdivision scheme for regular meshes. A new group of rules are designed for computing newly inserted vertices around extraordinary vertices. As an extension of the regular masks,the new rules are derived based on a reinterpretation of the regular masks. Eigen‐structure analysis demonstrates that subdivision surfaces generated using the new scheme are C1 continuous and, in addition, have bounded curvature.

Approximation of Loop Subdivision Surfaces for Fast Rendering

This paper proposes a saliency-weighted scaling factor energy for image retargeting. Considering that salient objects should be scaled with a larger scaling factor with respect to nonsalient regions, we define a quadric energy to establish the relation between the scaling factor of a local region and its saliency. The quadric energy is the weighted sum of the square of scaling factors, where the weight of each scaling factor is inversely proportional to its corresponding saliency. Furthermore, a triangle similarity quadric energy is introduced to prevent salient regions from distortion. Compared to previous methods, our approach not only preserves the shapes of salient objects and the integrity of the whole image well, but also reserves more resolution to salient objects in target image even when the aspect ratio is unchanged.

Composite 2 subdivision surfaces

This paper proposes an interpolatory ternary subdivision for quadrilateral meshes that produces C2 continuous limit surfaces for regular meshes while achieves G1 continuity with bounded curvature at extraordinary vertices. The subdivision splits each quad into nine by inserting two E-vertices onto each edge and four F-vertices onto each face, and connecting them along vertical and horizontal directions respectively. The regular subdivision masks of the scheme are obtained as tensor products of the masks of the interpolatory ternary subdivision for curves while irregular geometric rules are established based on discrete Fourier transformation. For efficient practical use, an adaptive refinement algorithm is developed based on the decomposition of intermediate meshes into divisible and indivisible subsets for each refinement.

IDSS: A Novel Representation for Woven Fabrics

Engineering design of thermal quality clothing is a promising solution by applying multi-disciplinary knowledge to achieve the design and production of clothing with desirable thermal functions. In this paper, a special simulation-based and lifestyle-oriented CAD system is introduced to help the user in engineering design of thermal quality clothing. The engineering-oriented simulation models endowed with explicit data availability arose from the material parameters that are the key issue for engineering application. To offer an easy-to-use tool, this system is implemented with a lifestyle-oriented design procedure. It can facilitate the designers to quickly implement design and simulate on the wearing scenario, and evaluate and optimize their design. Due to the design of thermal quality clothing can be achieved without making physical prototypes, it is able to speed up the design cycle and reduce the design and development cost.