PG: Pacific Graphics Short Papers

Permanent URI for this community

https://diglib.eg.org/handle/10.2312/995

Browse

Browsing PG: Pacific Graphics Short Papers by Subject "and object representations"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Ellipsoidal Cube Maps for Accurate Rendering of Planetary-Scale Terrain Data
    (The Eurographics Association, 2012) Lambers, Martin; Kolb, Andreas; Chris Bregler and Pedro Sander and Michael Wimmer
    Advances in sensor technology lead to a rapidly growing number of terrain data sets with very high spatial resolution. To allow reliable visual analysis of this data, terrain data for planetary objects needs to be rendered with accurate reproduction of every detail. This combination of very large scale and very fine detail is challenging for multiple reasons: the numerical accuracy of typical data types is not sufficient, simple spherical planet models fail to accurately represent the data, and distortions in map projections used for data storage lead to sampling problems. In this paper, we propose the Ellipsoidal Cube Map model to address these problems. We demonstrate the possibilities of the model using a simple renderer implementation that achieves interactive frame rates for a variety of data sets for Earth, Moon, and Mars.
  • Thumbnail Image
    Item
    Incomplete 3D Shape Retrieval via Sparse Dictionary Learning
    (The Eurographics Association, 2015) Wan, Lili; Jiang, Jingyu; Zhang, Hao; Stam, Jos and Mitra, Niloy J. and Xu, Kun
    How to deal with missing data is one of the recurring questions in data analysis. The handling of significant missing data is a challenge. In this paper, we are interested in the problem of 3D shape retrieval where the query shape is incomplete with moderate to significant portions of the original shape missing. The key idea of our method is to grasp the basis local descriptors for each shape in the retrieved database by sparse dictionary learning and apply them in sparsely coding the local descriptors of an incomplete query. First, we present a method of computing heat kernel signatures for incomplete shapes. Next, for each shape in the database, a set of basis local descriptors, which is called a dictionary, is learned and taken as its representative. Finally, a query incomplete shape's heat kernel signatures are respectively reconstructed by each dictionary, and the shape similarities are therefore measured by the reconstruction errors. Experimental results show that the proposed method has achieved significant improvements over previous works on retrieving non-rigid incomplete shapes.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Projecting Points onto Planar Parametric Curves by Local Biarc Approximation
    (The Eurographics Association, 2014) Song, Hai-Chuan; Shi, Kan-Le; Yong, Jun-Hai; Zhang, Sen; John Keyser and Young J. Kim and Peter Wonka
    This paper proposes a geometric iteration algorithm for computing point projection and inversion on surfaces based on local biarc approximation. The iteration begins with initial estimation of the projection of the prescribed test point. For each iteration, we construct a 3D biarc on the original surface to locally approximate the original surface starting from the current projection point. Then we compute the projection point for the next iteration, as well as the parameter corresponding to it, by projecting the test point onto this biarc. The iterative process terminates when the projection point satisfies the required precision. Examples demonstrate that our algorithm converges faster and is less dependent on the choice of the initial value compared to the traditional geometric iteration algorithms based on single-point approximation.