We describe a new parallel sparse matrix-matrix multiplication algorithm in shared memory using a quadtree decomposition. Our preliminary implementation is nearly as fast as the best sequential method on one core, and scales well to multiple cores.

We give a closed-form expression for the average number of n-dimensional quadtree nodes (`pieces' or`blocks') required by an n-dimensional hyper-rectangle aligned with the axes. Our formula includes as special cases the formulae of previous eeorts for 2-dimensional spaces 8]. It also agrees with theoretical and empirical results that the number of blocks depends on the hyper-surface of the hype...

Unlike the traditional online game infrastructure—the central server approach, we propose a hybrid scheme for multiplayer online games in this paper. This scheme effectively combines the peer-to-peer model and client-server model to solve the problems of scalability, performance and cost limitation. This scheme is suitable for online games playing in a geographical area in which the online play...

This paper reports two efficient quadtree-based algorithms for variable-size block matching (VSBM) motion estimation. The schemes allow the dimensions of blocks to adapt to local activity within the image, and the total number of blocks in any frame can be varied while still accurately representing true motion. This permits adaptive bit allocation between the representation of displacement and ...

In this paper, an object-based embedded image coding algorithm based on context classification and quadtree ordering in wavelet packet domain (OB-CCAQO) is proposed. To match up well with the quadtree-based embedded coder, a new cost function for the best basis selection is adopted in SA-DWPT (shape adaptive discrete wavelet packet transform). The significance probability of wavelet coefficient...

Noncasual Markov (or energy-based) models are widely used in early vision applications for the representation of images in high-dimensional inverse problems. Due to their noncausal nature, these models generally lead to iterative inference algorithms that are computationally demanding. In this paper, we consider a special class of nonlinear Markov models which allow one to circumvent this drawb...

We give a closed-form expression for the average number of n-dimensional quadtree nodes (“pieces” or “blocks”) required by an n-dimensional hyperrectangle aligned with the axes. Our formula includes as special cases the formulae of previous efforts for two-dimensional spaces [8]. It also agrees with theoretical and empirical results that the number of blocks depends on the hypersurface of the h...

We present GeoSRS, a hybrid recommender system for a popular locationbased social network (LBSN), in which users are able to write short reviews on the places of interest they visit. Using state-of-the-art text mining techniques, our system recommends locations to users using as source the whole set of text reviews in addition to their geographical location. To evaluate our system, we have coll...

High Efficiency Video Coding is a new video coding standard after H.264/AVC. By introducing a flexible coding unit, which can be recursively divided from 64×64 to 8×8 blocks in a Quadtree-Structure, HEVC achieves significantly higher coding efficiency than the previous standards. With the flexible CU structure, HEVC can effectively adapt to highly varying contents with a smaller CU or to flat c...

This paper describes a new fast hybrid adaptive grid generation technique for arbitrary twodimensional domains. This technique is based on a Cartesian background grid with square elements and quadtree decomposition. A new algorithm is introduced for the distribution of boundary points based on the curvature of the domain boundaries. The quadtree decomposition is governed either by the distribut...