ABSTRACT In this paper, we propose an efficient and stable animation and rendering method for complex mass‐spring‐based cloth model for interactive applications. Although the mass‐spring model can be easily constructed and simulated, it is well known that the model suffers from the instability problem. The method proposed in this paper employs the harmonic oscillation model and analytically integrates the force for better stability and accuracy while keeping the integration scheme still explicit. As the integration scheme is explicit, the method can be easily parallelized, and the performance improvement can be easily obtained by exploiting the parallelism in the graphics processing unit. For the realistic representation of virtual clothes, we also proposed an efficient and effective rendering method for woven surfaces on the basis of alternating anisotropic reflectance and microfacet distribution function rotation. Copyright © 2012 John Wiley & Sons, Ltd.

Scalable video coding (SVC) has found more and more applications in a variety of the adaptive network streaming and the terminal. In the current SVC, an exhaustive search technique is employed to select the best coding mode for each macro block. This technique achieves the optimal trade-off between the bit-rate and distortion, but it results in extremely large encoding time which obstructs it from practical use. In this paper, we propose a fast mode decision algorithm for inter frame coding for spatial and coarse grain signal to noise ratio (SNR) scalability. In the proposed method, we predict the enhancement layer mode using both collocated macro block and its neighboring block mode in the base layer. The proposed method can achieve the time saving up to 78 percent in spatial scalability and 35 percent in coarse grain quality scalability (CGS) with the negligible loss of quality and increment in bit rate.

A fast intra mode determination algorithm based on the macro-block (MB) tracking scheme and rate-distortion (RD) cost is proposed for inter-frames in the H.264/AVC video standard. In addition to the inter mode search procedure with variable block size, an intra mode search causes a significant increase in the complexity and computational load for an inter frame. To reduce the computational load of the intra mode search at the inter frame, the rate-distortion (RD) cost of the tracked MB for the current MB are used and we propose adaptive thresholding algorithms for skipping the intra mode search. For the IPPP sequence type, the overall encoding time can be reduced up to 52% through comparative analysis of experimental results with JM reference software.

A fast inter-mode determination algorithm based on the macro-block (MB) tracking scheme and rate-distortion (RD) cost is proposed for the H.264/AVC video standard in which residual prediction is composed of intra-modes and inter-modes. In addition to intra-mode prediction, 8 block types exist for the best coding gain based on rate-distortion (RD) optimization in the inter-mode prediction. This scheme gives rise to exhaustive computations (search) in the coding procedure. To reduce the computational load of the inter-mode search at the inter-frame, we propose a new inter-mode determination algorithm based on the rate-distortion (RD) cost of the neighborhood MB that is tracked for the current MB in the previous frame. Based on the MB tracking scheme, an efficient sequential mode search approach is presented. We verify the performance of the proposed scheme through comparative analysis of experimental results using JM reference software.

Block motion estimation with full search is computationally complex. To reduce this complexity, different methods have been proposed, including partial distortion, which can reduce the computational complexity with no loss of image quality. We propose a distortion-based partial distortion search (DPDS) based on the magnitude of distortion and adaptive update of the matching order. We calculate absolute differences for all pixels in the predicted block point. Pixels are then sorted by the amount of distortion in a descending order for the matching process, which produces a scanning map. The sum of the absolute differences (SAD) of other candidate positions is then computed from this matching order. We also use an update of the scanning map by checking the increase in the number of absolute differences for the SAD value. The proposed DPDS algorithm improves the computational efficiency, compared with the original PDS scheme, because the accumulated value of the absolute pixel differences can rapidly reach the current minimum SAD value. The proposed algorithm is 4-13 times faster than the full search method with the same visual quality.

We propose a simple fast block-matching algorithm (BMA) based on the direction of the predicted motion vector called directional & adaptive diamond search by adaptive pattern switching (DADS-APS). The proposal method has two sequential search steps, including 1) an initial search, and 2) a refinement search for the local area. Adaptive pattern switching (APS) is proposed for the initial search and a unit-size rood pattern is used for the refinement. The initial search step consists of pattern size determination and selection of a pattern shape. We use an adaptive pattern size that is adjusted by the amount of motion. This method is superior to a fixed-pattern size algorithm, regardless of the amount of motion. In video sequences, each motion has a unique direction. using this property, we use adaptive pattern switching between ARPS and DADS. APS considers the motion direction so we can easily and correctly find the minimal matching error (MME) point with less error distortion. APS can thus reduce the number of poorly related search points. Analysis shows that DADS-APS exhibits good PSNR performance and the average number of search points compares favorably with other methods.

We propose a fast inter-mode prediction and decision algorithm based on a contextual information for the P-slices in the H.264/AVC video standard. In the H.264/AVC standard, motion estimation part is composed of intra-modes and inter-modes. In the inter-mode prediction, 7 block types exist to get the best coding gain based on rate-distortion (R-D) optimization. This scheme gives rise to an exhaustive computation (search) in the coding procedure. To overcome this computational exhaustiveness, an improved technique is suggested by using the contextual prediction. Also, we will verify the performance of the proposed scheme through the analysis of some experimental results.

In this paper, we propose a differential structure of subpixels which are interpolated from integer pixels using ntab linear FIR filters. The generation and management of sub-pixels are a very serious problem in high-definition H.264 video encoding. Since the amount of sub-pixels in H.264 encoding is about 16 times larger than that of integer pixels, H.264 encoder needs very high speed memory access for realtime encoding of high-definition video. In order to avoid the sub-pixel problem, we estimate the distortion value for a motion estimation of sub-pixel resolution by using the nonlinear combination of the distortion value derived from a motion estimation of related integer pixel, based on the proposed differential structure. Simulation results show that the proposed mathematical properties are valid by the sub-pixel motion estimation based on the proposed mathematical analysis. It also shows that the proposed sub-pixel motion estimation is so effective that the encoding speed is dramatically increased without a considerable depression of video quality.