11755901
Interactive mesh deformation with pseudo material effects
This paper presents a novel interactive mesh deformation method that can achieve various dynamic material effects, including elastic membrane and cloth effects. In our framework, a mesh is encoded by some differential quantities based on edge length and dihedral angle; and the deformation is formulated as a least square problem for preserving the edge length and dihedral angle via the differential quantities. In order to obtain anisotropic material effects, we further propose an edge-weighting scheme based on a user-specified vector field. To avoid specifying the local transformations, we set up an iterative scheme for solving the deformation. At last, several examples are presented to show that our approach can interactively generate visually pleasing deformations. Copyright © 2006 John Wiley & Sons, Ltd.
4392406
Synthesis and rendering of bidirectional texture functions on arbitrary surfaces
The bidirectional texture function (BTF) is a 6D function that describes the appearance of a real-world surface as a function of lighting and viewing directions. The BTF can model the fine-scale shadows, occlusions, and specularities caused by surface mesostructures. We present algorithms for efficient synthesis of BTFs on arbitrary surfaces and for hardware-accelerated rendering. For both synthesis and rendering, a main challenge is handling the large amount of data in a BTF sample. To addresses this challenge, we approximate the BTF sample by a small number of 4D point appearance functions (PAFs) multiplied by 2D geometry maps. The geometry maps and PAFs lead to efficient synthesis and fast rendering of BTFs on arbitrary surfaces. For synthesis, a surface BTF can be generated by applying a texton-based synthesis algorithm to a small set of 2D geometry maps while leaving the companion 4D PAFs untouched. As for rendering, a surface BTF synthesized using geometry maps is well-suited for leveraging the programmable vertex and pixel shaders on the graphics hardware. We present a real-time BTF rendering algorithm that runs at the speed of about 30 frames/second on a mid-level PC with an ATI Radeon 8500 graphics card. We demonstrate the effectiveness of our synthesis and rendering algorithms using both real and synthetic BTF samples.
5155570
Low-power repeater insertion with both delay and slew rate constraints
In this paper, a novel repeater insertion algorithm is presented to minimize the power dissipation of interconnect trees under given timing budgets and slew rate constraints. In contrast to traditional bottom-up dynamic programming approaches, the proposed algorithm combines a Lagrangian relaxation framework and a graph-based search method to derive possible solutions in a top-down fashion. As a result, it is capable of analyzing repeater slew rates efficiently. In addition, our scheme incorporates accurate circuit models and is therefore able to capture the precise delay and slew rate information, leading to high-quality interconnect designs. We have applied our scheme to interconnects of different topologies and various timing and slew rate constraints. Experimental results demonstrate the effectiveness of our approach in comparison with previous low-power repeater insertion schemes. Under tight timing constraints, our scheme can always derive repeater insertion solutions that meet both delay and slew rate requirements, whereas other schemes often fail. Under loose timing constraints, our algorithm achieves up to a 23% average power dissipation reduction for different interconnects specifications with shorter runtimes
792291
Variable grouping in multivariate time series via correlation
The decomposition of high-dimensional multivariate time series (MTS) into a number of low-dimensional MTS is a useful but challenging task because the number of possible dependencies between variables is likely to be huge. This paper is about a systematic study of the "variable groupings" problem in MTS. In particular, we investigate different methods of utilizing the information regarding correlations among MTS variables. This type of method does not appear to have been studied before. In all, 15 methods are suggested and applied to six datasets where there are identifiable mixed groupings of MTS variables. This paper describes the general methodology, reports extensive experimental results, and concludes with useful insights on the strength and weakness of this type of grouping method.
2596761
Variance-constrained control for uncertain stochastic systems with missing measurements
In this paper, we are concerned with a new control problem for uncertain discrete-time stochastic systems with missing measurements. The parameter uncertainties are allowed to be norm-bounded and enter into the state matrix. The system measurements may be unavailable (i.e., missing data) at any sample time, and the probability of the occurrence of missing data is assumed to be known. The purpose of this problem is to design an output feedback controller such that, for all admissible parameter uncertainties and all possible incomplete observations, the system state of the closed-loop system is mean square bounded, and the steady-state variance of each state is not more than the individual prescribed upper bound. We show that the addressed problem can be solved by means of algebraic matrix inequalities. The explicit expression of the desired robust controllers is derived in terms of some free parameters, which may be exploited to achieve further performance requirements. An illustrative numerical example is provided to demonstrate the usefulness and flexibility of the proposed design approach.
18361624
A new approach to retrieve video by example video clip
The similarity measure between video clips is a key issue in video retrieval. In the developing of our video retrieval system, we propose a new video similarity model. In contrast to existing algorithms, it proposes many influencing factors, such as order factor, speed factor, disturbance factor, etc, based on the subjective visual judgement of human. So this algorithm embodies the degree of similarity completely and systematically. On the other hand, it has resolution adaptation because it can be applied to every level of video structure. In the retrieval system, it can be used to process video query by example clip. This paper introduces it in detail and presents experiment results at the end of the paper.
9148979
Face detection using spectral histograms and SVMs
We present a face detection method using spectral histograms and support vector machines (SVMs). Each image window is represented by its spectral histogram, which is a feature vector consisting of histograms of filtered images. Using statistical sampling, we show systematically the representation groups face images together; in comparison, commonly used representations often do not exhibit this necessary and desirable property. By using an SVM trained on a set of 4500 face and 8000 nonface images, we obtain a robust classifying function for face and nonface patterns. With an effective illumination-correction algorithm, our system reliably discriminates face and nonface patterns in images under different kinds of conditions. Our method on two commonly used data sets give the best performance among recent face-detection ones. We attribute the high performance to the desirable properties of the spectral histogram representation and good generalization of SVMs. Several further improvements in computation time and in performance are discussed.