This paper presents a robust algorithm for video sequences stabilization. Motion estimation is achieved using block motion vectors. In this way the same motion estimator of mpeg encoder can be used. The simple use of block motion vectors can give unreliable global motion vectors and so elaborations are done to make the algorithm robust.
We present a collection of methods and algorithms able to deal with high dynamic ranges of real pictures acquired by digital engines e.g., charge-coupled device (CCD/CMOS) cameras. An accurate image acquisition can be challenging under difficult light conditions. A few techniques that overcome dynamic range limitations problems are reported. The presented methods allow the recovery of the original radiance values of the final 8-bit-depth image starting from differently exposed pictures. This allows the capture of both low-and highlight details by merging the various pictures into a single map, thus providing a more faithful description of what the real world scene was. However, in order to be viewed on a common computer monitor, the map needs to be compressed and requantized while preserving the visibility of details. The main problem comes from the fact that the contrast of the radiance values is usually far greater than that of the display device. Various related techniques are reviewed and discussed.
This work presents an effective procedure devised to implement the time discontinuous Galerkin method for linear dynamics. In particular, the method with piecewise linear time interpolation is considered. The procedure is based on a simple and low-cost iterative scheme, which is designed not as a mere solution algorithm, but rather as a method to generate improved approximations to the exact solution. The corrected solutions inherit the desired stability and dissipative properties from the target solution, while accuracy is improved by iterations. Indeed, no more than two iterations are shown to be needed. The resultant algorithm leads to remarkable computational savings and can be easily implemented into existing finite element codes. Numerical tests confirm that the present procedure possesses many attractive features for applications to dynamic analysis. IntroductionThis paper deals with time integration methods for linear dynamics based on the following first order form of the semidiscrete equations _ y yðtÞ ¼ ByðtÞ þ qðtÞ; t 2 0; t f À Ã ; ð1Þobtained by settingandwhere a superposed dot denotes differentiation with respect to time t, M is the mass matrix, C is the damping matrix, K is the stiffness matrix, f is the prescribed load vector, u and v are the unknown displacement and velocity vectors, u 0 and v 0 are the prescribed initial displacement and velocity vectors. The size of vectors u and v is denoted by n eq , while the size of y is N ¼ 2n eq . The above equations are generally derived from standard finite element semidiscretizations and only a few low-frequency modes are accurate approximations of the underlying continuous problem [1]. Thus, the quality of simulations depends crucially on the accuracy properties of the time integration method in the low-frequency modes, as well as on the dissipative properties in the highfrequency ones. The Time Discontinuous Galerkin (TDG) method possesses these desirable properties and has been successfully applied to linear dynamics (see for example [2][3][4][5][6][7][8][9][10][11][12]). However, despite its good properties, it typically leads to systems of coupled equations which are larger than the original system, so that standard implementations turn out to be very demanding for both storage and computational work, as already pointed out in [8]. Thus, developing effective implementations plays a key role in the practical application of the method. Indeed, computational efficiency is crucial for all higher-order methods and has been the focus of intensive research in the last decades (see for example [13][14][15][16][17][18][19][20][21][22][23][24]). An attractive methodology to obtain dissipative higher-order algorithms was early proposed by Nørsett [13] and recently reviewed by Mancuso and Ubertini [14]. Although these algorithms are not optimal from the point of view of accuracy, they can be actually considered as optimal from the point of view of computational efficiency. An attempt to devise low-cost higher-order dissipative methods by improving accuracy ...
This paper focuses on the formulation and implementation of explicit predictor} multicorrector Time Discontinuous Galerkin methods for linear structural dynamics. The formulation of the schemes is based on piecewise linear functions in time that approximate displacements and momenta. Both the predictors and correctors are designed to inherit third order accuracy from the exact parent implicit Time Discontinuous Galerkin method. Moreover, they are endowed with large stability limits and controllable numerical dissipation by means of an algorithmic parameter. Thereby, the resulting algorithms appear to be competitive with standard explicit algorithms for structural dynamics. Representative numerical simulations are presented illustrating the performance of the proposed numerical schemes and con"rming the analytical results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.