Encontrados 5 documentos, a visualizar página 1 de 1
Efficient Optimization Algorithm for Space-Variant Mixture of Vector Fields
Nascimento, Jacinto C.; Barão, Miguel; Marques, Jorge S.; Lemos, João M.This paper presents a new algorithm for trajectory classifi- cation of human activities. The presented framework uses a mixture of parametric space-variant vector fields to describe pedestrian’s trajecto- ries. An advantage of the proposed method is that the vector fields are not constant and depend on the pedestrian’s localization. This means that the switching motion among vector fields may occur at any image...
Recursive bayesian identification of nonlinear autonomous systems
Simão, Tiago; Barão, Miguel; Marques, Jorge S.This paper concerns the recursive identification of nonlinear discrete-time systems for which the original equations of motion are not known. Since the true model structure is not available, we replace it with a generic nonlinear model. This generic model discretizes the state space into a finite grid and associates a set of velocity vectors to the nodes of the grid. The velocity vectors are then interpolated t...
Alignment of velocity fields for video surveillance
Marques, Jorge S.; Barão, Miguel; Lemos, João M.Velocity fields play an important role in surveillance since they describe typical motion behaviors of video objects (e.g., pedestrians) in the scene. This paper presents an algorithm for the alignment of velocity fields acquired by different cameras, at different time intervals, from different viewpoints. Velocity fields are aligned using a warping function which maps corresponding points and vectors in both f...
Alignment of velocity fields for video surveillance
Marques, Jorge S.; Barão, Miguel; Lemos, João M.Velocity fields play an important role in surveillance since they describe typical motion behaviors of video objects (e.g., pedestrians) in the scene. This paper presents an algorithm for the alignment of velocity fields acquired by different cameras, at different time intervals, from different viewpoints. Velocity fields are aligned using a warping function which maps corresponding points and vectors in both f...
Offline Bayesian Identification of Jump Markov Nonlinear Systems
Barão, Miguel; Marques, Jorge S.This paper presents a framework for the offline identification of nonlinear switched systems with unknown model structure. Given a set of sampled trajectories, and under the assumption that they were generated by switching among a number of models, we estimate a set of vector fields and a stochastic switching mechanism that best describes the observed data. The switching mechanism is described by a position dep...
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