Alejandro César Frery

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Remote sensing data, and radar data in particular, have become an essential tool for enviromental studies. Many airborne polarimetric sensors are currently operational, and many more will be available in the near future including spaceborne platforms. The signal-to-noise ratio of this kind of imagery is lower than that of optical information requiring,(More)
Wireless sensor networks produce a large amount of data that needs to be processed, delivered, and assessed according to the application objectives. The way these data are manipulated by the sensor nodes is a fundamental issue. Information fusion arises as a response to process data gathered by sensor nodes and benefits from their processing capability. By(More)
—This paper presents the use of a new distribution for fully polarimetric image classification. Several classification strategies are compared in order to assess the importance of a careful statistical modeling of the data and the complementary nature of the information provided by different frequencies. Spatial context, which is relevant in order to obtain(More)
—Images obtained with coherent illumination, as is the case of sonar, ultrasound-B, laser and Synthetic Aperture Radar – SAR, are affected by speckle noise which reduces the ability to extract information from the data. Specialized techniques are required to deal with such imagery, which has been modeled by the G 0 distribution and under which regions with(More)
This paper presents adjusted profile likelihoods for α, the roughness parameter of G 0 A (α, γ, L) distribution. This distribution has been widely used in the modelling of data corrupted by speckle noise (SAR images). We focus on point estimation and on signalized likelihood ratio tests. As far as point estimation is concerned, the numerical evidence(More)
The advances of Virtual Reality techniques have aided Virtual Environments become more dynamic and more realistic. The need to turn such systems closer to user's reality has led to environments that both track users actions and are capable of adapting to the users' profile. This article presents an infrastructure for managing virtual reality components,(More)
Complex networks can model the structure and dynamics of different types of systems. It has been shown that they are characterized by a set of measures. In this work, we evaluate the variability of complex networks measures face to perturbations and, for this purpose, we impose controlled perturbations and quantify their effect. We analyze theoretical(More)