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Barcelona, Spain

Puig-Centelles A.,Starlab Barcelona | Ramos F.,Jaume I University | Ripolles O.,Neuroelectrics | Chover M.,Jaume I University | Sbert M.,University of Girona
The Scientific World Journal | Year: 2014

Modeling and rendering realistic ocean scenes have been thoroughly investigated for many years. Its appearance has been studied and it is possible to find very detailed simulations where a high degree of realism is achieved. Nevertheless, among the solutions to ocean rendering, real-time management of the huge heightmaps that are necessary for rendering an ocean scene is still not solved. We propose a new technique for simulating the ocean surface on GPU. This technique is capable of offering view-dependent approximations of the mesh while maintaining coherence among the extracted approximations. This feature is very important as most solutions previously presented must retessellate from the initial mesh. Our solution is able to use the latest extracted approximation when refining or coarsening the mesh. © 2014 Anna Puig-Centelles et al.

Puig-Centelles A.,Starlab Barcelona | Varley P.A.C.,Jaume I University | Ripolles O.,Neuroelectrics Barcelona | Chover M.,Jaume I University
Multimedia Tools and Applications | Year: 2014

Nowadays, applications such as scientific simulations, virtual reality or computer games are increasing the detail of their environments with the aim of offering more realism. Terrain is a very important element in these outdoor scenarios. Artists are currently requiring a higher level of customization. In this sense, the objective of the work presented in this paper is to provide the final user with an easyto-use terrain generation application. More precisely, our aim is to ease the creation of islands. We propose a sketching solution which, combined with a simple terrain algorithm, is capable of suiting the user needs. The application is composed of two windows, which offer 2D and 3D representations of the terrain respectively. These windows are sufficient for providing the user with an interactive feedback about the island that is being designed. We try to show that relatively simple algorithms can be combined and improved to provide successful results. © Springer Science+Business Media, LLC 2012.

Llobera J.,University of Barcelona | Spanlang B.,University of Barcelona | Spanlang B.,Polytechnic University of Catalonia | Ruffini G.,Starlab Barcelona | And 3 more authors.
ACM Transactions on Applied Perception | Year: 2010

An experiment was carried out to examine the impact on electrodermal activity of people when approached by groups of one or four virtual characters at varying distances. It was premised on the basis of proxemics theory that the closer the approach of the virtual characters to the participant, the greater the level of physiological arousal. Physiological arousal was measured by the number of skin conductance responses within a short time period after the approach, and the maximum change in skin conductance level 5 s after the approach. The virtual characters were each either female or a cylinder of human size, and one or four characters approached each subject a total of 12 times. Twelve male subjects were recruited for the experiment. The results suggest that the number of skin conductance responses after the approach and the change in skin conductance level increased the closer the virtual characters approached toward the participants. Moreover, these response variables were inversely correlated with the number of visits, showing a typical adaptation effect. There was some evidence to suggest that the number of characters who simultaneously approached (one or four) was positively associated with the responses. Surprisingly there was no evidence of a difference in response between the humanoid characters and cylinders on the basis of this physiological data. It is suggested that the similarity in this quantitative arousal response to virtual characters and virtual objects might mask a profound difference in qualitative response, an interpretation supported by questionnaire and interview results. Overall the experiment supported the premise that people exhibit heightened physiological arousal the closer they are approached by virtual characters. © 2010 ACM.

Egido A.,Starlab Barcelona | Caparrini M.,Starlab Barcelona | Ruffini G.,Starlab Barcelona | Paloscia S.,Institute for Applied Physics IFAC | And 4 more authors.
Remote Sensing | Year: 2012

The use of Global Navigation Satellite Systems (GNSS) signals for remote sensing applications, generally referred to as GNSS-Reflectometry (GNSS-R), is gaining increasing interest among the scientific community as a remote sensing tool for land applications. This paper describes a long term experimental campaign in which an extensive dataset of GNSS-R polarimetric measurements was acquired over a crop field from a ground-based stationary platform. Ground truth ancillary data were also continuously recorded during the whole experimental campaign. The duration of the campaign allowed to cover a full crop growing season, and as a consequence of seasonal rains on the experimental area, data could be recorded over a wide variety of soil conditions. This enabled a study on the effects of different land bio-geophysical parameters on GNSS scattered signals. It is shown that significant power variations in the measured GNSS reflected signals can be detected for different soil moisture and vegetation development conditions. In this work we also propose a technique based on the combination of the reflected signal's polarizations in order to improve the integrity of the observables with respect to nuisance parameters such as soil roughness. © 2012 by the authors.

Merlet I.,French Institute of Health and Medical Research | Merlet I.,University of Rennes 1 | Birot G.,French Institute of Health and Medical Research | Birot G.,University of Rennes 1 | And 9 more authors.
PLoS ONE | Year: 2013

Both biophysical and neurophysiological aspects need to be considered to assess the impact of electric fields induced by transcranial current stimulation (tCS) on the cerebral cortex and the subsequent effects occurring on scalp EEG. The objective of this work was to elaborate a global model allowing for the simulation of scalp EEG signals under tCS. In our integrated modeling approach, realistic meshes of the head tissues and of the stimulation electrodes were first built to map the generated electric field distribution on the cortical surface. Secondly, source activities at various cortical macro-regions were generated by means of a computational model of neuronal populations. The model parameters were adjusted so that populations generated an oscillating activity around 10 Hz resembling typical EEG alpha activity. In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations. Lastly, EEG under both spontaneous and tACS-stimulated (transcranial sinunoidal tCS from 4 to 16 Hz) brain activity was simulated at the level of scalp electrodes by solving the forward problem in the aforementioned realistic head model. Under the 10 Hz-tACS condition, a significant increase in alpha power occurred in simulated scalp EEG signals as compared to the no-stimulation condition. This increase involved most channels bilaterally, was more pronounced on posterior electrodes and was only significant for tACS frequencies from 8 to 12 Hz. The immediate effects of tACS in the model agreed with the post-tACS results previously reported in real subjects. Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency. This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations. © 2013 Merlet et al.

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