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Publications

Publications by António Ribeiro Sousa

2012

Blind navigation support system based on Microsoft Kinect

Authors
Filipe, V; Fernandes, F; Fernandes, H; Sousa, A; Paredes, H; Barroso, J;

Publication
PROCEEDINGS OF THE 4TH INTERNATIONAL CONFERENCE ON SOFTWARE DEVELOPMENT FOR ENHANCING ACCESSIBILITY AND FIGHTING INFO-EXCLUSION (DSAI 2012)

Abstract
This paper presents a system which extends the use of the traditional white cane by the blind for navigation purposes in indoor environments. Depth data of the scene in front of the user is acquired using the Microsoft Kinect sensor which is then mapped into a pattern representation. Using neural networks, the proposed system uses this information to extract relevant features from the scene, enabling the detection of possible obstacles along the way. The results show that the neural network is able to correctly classify the type of pattern presented as input.

2011

Processing discontinuous displacement fields by a spatio-temporal derivative technique

Authors
Sousa, AMR; Xavier, J; Morais, JJL; Filipe, VMJ; Vaz, M;

Publication
OPTICS AND LASERS IN ENGINEERING

Abstract
In this paper, a digital image correlation (DIC) method coupling cross-correlation with spatio-temporal differential techniques was proposed for assessing discontinuous displacement fields. The accuracy and robustness of the algorithm was assessed on a set of numerical tests by processing computer generated speckled-pattern images. Fracture mechanical tests in mode I were considered, in which both in-plane and out-of-plane rigid-body movements were taken into account. The ability for recovering the analytical asymptotic displacement field in mode I was analysed, and stress intensity factor, crack opening displacement and crack tip location were used as quantitative parameters for validation purposes. Throughout these tests, the results obtained with the proposed method were systematically compared to the ones from Aramis DIC-2D commercial code. Globally, the results computed from both methods are in good agreement with reference values. However, due to the high spatial resolution (point-wise characteristic), a better matching of the displacements in the neighbour of discontinuities could be obtained by the proposed method.

2008

Fast and straightforward method to estimate sub-pixel level displacement field

Authors
Sousa, A; Morais, J; Filipe, V; Jesus, A; Vaz, MAP;

Publication
COMPUTATIONAL VISION AND MEDICAL IMAGING PROCESSING

Abstract
This paper presents a fast and straightforward method to assess displacement fields on the surface of a planar specimen with sub-pixel resolution. First, pixel level displacements are obtained by cross correlation (CC) of two consecutive images, used as the image similarity measure. Next, sub-pixel displacement information is calculated from the CC coefficients matrix using a similarity interpolation method. Finally, sub-pixel estimation error cancellation is performed. Several experiments were conducted to validate the proposed method effectiveness, applied to chestnuts compression test for quality control purposes.

2022

Exploratory approach for automatic detection of vine rows in terrace vineyards

Authors
Figueiredo, N; Pádua, L; Cunha, A; Sousa, JJ; Sousa, AMR;

Publication
CENTERIS 2022 - International Conference on ENTERprise Information Systems / ProjMAN - International Conference on Project MANagement / HCist - International Conference on Health and Social Care Information Systems and Technologies 2022, Hybrid Event / Lisbon, Portugal, November 9-11, 2022.

Abstract

2022

Acacia dealbata classification from aerial imagery acquired using unmanned aerial vehicles

Authors
Pinto, J; Sousa, AMR; Sousa, JJ; Peres, E; Pádua, L;

Publication
CENTERIS 2022 - International Conference on ENTERprise Information Systems / ProjMAN - International Conference on Project MANagement / HCist - International Conference on Health and Social Care Information Systems and Technologies 2022, Hybrid Event / Lisbon, Portugal, November 9-11, 2022.

Abstract

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