Browsing by Author "Guesalaga, AR"

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    Magnetic resonance imaging for nondestructive analysis of wine grapes
    (AMER CHEMICAL SOC, 2004) Andaur, JE; Guesalaga, AR; Agosin, EE; Guarini, MW; Irarrazaval, P
    Magnetic resonance imaging (MRI) was used to study the growth and ripening of grape berries for three varieties. The results show that this technique allows the visualization of internal characteristics of berries using noninvasive procedures in order to obtain the volume and degreesBrix distribution within a cluster. Samples of Cabernet Sauvignon, Carmenere, and Chardonnay varieties collected over the 2002 season were analyzed. Calibration models were developed to correlate soluble solids (degreesBrix) against spin-lattice relaxation time t(1) and spin-spin relaxation time t(2). The correlation of degreesBrix and t(1) was R-2 = 0.75 for Cabernet Sauvignon, R-2 = 0.8 for Carmenere, and R-2 = 0.65 for Chardonnay. In the case of t(2) the correlation was significantly lower. Reconstruction techniques for the three-dimensional representation of clusters were developed, allowing an interactive visualization of the bunches. The method also provides volume measurements of single berries and their distribution within the cluster with an accuracy of 3% and R-2 = 0.98. These results show the potential of MRI in the wine industry for both monitoring and research. Not only does it provide quantitative information about the berries such as Volume and degreesBrix distributions, but it can also be used to support the sampling procedures by providing a better cluster characterization.
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    Measuring physical properties of paper with an on-line visual sensor
    (1997) Guesalaga, AR; Cabezas, FM; Gottschalk, C
    Experimental results of a novel on-line paper shrinkage sensor are presented, showing a clear correlation with laboratory test indices such as elongation, breaking load and tensile energy absorption. Trials carried out in a paper machine producing sack paper also include a dynamic analysis of the effect of jet-to-wire ratio on paper shrinkage based on these measurements. The measurement is based on digital image processing techniques and provides a tool for instantaneous corrective control of physical variables during paper manufacture.
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    Robust estimation of 3D trajectories from a monocular image sequence
    (JOHN WILEY & SONS INC, 2002) Pang, CYC; Guesalaga, AR; Roda, VO
    This article describes a new method for object trajectory estimation that uses sequences of images taken from a monocular camera. The method integrates a Kalman filter to estimate the three-dimensional (3D) parameters of the optical system and a lineal projective model to determine 3D point coordinates projected on the retinal plane. It works with at least three distinctive points in the image, and they are updated with correlation methods. The result is an estimation of the rotation and translation parameters between successive images within the sequence and yield to the 3D coordinates of the points selected for correspondence. The scaling problem related to 3D reconstruction is tackled via a priori information of the objects being observed. The method is tested with synthetic images to evaluate its accuracy, and later, an interesting application in autonomous navigation is presented. (C) 2002 Wiley Periodicals, Inc.