Estimating the motion of an underwater robot from a monocular image sequence

When underwater vehicles perform navigation close to the ocean floor, computer vision techniques can be applied to obtain quite accurate motion estimates. The most crucial step in the vision-based estimation of the vehicle motion consists on detecting matchings between image pairs. Here we propose the extensive use of texture analysis as a tool to ameliorate the correspondence problem in underwater images. Once a robust set of correspondences has been found, the three-dimensional motion of the vehicle can be computed with respect to the bed of the sea. Finally, motion estimates allow the construction of a map that could aid to the navigation of the robot

A Motion compensated filtering approach to remove sunlight flicker in shallow water images

A common problem in video surveys in very shallow waters is the presence of strong light fluctuations, due to sun light refraction. Refracted sunlight casts fast moving patterns, which can significantly degrade the quality of the acquired data. Motivated by the growing need to improve the quality of shallow water imagery, we propose a method to remove sunlight patterns in video sequences. The method exploits the fact that video sequences allow several observations of the same area of the sea floor, over time. It is based on computing the image difference between a given reference frame and the temporal median of a registered set of neighboring images. A key observation is that this difference will have two components with separable spectral content. One is related to the illumination field (lower spatial frequencies) and the other to the registration error (higher frequencies). The illumination field, recovered by lowpass filtering, is used to correct the reference image. In addition to removing the sunflickering patterns, an important advantage of the approach is the ability to preserve the sharpness in corrected image, even in the presence of registration inaccuracies. The effectiveness of the method is illustrated in image sets acquired under strong camera motion containing non-rigid benthic structures. The results testify the good performance and generality of the approach

Proposal of a parallel architecture for a motion detection algorithm

This paper proposes a parallel architecture for estimation of the motion of an underwater robot. It is well known that image processing requires a huge amount of computation, mainly at low-level processing where the algorithms are dealing with a great number of data. In a motion estimation algorithm, correspondences between two images have to be solved at the low level. In the underwater imaging, normalised correlation can be a solution in the presence of non-uniform illumination. Due to its regular processing scheme, parallel implementation of the correspondence problem can be an adequate approach to reduce the computation time. Taking into consideration the complexity of the normalised correlation criteria, a new approach using parallel organisation of every processor from the architecture is proposed

Recovering Euclidean deformable models from stereo-motion

In this paper we present a novel structure from motion (SfM) approach able to infer 3D deformable models from uncalibrated stereo images. Using a stereo setup dramatically improves the 3D model estimation when the observed 3D shape is mostly deforming without undergoing strong rigid motion. Our approach first calibrates the stereo system automatically and then computes a single metric rigid structure for each frame. Afterwards, these 3D shapes are aligned to a reference view using a RANSAC method in order to compute the mean shape of the object and to select the subset of points on the object which have remained rigid throughout the sequence without deforming. The selected rigid points are then used to compute frame-wise shape registration and to extract the motion parameters robustly from frame to frame. Finally, all this information is used in a global optimization stage with bundle adjustment which allows to refine the frame-wise initial solution and also to recover the non-rigid 3D model. We show results on synthetic and real data that prove the performance of the proposed method even when there is no rigid motion in the original sequence

Online Robust 3D Mapping Using Structure from Motion Cues

This paper presents a complete solution for creating accurate 3D textured models from monocular video sequences. The methods are developed within the framework of sequential structure from motion, where a 3D model of the environment is maintained and updated as new visual information becomes available. The camera position is recovered by directly associating the 3D scene model with local image observations. Compared to standard structure from motion techniques, this approach decreases the error accumulation while increasing the robustness to scene occlusions and feature association failures. The obtained 3D information is used to generate high quality, composite visual maps of the scene (mosaics). The visual maps are used to create texture-mapped, realistic views of the scene

Enhanced Model Selection for motion segmentation

In this paper a novel rank estimation technique for trajectories motion segmentation within the Local Subspace Affinity (LSA) framework is presented. This technique, called Enhanced Model Selection (EMS), is based on the relationship between the estimated rank of the trajectory matrix and the affinity matrix built by LSA. The results on synthetic and real data show that without any a priori knowledge, EMS automatically provides an accurate and robust rank estimation, improving the accuracy of the final motion segmentation

Rank estimation of trajectory matrix in motion segmentation

A novel technique for estimating the rank of the trajectory matrix in the local subspace affinity (LSA) motion segmentation framework is presented. This new rank estimation is based on the relationship between the estimated rank of the trajectory matrix and the affinity matrix built with LSA. The result is an enhanced model selection technique for trajectory matrix rank estimation by which it is possible to automate LSA, without requiring any a priori knowledge, and to improve the final segmentation

Predictive motion control of a mirosot mobile robot

This paper discusses predictive motion control of a MiRoSoT robot. The dynamic model of the robot is deduced by taking into account the whole process - robot, vision, control and transmission systems. Based on the obtained dynamic model, an integrated predictive control algorithm is proposed to position precisely with either stationary or moving obstacle avoidance. This objective is achieved automatically by introducing distant constraints into the open-loop optimization of control inputs. Simulation results demonstrate the feasibility of such control strategy for the deduced dynamic model

Attitude in students of Health Sciences toward scientific knowledge

Educating health professionals implies the challenge of creating and developing an inquiring mind, ready to be in a state of permanent questioning. For this purpose, it is fundamental to generate a positive attitude toward the generation of knowledge and science. Objective: to determine the attitude toward science and the scientific method in undergraduate students of health sciences. Materials and methods: a cross-sectional study was made by applying a self-administered survey, excluding those who were transferred from other universities and repeated. The attitude toward science and the scientific method were valued using the scale validated and published by Hren, which contains three domains: value of scientific knowledge, value of scientific methodology, and value of science for health professions. Results: 362 students were included, 86,6% of them graded the attitude toward scientific knowledge above 135 points, neutral scale value. Similar scores were registered in the domains value of scientific knowlede for the human dimension of the students and value of science for health professions. 91,4% of the students graded the value of scientific methodology below 48 points. Conclusions: the favorable attitude of the students can be explained by the contact that they have with the scientific method since the beginning of their studies and its concordance with the evolution of science. The domain value of scientific methodology obtained the lowest grade on the part of the students, which could be related to the lack of knowledge about scientific methodology.

La medida de la eficacia docente. Descripci??n y aplicaci??n del Minnesota Teacher Attitude Inventory : un instrumento predictor

Ofrecer una panor??mica que pretende incluir el fundamento de la evaluaci??n en general, su concreci??n en el ??mbito de la evaluaci??n del docente, es decir, de su eficacia describiendo modalidades e instrumentos de evaluaci??n y sus agentes. Analizar una de esas modalidades: Minnesota Teacher Attitude Inventory a partir de una experiencia concreta. Hip??tesis: A) La clasificaci??n ordinal atendiendo a los promedios obtenidos en las calificaciones de las asignaturas cursadas durante la carrera, no guardan correlaci??n significativa con las puntuaciones del Minnesota Teacher Attitude Inventory. B) Las calificaciones en la asignatura de Did??ctica obtenidas por los alumnos de segundo curso guardan correlaci??n con las puntuaciones en el MTAI. C) Las actitudes de los estudiantes de Magisterio frente a la Educaci??n, despu??s de haber realizado su per??odo largo de pr??cticas docentes -3 meses-, se modifican negativamente. Alumnos de los tres cursos de las Escuelas de Formaci??n del Profesorado de EGB de Barcelona y Tarragona (oficiales) y Blanquerna de Barcelona (no oficial), durante el mes de mayo de 1979. Definidos los planteamientos te??ricos se aplica el MTAI despu??s de haberle hecho unas adaptaciones formales para poderlo aplicar a nuestro contexto y confeccionar una hoja de respuestas m??s operativa y ??til para la correcci??n manual con plantilla. En base a unas hip??tesis y disponiendo de unos datos se analizan los resultados y se extraen las conclusiones pertinentes. Consultas personales, textos, documentos y revistas educativas. MTAI (mide las actitudes, prev?? las relaciones que se establecen en la clase y la satisfacci??n que el futuro educador obtendr?? de la Ense??anza como profesi??n). Tabulaci??n de los datos mediante puntuaciones medias globales, pol??gonos de frecuencias, correlaciones graduales y correlaciones lineales. Las puntuaciones obtenidas no se corresponden con las de los baremos americanos, la media en el baremo es de 59.5 y la de nuestros estudiantes apenas sobrepasa el 30. Hay una necesidad de adaptaciones y validaciones completas para pruebas de prestigio en otras ??reas geogr??ficas. El instrumento es ??til para servirse de ??l como referencia, a pesar de las deficiencias que implica la aplicaci??n directa e inmediata tras la traducci??n del original.

Antecedents of the attitude towards inter-group reconciliation in a setting of armed conflict

Resumen tomado de la publicación

Psychometric properties of the Spanish Adaptation of the School Attitude Assessment Survey-Revised

Resumen tomado de la publicaci??n

Adaptation of the Evidence-Based Practices Attitude Scale in Spanish child welfare professionals

Resumen tomado de la publicaci??n

Treatment of nonlinear optical properties due to large amplitude anharmonic vibrational motions: umbrella motion in NH3

A general reduced dimensionality finite field nuclear relaxation method for calculating vibrational nonlinear optical properties of molecules with large contributions due to anharmonic motions is introduced. In an initial application to the umbrella (inversion) motion of NH3 it is found that difficulties associated with a conventional single well treatment are overcome and that the particular definition of the inversion coordinate is not important. Future applications are described