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Cabeza Laguna, Rafael

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Cabeza Laguna

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Rafael

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    PublicationOpen Access
    Models for gaze tracking systems
    (Hindawi Publishing Corporation, 2007) Villanueva Larre, Arantxa; Cabeza Laguna, Rafael; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    One of the most confusing aspects that one meets when introducing oneself into gaze tracking technology is the wide variety, in terms of hardware equipment, of available systems that provide solutions to the same matter, that is, determining the point the subject is looking at. The calibration process permits generally adjusting nonintrusive trackers based on quite different hardware and image features to the subject. The negative aspect of this simple procedure is that it permits the system to work properly but at the expense of a lack of control over the intrinsic behavior of the tracker. The objective of the presented article is to overcome this obstacle to explore more deeply the elements of a video-oculographic system, that is, eye, camera, lighting, and so forth, from a purely mathematical and geometrical point of view. The main contribution is to find out the minimum number of hardware elements and image features that are needed to determine the point the subject is looking at. A model has been constructed based on pupil contour and multiple lighting, and successfully tested with real subjects. On the other hand, theoretical aspects of video-oculographic systems have been thoroughly reviewed in order to build a theoretical basis for further studies.
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    PublicationOpen Access
    Fisiopatología y técnicas de registro de los movimientos oculares
    (Gobierno de Navarra, 2009) Gila Useros, Luis; Villanueva Larre, Arantxa; Cabeza Laguna, Rafael; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    En el control de la motilidad ocular intervienen varios sistemas funcionales. Los reflejos vestíbulo-oculares y optocinéticos son respuestas automáticas para compensar los movimientos de la cabeza y del entorno visual y poder estabilizar la imagen retiniana sobre un determinado punto de fijación. Los movimientos sacádicos son rápidos desplazamientos de la fijación de un punto a otro del campo visual. Los movimientos de persecución lenta consisten en el seguimiento de estímulos móviles con la mirada. Finalmente, existen movimientos involuntarios de muy escasa amplitud que se producen durante el mantenimiento de la fijación. Cada modalidad funcional de movimiento depende de circuitos neuronales específicos que trabajan coordinadamente para codificar la contracción de los músculos oculomotores correspondiente a la posición adecuada en cada momento. Estos sistemas neuronales pueden verse alterados por múltiples procesos neurológicos de diferente naturaleza y localización dando lugar a una variada gama de trastornos oculomotores. Se revisan los aspectos más destacados de la fisiopatología y de los sistemas de registro de los movimientos oculares.
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    PublicationOpen Access
    Introducing I2Head database
    (ACM (Association for Computing Machinery), 2018) Martinikorena Aranburu, Ion; Cabeza Laguna, Rafael; Villanueva Larre, Arantxa; Porta Cuéllar, Sonia; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    I2Head database has been created with the aim to become an optimal reference for low cost gaze estimation. It exhibits the following outstanding characteristics: it takes into account key aspects of low resolution eye tracking technology; it combines images of users gazing at different grids of points from alternative positions with registers of user's head position and it provides calibration information of the camera and a simple 3D head model for each user. Hardware used to build the database includes a 6D magnetic sensor and a webcam. A careful calibration method between the sensor and the camera has been developed to guarantee the accuracy of the data. Different sessions have been recorded for each user including not only static head scenarios but also controlled displacements and even free head movements. The database is an outstanding framework to test both gaze estimation algorithms and head pose estimation methods.
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    PublicationOpen Access
    Differences in specific abdominal fat depots between metabolically healthy and unhealthy children with overweight/obesity: the role of cardiorespiratory fitness
    (Wiley, 2023) Cadenas-Sánchez, Cristina; Medrano Echeverría, María; Villanueva Larre, Arantxa; Cabeza Laguna, Rafael; Idoate, Fernando; Osés Recalde, Maddi; Rodríguez Vigil, Beatriz; Álvarez de Eulate, Natalia; Alberdi Aldasoro, Nerea; Ortega, Francisco B.; Labayen Goñi, Idoia; Ciencias de la Salud; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Institute of Smart Cities - ISC; Osasun Zientziak; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    Objectives: Fat depots localization has a critical role in the metabolic health status of adults. Nevertheless, whether that is also the case in children remains under- studied. Therefore, the aims of this study were: (i) to examine the differ-ences between metabolically healthy (MHO) and unhealthy (MUO) overweight/obesity phenotypes on specific abdominal fat depots, and (ii) to further explore whether cardiorespiratory fitness plays a major role in the differences between metabolic phenotypes among children with overweight/obesity. Methods: A total of 114 children with overweight/obesity (10.6 ±1.1 years, 62 girls) were included. Children were classified as MHO (n=68) or MUO. visceral (VAT), abdominal subcutaneous (ASAT), intermuscular abdominal (IMAAT), psoas, hepatic, pancreatic, and lumbar bone marrow adipose tissues were measured by magnetic resonance imaging. Cardiorespiratory fitness was assessed using the 20 m shuttle run test. Results: MHO children had lower VAT and ASAT contents and psoas fat fraction compared to MUO children (difference =12.4%– 25.8%, all p<0.035). MUO- unfit had more VAT and ASAT content than those MUO- fit and MHO- fit (difference =34.8%– 45.3%, all p<0.044). MUO- unfit shows also greater IMAAT fat fraction than those MUO- fit and MHO- fit peers (difference =16.4%– 13.9% respectively, all p≤0.001). In addition, MHO- unfit presented higher IMAAT fat fraction than MHO- fit (difference =13.4%, p<0.001). MUO- unfit presented higher psoas fat fraction than MHO- fit (difference =29.1%, p=0.008). Conclusions: VAT together with ASAT and psoas fat fraction, were lower in MHO than in MUO children. Further, we also observed that being fit, regardless of metabolic phenotype, has a protective role over the specific abdominal fat depots among children with overweight/obesity.
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    PublicationOpen Access
    SeTA: semiautomatic tool for annotation of eye tracking images
    (ACM, 2019) Larumbe Bergera, Andoni; Porta Cuéllar, Sonia; Cabeza Laguna, Rafael; Villanueva Larre, Arantxa; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    Availability of large scale tagged datasets is a must in the field of deep learning applied to the eye tracking challenge. In this paper, the potential of Supervised-Descent-Method (SDM) as a semiautomatic labelling tool for eye tracking images is shown. The objective of the paper is to evidence how the human effort needed for manually labelling large eye tracking datasets can be radically reduced by the use of cascaded regressors. Different applications are provided in the fields of high and low resolution systems. An iris/pupil center labelling is shown as example for low resolution images while a pupil contour points detection is demonstrated in high resolution. In both cases manual annotation requirements are drastically reduced.
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    PublicationOpen Access
    Effects of a family-based lifestyle intervention plus supervised exercise training on abdominal fat depots in children with overweight or obesity: a secondary analysis of a nonrandomized clinical trial
    (American Medical Association, 2022) Cadenas-Sánchez, Cristina; Cabeza Laguna, Rafael; Idoate, Fernando; Osés Recalde, Maddi; Medrano Echeverría, María; Villanueva Larre, Arantxa; Arenaza, Lide; Sanz Muñoz, Aritz; Ortega, Francisco B.; Ruiz, Jonatan R.; Labayen Goñi, Idoia; Ciencias de la Salud; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Institute of Smart Cities - ISC; Osasun Zientziak; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    Importance Excess abdominal fat is a major determinant in the development of insulin resistance and other metabolic disorders. Increased visceral adipose tissue (VAT) seems to precede the development of insulin resistance and is therefore a prime target of childhood lifestyle interventions aimed at preventing diabetes. OBJECTIVES To examine the effect of added exercise to a family-based lifestyle intervention program designed to reduce VAT plus subcutaneous (ASAT), intermuscular (IMAAT), and pancreatic (PAT) adipose tissue in children with overweight or obesity and to explore the effect of changes in VAT on insulin resistance. DESIGN, SETTING, AND PARTICIPANTS This 2-group, parallel-design clinical trial was conducted in Vitoria-Gasteiz, Spain. A total of 116 children with overweight or obesity participated and were assigned to a 22-week family-based lifestyle program (control group [n = 57]) or the same program plus an exercise intervention (exercise group [n = 59]). Data were collected between September 1, 2014, and June 30, 2017, and imaging processing for fat depot assessments and data analysis were performed between May 1, 2019, and February 12, 2021. INTERVENTIONS The compared interventions consisted of a family-based lifestyle and psychoeducation program (two 90-minute sessions per month) and the same program plus supervised exercise (three 90-minute sessions per week). MAIN OUTCOMES AND MEASURES The primary outcome of this study was the change in VAT between baseline and 22 weeks as estimated by magnetic resonance imaging. The secondary outcomes were changes in ASAT, IMAAT, and PAT. The effect of changes in VAT area on insulin resistance was also recorded. RESULTS The 116 participants included in the analysis (62 girls [53.4%]) had a mean (SD) age of 10.6 (1.1) years, and 67 (57.8%) presented with obesity. Significantly greater reductions were recorded for the exercise group in terms of reduction in VAT (−18.1% vs −8.5% for the control group; P = .004), ASAT (−9.9% vs −3.0%; P = .001), and IMAAT (−6.0% vs −2.6%; P = .02) fat fractions compared with the control group. Changes in VAT explained 87.6% of the improvement seen in insulin resistance (β = −0.102 [95% CI, −0.230 to −0.002]). CONCLUSIONS AND RELEVANCE These findings suggest that the addition of exercise to a lifestyle intervention program substantially enhanced the positive effects on abdominal fat depots in children with overweight or obesity. In addition, the reduction in VAT seemed to largely mediate the improvement of insulin sensitivity. These results highlight the importance of including exercise as part of lifestyle therapies aimed at treating childhood obesity and preventing the development of type 2 diabetes.
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    PublicationOpen Access
    Synthetic gaze data augmentation for improved user calibration
    (Springer, 2021) Garde Lecumberri, Gonzalo; Larumbe Bergera, Andoni; Porta Cuéllar, Sonia; Cabeza Laguna, Rafael; Villanueva Larre, Arantxa; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    In this paper, we focus on the calibration possibilitiesó of a deep learning based gaze estimation process applying transfer learning, comparing its performance when using a general dataset versus when using a gaze specific dataset in the pretrained model. Subject calibration has demonstrated to improve gaze accuracy in high performance eye trackers. Hence, we wonder about the potential of a deep learning gaze estimation model for subject calibration employing fine-tuning procedures. A pretrained Resnet-18 network, which has great performance in many computer vision tasks, is fine-tuned using user’s specific data in a few shot adaptive gaze estimation approach. We study the impact of pretraining a model with a synthetic dataset, U2Eyes, before addressing the gaze estimation calibration in a real dataset, I2Head. The results of the work show that the success of the individual calibration largely depends on the balance between fine-tuning and the standard supervised learning procedures and that using a gaze specific dataset to pretrain the model improves the accuracy when few images are available for calibration. This paper shows that calibration is feasible in low resolution scenarios providing outstanding accuracies below 1.5 ∘ ∘ of error.
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    PublicationOpen Access
    Attention to online channels across the path to purchase: an eye-tracking study
    (Elsevier, 2019) Cortiñas Ugalde, Mónica; Cabeza Laguna, Rafael; Chocarro Eguaras, Raquel; Villanueva Larre, Arantxa; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Enpresen Kudeaketa; Institute for Advanced Research in Business and Economics - INARBE; Ingeniería Eléctrica, Electrónica y de Comunicación; Gestión de Empresas
    Currently, consumers display what is known as omnichannel behavior: the combined use of digital and physical channels providing them with multiple points of contact with firms. We combine the stimulus-organism-response (S-O-R) model and visual attention theory to study how customers’ attention to digital channels varies across different purchasing tasks. We use eye-tracking techniques to observe attention in an experimental setting. The experimental design is composed of four purchasing tasks in four different product categories and measures the attention to the website and time spent on each task in addition to several control variables. The results show that shoppers attend to more areas of the website for purposes of website exploration than for performing purchase tasks. The most complex and time-consuming task for shoppers is the assessment of purchase options. The actual purchase and post-purchase tasks require less time and the inspection of fewer areas of interest. Personal involvement also plays a role in determining these patterns by increasing attention to the product area.
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    PublicationOpen Access
    Evaluation of accurate eye corner detection methods for gaze estimation
    (Bern Open Publishing, 2014) Bengoechea Irañeta, José Javier; Cerrolaza Martínez, Juan José; Villanueva Larre, Arantxa; Cabeza Laguna, Rafael; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    Accurate detection of iris center and eye corners appears to be a promising approach for low cost gaze estimation. In this paper we propose novel eye inner corner detection methods. Appearance and feature based segmentation approaches are suggested. All these methods are exhaustively tested on a realistic dataset containing images of subjects gazing at different points on a screen. We have demonstrated that a method based on a neural network presents the best performance even in light changing scenarios. In addition to this method, algorithms based on AAM and Harris corner detector present better accuracies than recent high performance face points tracking methods such as Intraface.
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    PublicationOpen Access
    Gaze tracking system model based on physical parameters
    (World Scientific Publishing, 2007) Villanueva Larre, Arantxa; Cabeza Laguna, Rafael; Porta Cuéllar, Sonia; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    In the past years, research in eye tracking development and applications has attracted much attention and the possibility of interacting with a computer employing just gaze information is becoming more and more feasible. Efforts in eye tracking cover a broad spectrum of fields, system mathematical modeling being an important aspect in this research. Expressions relating to several elements and variables of the gaze tracker would lead to establish geometric relations and to find out symmetrical behaviors of the human eye when looking at a screen. To this end a deep knowledge of projective geometry as well as eye physiology and kinematics are basic. This paper presents a model for a bright-pupil technique tracker fully based on realistic parameters describing the system elements. The system so modeled is superior to that obtained with generic expressions based on linear or quadratic expressions. Moreover, model symmetry knowledge leads to more effective and simpler calibration strategies, resulting in just two calibration points needed to fit the optical axis and only three points to adjust the visual axis. Reducing considerably the time spent by other systems employing more calibration points renders a more attractive model.