Jose Manuel Alvarez, & Antonio Lopez. (2011). Road Detection Based on Illuminant Invariance. TITS - IEEE Transactions on Intelligent Transportation Systems, 12(1), 184–193.
Abstract: By using an onboard camera, it is possible to detect the free road surface ahead of the ego-vehicle. Road detection is of high relevance for autonomous driving, road departure warning, and supporting driver-assistance systems such as vehicle and pedestrian detection. The key for vision-based road detection is the ability to classify image pixels as belonging or not to the road surface. Identifying road pixels is a major challenge due to the intraclass variability caused by lighting conditions. A particularly difficult scenario appears when the road surface has both shadowed and nonshadowed areas. Accordingly, we propose a novel approach to vision-based road detection that is robust to shadows. The novelty of our approach relies on using a shadow-invariant feature space combined with a model-based classifier. The model is built online to improve the adaptability of the algorithm to the current lighting and the presence of other vehicles in the scene. The proposed algorithm works in still images and does not depend on either road shape or temporal restrictions. Quantitative and qualitative experiments on real-world road sequences with heavy traffic and shadows show that the method is robust to shadows and lighting variations. Moreover, the proposed method provides the highest performance when compared with hue-saturation-intensity (HSI)-based algorithms.
Keywords: road detection
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Enrique Cabello, Cristina Conde, Angel Serrano, Licesio Rodriguez, & David Vazquez. (2006). Empleo de sistemas biométricos para el reconocimiento de personas en aeropuertos.
Abstract: El presente proyecto se desarrolló a lo largo del año 2005, probando un prototipo de un sistema de verificación facial con imágenes extraídas de las cámaras de video vigilancia del aeropuerto de Barajas. Se diseñaron varios experimentos, agrupados en dos clases. En el primer tipo, el sistema es entrenado con imágenes obtenidas en condiciones de laboratorio y luego probado con imágenes extraídas de las cámaras de video vigilancia del aeropuerto de Barajas. En el segundo caso, tanto las imágenes de entrenamiento como las de prueba corresponden a imágenes extraídas de Barajas. Se ha desarrollado un sistema completo, que incluye adquisición y digitalización de las imágenes, localización y recorte de las caras en escena, verificación de sujetos y obtención de resultados. Los resultados muestran, que, en general, un sistema de verificación facial basado en imágenes puede ser una ayuda a un operario que deba estar vigilando amplias zonas.
Keywords: Surveillance; Face detection; Face recognition
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Bart M. Ter Haar Romeny, W. Niessen, J. Weickert, P. Van Roermund, W. Van Enk, Antonio Lopez, et al. (1996). Orientation detection of trabecular bone. In Biophysics and Molecular Biology, International Biophysics Congress. Volume 65, pgs. P–H5–43.
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Daniel Hernandez, Lukas Schneider, Antonio Espinosa, David Vazquez, Antonio Lopez, Uwe Franke, et al. (2017). Slanted Stixels: Representing San Francisco's Steepest Streets. In 28th British Machine Vision Conference.
Abstract: In this work we present a novel compact scene representation based on Stixels that infers geometric and semantic information. Our approach overcomes the previous rather restrictive geometric assumptions for Stixels by introducing a novel depth model to account for non-flat roads and slanted objects. Both semantic and depth cues are used jointly to infer the scene representation in a sound global energy minimization formulation. Furthermore, a novel approximation scheme is introduced that uses an extremely efficient over-segmentation. In doing so, the computational complexity of the Stixel inference algorithm is reduced significantly, achieving real-time computation capabilities with only a slight drop in accuracy. We evaluate the proposed approach in terms of semantic and geometric accuracy as well as run-time on four publicly available benchmark datasets. Our approach maintains accuracy on flat road scene datasets while improving substantially on a novel non-flat road dataset.
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Carme Julia, Angel Sappa, Felipe Lumbreras, Joan Serrat, & Antonio Lopez. (2008). Rank Estimation in 3D Multibody Motion Segmentation. Electronic Letters, 44(4), 279–280.
Abstract: A novel technique for rank estimation in 3D multibody motion segmentation is proposed. It is based on the study of the frequency spectra of moving rigid objects and does not use or assume a prior knowledge of the objects contained in the scene (i.e. number of objects and motion). The significance of rank estimation on multibody motion segmentation results is shown by using two motion segmentation algorithms over both synthetic and real data.
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David Lloret, Antonio Lopez, & Joan Serrat. (1997). Rigid Registration of CT and MR volumes based on Rothes creases. In (SNRFAI’97) 7th Spanish National Symposium on Pattern Recognition and Image Analysis (pp. 1–6).
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Antonio Lopez. (1997). Ridge/Valley-like structures: Creases, separatrices and drainage patterns.
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Antonio Lopez, & Joan Serrat. (1995). Image Analysis through Surface Geometric Descriptors. In VI National Simposium on Pattern Recognition and image Analysis..
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Antonio Lopez, & Joan Serrat. (1996). Tracing crease curves by solving a system of differential equations. In ECCV 1996 (Vol. 1064). LNCS.
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David Lloret, Joan Serrat, Antonio Lopez, & Juan J. Villanueva. (2003). Ultrasound to MR Volume Registration for Brain Sinking Measurement. In 1rst. Iberian Conference on Pattern Recognition and Image Analysis IbPRIA 2003 (Vol. 2652, pp. 420–427). LNCS.
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Felipe Lumbreras, & Joan Serrat. (1996). Wavelet filtering for the segmentation of marble images. Optical Engineering, 35(10).
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Felipe Lumbreras, & Joan Serrat. (1996). Segmentation of petrographical images of marbles. Computers and Geosciences, 22(5), 547–558.
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Antonio Lopez, Jiaolong Xu, Jose Luis Gomez, David Vazquez, & German Ros. (2017). From Virtual to Real World Visual Perception using Domain Adaptation -- The DPM as Example. In Gabriela Csurka (Ed.), Domain Adaptation in Computer Vision Applications (pp. 243–258). Springer.
Abstract: Supervised learning tends to produce more accurate classifiers than unsupervised learning in general. This implies that training data is preferred with annotations. When addressing visual perception challenges, such as localizing certain object classes within an image, the learning of the involved classifiers turns out to be a practical bottleneck. The reason is that, at least, we have to frame object examples with bounding boxes in thousands of images. A priori, the more complex the model is regarding its number of parameters, the more annotated examples are required. This annotation task is performed by human oracles, which ends up in inaccuracies and errors in the annotations (aka ground truth) since the task is inherently very cumbersome and sometimes ambiguous. As an alternative we have pioneered the use of virtual worlds for collecting such annotations automatically and with high precision. However, since the models learned with virtual data must operate in the real world, we still need to perform domain adaptation (DA). In this chapter we revisit the DA of a deformable part-based model (DPM) as an exemplifying case of virtual- to-real-world DA. As a use case, we address the challenge of vehicle detection for driver assistance, using different publicly available virtual-world data. While doing so, we investigate questions such as: how does the domain gap behave due to virtual-vs-real data with respect to dominant object appearance per domain, as well as the role of photo-realism in the virtual world.
Keywords: Domain Adaptation
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W. Niessen, Antonio Lopez, W. Van Enk, P. Van Roermund, Bart M. Ter Haar Romeny, & M. Viergever. (1997). Multiscale Trabecular Bone Orientation Analysis. In (SNRFAI’97) 7th Spanish National Symposium on Pattern Recognition and Image Analysis (pp. 19–24).
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W. Niessen, Antonio Lopez, W. Van Enk, P. Van Roermund, Bart M. Ter Haar Romeny, & M. Viergever. (1997). In Vivo Analysis of Trabecular Bone Architecture. In Information Processing in Medical Imaging. IMPI 1997 (Vol. 1230, pp. 435–440). LNCS.
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