883 research outputs found
"A Novel Feature-Based Approach for Indoor Monocular SLAM"
Camera tracking and the construction of a robust and accurate map in unknown environments are still challenging tasks in computer vision and robotic applications. Visual Simultaneous Localization and Mapping (SLAM) along with Augmented Reality (AR) are two important applications, and their performance is entirely dependent on the accuracy of the camera tracking routine. This paper presents a novel feature-based approach for the monocular SLAM problem using a hand-held camera in room-sized workspaces with a maximum scene depth of 4–5 m. In the core of the proposed method, there is a Particle Filter (PF) responsible for the estimation of extrinsic parameters of the camera. In addition, contrary to key-frame based methods, the proposed system tracks the camera frame by frame and constructs a robust and accurate map incrementally. Moreover, the proposed algorithm initially constructs a metric sparse map. To this end, a chessboard pattern with a known cell size has been placed in front of the camera for a few frames. This enables the algorithm to accurately compute the pose of the camera and therefore, the depth of the primary detected natural feature points are easily calculated. Afterwards, camera pose estimation for each new incoming frame is carried out in a framework that is merely working with a set of visible natural landmarks. Moreover, to recover the depth of the newly detected landmarks, a delayed approach based on linear triangulation is used. The proposed method is applied to a realworld VGA quality video (640 × 480 pixels) where the translation error of the camera pose is less than 2 cm on average and the orientation error is less than 3 degrees, which indicates the effectiveness and accuracy of the developed algorithm
Musical Approaches for Working with Time-Delayed Feedback Networks
(Abstract to follow
Models and estimators for markerless human motion tracking
In this work, we analyze the diferent components of a model-based motion tracking system.
The system consists in: a human body model, an estimator, and a likelihood or cost
function
Lidar-based scene understanding for autonomous driving using deep learning
With over 1.35 million fatalities related to traffic accidents worldwide, autonomous driving was foreseen at the beginning of this century as a feasible solution to improve security in our roads. Nevertheless, it is meant to disrupt our transportation paradigm, allowing to reduce congestion, pollution, and costs, while increasing the accessibility, efficiency, and reliability of the transportation for both people and goods. Although some advances have gradually been transferred into commercial vehicles in the way of Advanced Driving Assistance Systems (ADAS) such as adaptive cruise control, blind spot detection or automatic parking, however, the technology is far from mature. A full understanding of the scene is actually needed so that allowing the vehicles to be aware of the surroundings, knowing the existing elements of the scene, as well as their motion, intentions and interactions.
In this PhD dissertation, we explore new approaches for understanding driving scenes from 3D LiDAR point clouds by using Deep Learning methods. To this end, in Part I we analyze the scene from a static perspective using independent frames to detect the neighboring vehicles. Next, in Part II we develop new ways for understanding the dynamics of the scene. Finally, in Part III we apply all the developed methods to accomplish higher level challenges such as segmenting moving obstacles while obtaining their rigid motion vector over the ground.
More specifically, in Chapter 2 we develop a 3D vehicle detection pipeline based on a multi-branch deep-learning architecture and propose a Front (FR-V) and a Bird’s Eye view (BE-V) as 2D representations of the 3D point cloud to serve as input for training our models. Later on, in Chapter 3 we apply and further test this method on two real uses-cases, for pre-filtering moving
obstacles while creating maps to better localize ourselves on subsequent days, as well as for vehicle tracking. From the dynamic perspective, in Chapter 4 we learn from the 3D point cloud a novel dynamic feature that resembles optical flow from RGB images. For that, we develop a new approach to leverage RGB optical flow as pseudo ground truth for training purposes but allowing the use of only 3D LiDAR data at inference time. Additionally, in Chapter 5 we explore the benefits of combining classification and regression learning problems to face the optical flow estimation task in a joint coarse-and-fine manner. Lastly, in Chapter 6 we gather the previous methods and demonstrate that with these independent tasks we can guide the learning of higher challenging problems such as segmentation and motion estimation of moving vehicles from our own moving perspective.Con más de 1,35 millones de muertes por accidentes de tráfico en el mundo, a principios de siglo se predijo que la conducción autónoma serÃa una solución viable para mejorar la seguridad en nuestras carreteras. Además la conducción autónoma está destinada a cambiar nuestros paradigmas de transporte, permitiendo reducir la congestión del tráfico, la contaminación y el coste, a la vez que aumentando la accesibilidad, la eficiencia y confiabilidad del transporte tanto de personas como de mercancÃas. Aunque algunos avances, como el control de crucero adaptativo, la detección de puntos ciegos o el estacionamiento automático, se han transferido gradualmente a vehÃculos comerciales en la forma de los Sistemas Avanzados de Asistencia a la Conducción (ADAS), la tecnologÃa aún no ha alcanzado el suficiente grado de madurez. Se necesita una comprensión completa de la escena para que los vehÃculos puedan entender el entorno, detectando los elementos presentes, asà como su movimiento, intenciones e interacciones. En la presente tesis doctoral, exploramos nuevos enfoques para comprender escenarios de conducción utilizando nubes de puntos en 3D capturadas con sensores LiDAR, para lo cual empleamos métodos de aprendizaje profundo. Con este fin, en la Parte I analizamos la escena desde una perspectiva estática para detectar vehÃculos. A continuación, en la Parte II, desarrollamos nuevas formas de entender las dinámicas del entorno. Finalmente, en la Parte III aplicamos los métodos previamente desarrollados para lograr desafÃos de nivel superior, como segmentar obstáculos dinámicos a la vez que estimamos su vector de movimiento sobre el suelo. EspecÃficamente, en el CapÃtulo 2 detectamos vehÃculos en 3D creando una arquitectura de aprendizaje profundo de dos ramas y proponemos una vista frontal (FR-V) y una vista de pájaro (BE-V) como representaciones 2D de la nube de puntos 3D que sirven como entrada para entrenar nuestros modelos. Más adelante, en el CapÃtulo 3 aplicamos y probamos aún más este método en dos casos de uso reales, tanto para filtrar obstáculos en movimiento previamente a la creación de mapas sobre los que poder localizarnos mejor en los dÃas posteriores, como para el seguimiento de vehÃculos. Desde la perspectiva dinámica, en el CapÃtulo 4 aprendemos de la nube de puntos en 3D una caracterÃstica dinámica novedosa que se asemeja al flujo óptico sobre imágenes RGB. Para ello, desarrollamos un nuevo enfoque que aprovecha el flujo óptico RGB como pseudo muestras reales para entrenamiento, usando solo information 3D durante la inferencia. Además, en el CapÃtulo 5 exploramos los beneficios de combinar los aprendizajes de problemas de clasificación y regresión para la tarea de estimación de flujo óptico de manera conjunta. Por último, en el CapÃtulo 6 reunimos los métodos anteriores y demostramos que con estas tareas independientes podemos guiar el aprendizaje de problemas de más alto nivel, como la segmentación y estimación del movimiento de vehÃculos desde nuestra propia perspectivaAmb més d’1,35 milions de morts per accidents de trà nsit al món, a principis de segle es va
predir que la conducció autònoma es convertiria en una solució viable per millorar la seguretat
a les nostres carreteres. D’altra banda, la conducció autònoma està destinada a canviar els
paradigmes del transport, fent possible aixà reduir la densitat del trà nsit, la contaminació i
el cost, alhora que augmentant l’accessibilitat, l’eficiència i la confiança del transport tant de
persones com de mercaderies. Encara que alguns avenços, com el control de creuer adaptatiu,
la detecció de punts cecs o l’estacionament automà tic, s’han transferit gradualment a vehicles
comercials en forma de Sistemes Avançats d’Assistència a la Conducció (ADAS), la tecnologia
encara no ha arribat a aconseguir el grau suficient de maduresa. És necessà ria, doncs, una
total comprensió de l’escena de manera que els vehicles puguin entendre l’entorn, detectant els
elements presents, aixà com el seu moviment, intencions i interaccions.
A la present tesi doctoral, explorem nous enfocaments per tal de comprendre les diferents
escenes de conducció utilitzant núvols de punts en 3D capturats amb sensors LiDAR, mitjançant
l’ús de mètodes d’aprenentatge profund. Amb aquest objectiu, a la Part I analitzem l’escena des
d’una perspectiva està tica per a detectar vehicles. A continuació, a la Part II, desenvolupem
noves formes d’entendre les dinà miques de l’entorn. Finalment, a la Part III apliquem els
mètodes prèviament desenvolupats per a aconseguir desafiaments d’un nivell superior, com, per
exemple, segmentar obstacles dinà mics al mateix temps que estimem el seu vector de moviment
respecte al terra.
Concretament, al CapÃtol 2 detectem vehicles en 3D creant una arquitectura d’aprenentatge
profund amb dues branques, i proposem una vista frontal (FR-V) i una vista d’ocell (BE-V)
com a representacions 2D del núvol de punts 3D que serveixen com a punt de partida per
entrenar els nostres models. Més endavant, al CapÃtol 3 apliquem i provem de nou aquest
mètode en dos casos d’ús reals, tant per filtrar obstacles en moviment prèviament a la creació
de mapes en els quals poder localitzar-nos millor en dies posteriors, com per dur a terme
el seguiment de vehicles. Des de la perspectiva dinà mica, al CapÃtol 4 aprenem una nova
caracterÃstica dinà mica del núvol de punts en 3D que s’assembla al flux òptic sobre imatges
RGB. Per a fer-ho, desenvolupem un nou enfocament que aprofita el flux òptic RGB com pseudo
mostres reals per a entrenament, utilitzant només informació 3D durant la inferència. Després,
al CapÃtol 5 explorem els beneficis que s’obtenen de combinar els aprenentatges de problemes
de classificació i regressió per la tasca d’estimació de flux òptic de manera conjunta. Finalment,
al CapÃtol 6 posem en comú els mètodes anteriors i demostrem que mitjançant aquests processos
independents podem abordar l’aprenentatge de problemes més complexos, com la segmentació
i estimació del moviment de vehicles des de la nostra pròpia perspectiva
Event-based Vision: A Survey
Event cameras are bio-inspired sensors that differ from conventional frame
cameras: Instead of capturing images at a fixed rate, they asynchronously
measure per-pixel brightness changes, and output a stream of events that encode
the time, location and sign of the brightness changes. Event cameras offer
attractive properties compared to traditional cameras: high temporal resolution
(in the order of microseconds), very high dynamic range (140 dB vs. 60 dB), low
power consumption, and high pixel bandwidth (on the order of kHz) resulting in
reduced motion blur. Hence, event cameras have a large potential for robotics
and computer vision in challenging scenarios for traditional cameras, such as
low-latency, high speed, and high dynamic range. However, novel methods are
required to process the unconventional output of these sensors in order to
unlock their potential. This paper provides a comprehensive overview of the
emerging field of event-based vision, with a focus on the applications and the
algorithms developed to unlock the outstanding properties of event cameras. We
present event cameras from their working principle, the actual sensors that are
available and the tasks that they have been used for, from low-level vision
(feature detection and tracking, optic flow, etc.) to high-level vision
(reconstruction, segmentation, recognition). We also discuss the techniques
developed to process events, including learning-based techniques, as well as
specialized processors for these novel sensors, such as spiking neural
networks. Additionally, we highlight the challenges that remain to be tackled
and the opportunities that lie ahead in the search for a more efficient,
bio-inspired way for machines to perceive and interact with the world
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