1,317 research outputs found
A system for learning statistical motion patterns
Analysis of motion patterns is an effective approach for anomaly detection and behavior prediction. Current approaches for the analysis of motion patterns depend on known scenes, where objects move in predefined ways. It is highly desirable to automatically construct object motion patterns which reflect the knowledge of the scene. In this paper, we present a system for automatically learning motion patterns for anomaly detection and behavior prediction based on a proposed algorithm for robustly tracking multiple objects. In the tracking algorithm, foreground pixels are clustered using a fast accurate fuzzy k-means algorithm. Growing and prediction of the cluster centroids of foreground pixels ensure that each cluster centroid is associated with a moving object in the scene. In the algorithm for learning motion patterns, trajectories are clustered hierarchically using spatial and temporal information and then each motion pattern is represented with a chain of Gaussian distributions. Based on the learned statistical motion patterns, statistical methods are used to detect anomalies and predict behaviors. Our system is tested using image sequences acquired, respectively, from a crowded real traffic scene and a model traffic scene. Experimental results show the robustness of the tracking algorithm, the efficiency of the algorithm for learning motion patterns, and the encouraging performance of algorithms for anomaly detection and behavior prediction
A system for learning statistical motion patterns
Analysis of motion patterns is an effective approach for anomaly detection and behavior prediction. Current approaches for the analysis of motion patterns depend on known scenes, where objects move in predefined ways. It is highly desirable to automatically construct object motion patterns which reflect the knowledge of the scene. In this paper, we present a system for automatically learning motion patterns for anomaly detection and behavior prediction based on a proposed algorithm for robustly tracking multiple objects. In the tracking algorithm, foreground pixels are clustered using a fast accurate fuzzy k-means algorithm. Growing and prediction of the cluster centroids of foreground pixels ensure that each cluster centroid is associated with a moving object in the scene. In the algorithm for learning motion patterns, trajectories are clustered hierarchically using spatial and temporal information and then each motion pattern is represented with a chain of Gaussian distributions. Based on the learned statistical motion patterns, statistical methods are used to detect anomalies and predict behaviors. Our system is tested using image sequences acquired, respectively, from a crowded real traffic scene and a model traffic scene. Experimental results show the robustness of the tracking algorithm, the efficiency of the algorithm for learning motion patterns, and the encouraging performance of algorithms for anomaly detection and behavior prediction
Learning from human-robot interaction
En los últimos años cada vez es más frecuente ver robots en los hogares. La robótica está cada vez más presente en muchos aspectos de nuestras vidas diarias, en aparatos de asistencia doméstica, coches autónomos o asistentes personales. La interacción entre estos robots asistentes y los usuarios es uno de los aspectos clave en la robótica de servicio. Esta interacción necesita ser cómoda e intuitiva para que sea efectiva su utilización. Estas interacciones con los usuarios son necesarias para que el robot aprenda y actualice de manera natural tanto su modelo del mundo como sus capacidades. Dentro de los sistemas roboticos de servicio, hay muchos componentes que son necesarios para su buen funcionamiento. Esta tesis esta centrada en el sistema de percepción visual de dichos sistemas.Para los humanos la percepción visual es uno de los componentes más esenciales, permitiendo tareas como reconocimiento de objetos u otras personas, o estimación de información 3D. Los grandes logros obtenidos en los últimos años en tareas de reconocimiento automático utilizan los enfoques basados en aprendizaje automático, en particular técnicas de deep learning. La mayoría de estos trabajos actuales se centran en modelos entrenados 'a priori' en un conjunto de datos muy grandes. Sin embargo, estos modelos, aunque entrenados en una gran cantidad de datos, no pueden, en general, hacer frente a los retos que aparecen al tratar con datos reales en entornos domésticos. Por ejemplo, es frecuente que se de el caso de tener nuevos objetos que no existían durante el entrenamiento de los modelos. Otro reto viene de la dispersión de los objetos, teniendo objetos que aparecen muy raramente y por lo tanto habia muy pocos, o ningún, ejemplos en los datos de entenamiento disponibles al crear el modelo.Esta tesis se ha desarrollado dentro del contexto del proyecto IGLU (Interactive Grounded Language Understanding). Dentro del proyecto y sus objetivos, el objetivo principal de esta Tesis doctoral es investigar métodos novedosos para que un robot aprenda de manera incremental mediante la interacción multimodal con el usuario.Desarrollando dicho objetivo principal, los principales trabajos desarrollados durante esta tesis han sido:-Crear un benchmark más adecuado para las tareas de aprendizaje mediante la interacción natural de usuario y robot. Por ejemplo, la mayoría de los datasets para la tarea de reconocimiento de objetos se centra en fotos de diferentes escenarios con múltiples clases por foto. Es necesario un dataset que combine interacción usuario robot con aprendizaje de objetos.-Mejorar sistemas existentes de aprendizaje de objetos y adecuarlos para aprendizaje desde la interacción multimodal humana. Los trabajos de detección de objetos se focalizan en detectar todos los objetos aprendidos en una imagen. Nuestro objetivo es usar la interacción para encontrar el objeto de referencia y aprenderlo incrementalmente.-Desarrollar métodos de aprendizaje incremental que se puedan utilizar en escenarios incrementales, p.e., la aparición de una nueva clase de objeto o cambios a lo largo del tiempo dentro de una clase objetos. Nuestro objetivo es diseñar un sistema que pueda aprender clases desde cero y que pueda actualizar los datos cuando estos aparecen.-Crear un completo prototipo para el aprendizaje incremental y multimodal usando la interacción humana-robot. Se necesita realizar la integración de los distintos métodos desarrollados como parte de los otros objetivos y evaluarlo.<br /
Modelling and tracking objects with a topology preserving self-organising neural network
Human gestures form an integral part in our everyday communication. We use
gestures not only to reinforce meaning, but also to describe the shape of objects,
to play games, and to communicate in noisy environments. Vision systems that
exploit gestures are often limited by inaccuracies inherent in handcrafted models.
These models are generated from a collection of training examples which requires
segmentation and alignment. Segmentation in gesture recognition typically involves manual intervention, a time consuming process that is feasible only for a
limited set of gestures. Ideally gesture models should be automatically acquired
via a learning scheme that enables the acquisition of detailed behavioural knowledge only from topological and temporal observation.
The research described in this thesis is motivated by a desire to provide a framework for the unsupervised acquisition and tracking of gesture models. In any
learning framework, the initialisation of the shapes is very crucial. Hence, it would
be beneficial to have a robust model not prone to noise that can automatically correspond the set of shapes. In the first part of this thesis, we develop a framework
for building statistical 2D shape models by extracting, labelling and corresponding
landmark points using only topological relations derived from competitive hebbian learning. The method is based on the assumption that correspondences can
be addressed as an unsupervised classification problem where landmark points
are the cluster centres (nodes) in a high-dimensional vector space. The approach
is novel in that the network can be used in cases where the topological structure of
the input pattern is not known a priori thus no topology of fixed dimensionality is imposed onto the network.
In the second part, we propose an approach to minimise the user intervention
in the adaptation process, which requires to specify a priori the number of nodes
needed to represent an object, by utilising an automatic criterion for maximum
node growth. Furthermore, this model is used to represent motion in image sequences by initialising a suitable segmentation that separates the object of interest
from the background. The segmentation system takes into consideration some illumination tolerance, images as inputs from ordinary cameras and webcams, some
low to medium cluttered background avoiding extremely cluttered backgrounds,
and that the objects are at close range from the camera.
In the final part, we extend the framework for the automatic modelling and
unsupervised tracking of 2D hand gestures in a sequence of k frames. The aim
is to use the tracked frames as training examples in order to build the model and
maintain correspondences. To do that we add an active step to the Growing Neural Gas (GNG) network, which we call Active Growing Neural Gas (A-GNG) that
takes into consideration not only the geometrical position of the nodes, but also the
underlined local feature structure of the image, and the distance vector between
successive images. The quality of our model is measured through the calculation
of the topographic product. The topographic product is our topology preserving
measure which quantifies the neighbourhood preservation.
In our system we have applied specific restrictions in the velocity and the appearance of the gestures to simplify the difficulty of the motion analysis in the gesture representation. The proposed framework has been validated on applications
related to sign language. The work has great potential in Virtual Reality (VR) applications where the learning and the representation of gestures becomes natural
without the need of expensive wear cable sensors
Fast Online Incremental Learning with Few Examples For Online Handwritten Character Recognition.
International audienceAn incremental learning strategy for handwritten character recognition is proposed in this paper. The strategy is online and fast, in the sense that any new character class can be instantly learned by the system. The proposed strategy aims at overcoming the problem of lack of training data when introducing a new character class. Synthetic handwritten characters generation is used for this purpose. Our approach uses a Fuzzy Inference System (FIS) as a classifier. Results have shown that a good recognition rate (about 90%) can be achieved using only 3 training examples. And such rate rapidly improves reaching 96% for 10 examples, and 97% for 30 ones
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