Recovering a deformable 3D surface from a single image is an ill-posed problem because of the depth ambiguities. The resolution to this ambiguity normally requires prior knowledge about the most probable deformations that the surface can support. Many methods that address this problem have been proposed in the literature. Some of them rely on physical properties, while others learn the principal deformations of the object or are based on a reference textured image. However, they present some limitations such as high computational cost or the lack of the possibility of recovering the 3D shape. As an alternative to existing solutions, this paper provides a novel approach that simultaneously recovers the non-rigid 3D shape and the camera pose in real time from a single image. This proposal relies on an efficient particle filter that performs an intelligent search of a database of deformations. We present an exhaustive Design of Experiments to obtain the optimal parametrization of the particle filter, as well as a set of results to demonstrate the visual quality and the performance of our approach. (C) 2014 Elsevier Inc. All rights reserved.

This article presents a comprehensive framework for the recognition of untextured 3D models in a single image. The method proposed here is capable of recovering a 3D pose in a few hundred of milliseconds, which is a difficult challenge using this type of model. This proposal deals with 3D models that lack texture, so geometry features of the model are used as a basis of the 3D pose retrieval. An automatic process extracts the junctions and contours of the model, replacing the user interaction. Junctions will provide us an efficient mechanism to generate candidate matches, while contours will select the correct match based on a robust shape similarity evaluation. Our method only requires the 3D triangle mesh of the model as input, since the rest of the process is done automatically. We demonstrate the behaviour of our approach against a variety of real scenes and models. Moreover, we explain how to face the first pose problem in a robust way using a history of votes. We also present a study of the method parameterisation, describing the influence of each parameter. (c) 2012 Elsevier Inc. All rights reserved.

Marker systems are a widely used optical tracking method that does not support occlusions. Thus, this paper proposes a new marker design to overcome the problem of marker occlusions. It is highly adaptable, because it can be used by any marker tracking system that uses its central area to codify the digital identification. Our proposal takes advantage of an untapped frame to place some textures that will be tracked during marker occlusion. In addition, these textures are customizable, which lets users make their own designs. Two tracking methods are combined to offer a robust tracking, updating the six degrees of freedom of the camera in real time. The first one is a fast technique based on temporal coherence, whereas the second one is a robust technique based on appearance, which is used as a recovery mode. Copyright (c) 2012 John Wiley & Sons, Ltd.

Marker systems are a widely used optical tracking method that does not support occlusions. Thus, this paper proposes a new marker design to overcome the problem of marker occlusions. It is highly adaptable, because it can be used by any marker tracking system that uses its central area to codify the digital identification. Our proposal takes advantage of an untapped frame to place some textures that will be tracked during marker occlusion. In addition, these textures are customizable, which lets users make their own designs. Two tracking methods are combined to offer a robust tracking, updating the six degrees of freedom of the camera in real time. The first one is a fast technique based on temporal coherence, whereas the second one is a robust technique based on appearance, which is used as a recovery mode. Copyright (c) 2012 John Wiley & Sons, Ltd.

This paper investigates the effect of user grasping position on the performance of haptic rendering. Two dynamic models, with seven and eleven parameters, respectively, have been used to characterize the PHANToM haptic interface and the user. The parameter variability analysis shows that user grasping position significantly affects system dynamics. This variation also influences the phase margin of the system, leading to different damping factors in response to contacts with rigid virtual objects. To compensate this effect, an adaptive haptic rendering has been developed and successfully implemented, imposing a similar damping factor in the transient responses for all grip positions.