patrick hebert - Academia.edu (original) (raw)

Papers by patrick hebert

M. Fischler et al., "Random Sample consensus: A paradigm for model fitting with applications to i... more M. Fischler et al., "Random Sample consensus: A paradigm for model fitting with applications to image analysis and automated cartogra phy'.

Ieee International Conference on Image Processing 2005, Oct 14, 2005

In image-based light field rendering, many efforts have been made to improve the efficiency of th... more In image-based light field rendering, many efforts have been made to improve the efficiency of the modeling. This efficiency pertains to the photorealism and compression of a given model. We propose a new way to improve these two aspects. We show that it is better to sample the plenoptic function on a surface that minimizes the frequency content of all its lumispheres. We also demonstrate an additional constraint based on the visual hull that further guides the sampling of the plenoptic function around an object. We propose a corresponding algorithm that relies on images alone and only suppose that the modeled object is opaque. This algorithm is then validated on both real and synthetic data sets.

18Th International Conference on Pattern Recognition, Aug 20, 2006

MONNET is a visual surveillance system for tracking pedestrians over extended premises. The MONNE... more MONNET is a visual surveillance system for tracking pedestrians over extended premises. The MONNET system is composed of intelligent nodes, which exchange information on the individually tracked pedestrians in an asynchronous manner. Each node in MONNET builds an appearance model for every observed pedestrian and compares it with models received from other nodes. The compact appearance models based on colour cues and face biometrics are stored locally on each node. The system is dynamically reconfigurable since its design allows for adding/removing nodes in a simple manner, comparable to the 'plug and play' technology. MONNET also contains an optional 'observer' node for interactive data visualization. This node displays a user interface which allows a human operator to observe and to interact in real-time with the distributed tracking process. MONNET was extensively tested with and without user input, and it is able to function correctly in both modes.

Abstract This paper presents an efficient procedure for calibrating a wide area system of synchro... more Abstract This paper presents an efficient procedure for calibrating a wide area system of synchronized cameras with respect to a global coordinate system. The flexibility of this procedure lies in its use of a hand-held calibration target that is automatically detected in ...

... Patrick Hébert, Denis Laurendeau and Denis Poussart. Bibtex: @inproceedings{Hébert249, author... more ... Patrick Hébert, Denis Laurendeau and Denis Poussart. Bibtex: @inproceedings{Hébert249, author = {Patrick Hébert and Denis Laurendeau and Denis Poussart }, title = { Surface profile description: Invariant stable extraction of straight line segments }, booktitle = { Proc. ...

Sixth International Conference on 3-D Digital Imaging and Modeling (3DIM 2007), 2007

This paper adopts a sampling perspective to surface light field modeling. This perspective elimin... more This paper adopts a sampling perspective to surface light field modeling. This perspective eliminates the need of using the actual object surface in the surface light field definition. Instead, the surface ought to provide only a parameterization of the surface light field function that specifically reduces aliasing artifacts visible at rendering. To find that surface, we propose a new criterion that aims at optimizing the smoothness of the angular distribution of the light rays emanating from each point on the surface. The main advantage of this approach is to be independent of any specific reflectance model. The proposed criterion is compared to widely used criteria found in multi-view stereo and its effectiveness is validated for modeling the appearance of objects having various unknown reflectance properties using calibrated images alone.

Proceedings of IEEE International Conference on Robotics and Automation, 1996

A mobile robot navigates in an environment and incrementally builds a map while locating itself. ... more A mobile robot navigates in an environment and incrementally builds a map while locating itself. The quality of the map depends on the sensor models. Due to the difficulty of defining a stochastic odometric model, the classical approach based on Kalman filtering is revisited in order to decouple the information provided by the odometric sensor and exteroceptive sensors. The proposed

Proceedings of IEEE Conference on Computer Vision and Pattern Recognition, 1993

... Poussart Computer Vision and Digital Systems Laboratory Department of Electrical Engineering ... more ... Poussart Computer Vision and Digital Systems Laboratory Department of Electrical Engineering Laval University, Qu6bec, Canada e-mail: [hebert, laurend, poussart ... For this purpose, a spring-rod physical model is defined as illustrated in figure 7. Springs are anchored to data ...

Proceedings of 12th International Conference on Pattern Recognition, 1994

This paper is concerned with the reliability of a shape description recovered from a set of scatt... more This paper is concerned with the reliability of a shape description recovered from a set of scattered measurements. The recovering process of the description should not introduce a bias that is caused by specific acquisition conditions such as the presence of spurious measurements and the relative position of the sensor with respect to the object. Moreover, the recovered description should be stable for a sampling variation. While the fitting stage is based on a measurement error model which takes into account the sensor's viewpoint, the stability with sampling is tested by perturbing an hypothesized section. The validity of the approach is demonstrated by extracting reliable estimates of polynomial sections (lines, conics) from surface profile range data obtained from one or several viewpoints

Intelligent Robots and Computer Vision XIII: 3D Vision, Product Inspection, and Active Vision, 1994

Lecture Notes in Computer Science, 2008

We describe an accurate keypoint detector that is stable under viewpoint change. In this paper, k... more We describe an accurate keypoint detector that is stable under viewpoint change. In this paper, keypoints correspond to actual junctions in the image. The principle of ASN differs fundamentally from other keypoint detectors. At each position in the image and before any detection, it systematically estimates the position of a potential junction from the local gradient field. Keypoints then appear where multiple position estimates are attracted. This approach allows the detector to adapt in shape and size to the image content. One further obtains the area where the keypoint has attracted solutions. Comparative results with other detectors show the improved accuracy and stability with viewpoint change.