References of "Van Droogenbroeck, Marc"
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See detailAn evaluation of pixel-based methods for the detection of floating objects on the sea surface
Borghgraef, Alexander; Barnich, Olivier ULg; Lapierre, Fabian et al

in EURASIP Journal on Advances in Signal Processing (2010), 2010

Ship-based automatic detection of small floating objects on an agitated sea surface remains a hard problem. Our main concern is the detection of floating mines, which proved a real threat to shipping in ... [more ▼]

Ship-based automatic detection of small floating objects on an agitated sea surface remains a hard problem. Our main concern is the detection of floating mines, which proved a real threat to shipping in confined waterways during the first Gulf War, but applications include salvaging, search-and-rescue operation, perimeter, or harbour defense. Detection in infrared (IR) is challenging because a rough sea is seen as a dynamic background of moving objects with size order, shape, and temperature similar to those of the floating mine. In this paper we have applied a selection of background subtraction algorithms to the problem, and we show that the recent algorithms such as ViBe and behaviour subtraction, which take into account spatial and temporal correlations within the dynamic scene, significantly outperformthe more conventional parametric techniques, with only little prior assumptions about the physical properties of the scene. [less ▲]

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See detailReal-time processing of depth and color video streams to improve the reliability of depth maps
Pierard, Sébastien ULg; Leens, Jérôme ULg; Van Droogenbroeck, Marc ULg

Poster (2009, November)

Depth is a useful information in vision to understand the geometrical properties of an environment. Depth is traditionally computed in terms of a disparity map acquired by a stereoscopic system but, over ... [more ▼]

Depth is a useful information in vision to understand the geometrical properties of an environment. Depth is traditionally computed in terms of a disparity map acquired by a stereoscopic system but, over the last few years, several manufacturers have released single-lens cameras that directly capture depth information (also called range). This is an important technological breakthrough although range signals remain difficult to handle in practice, due to many reasons (low resolution, noise, low framerate, . . . ). Practitioners still struggle to use range data in their applications. The purpose of this paper is to give a brief introduction to range data (captured with a camera), discuss common limitations, and propose techniques to cope with difficulties typically encountered with range cameras. These techniques are based on a simultaneous view of the scene by a color and a depth camera that are combined to improve their interpretation in real time. [less ▲]

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See detailA simple and low cost angle measurement system for mobile robot positioning
Pierlot, Vincent ULg; Van Droogenbroeck, Marc ULg

in Workshop on Circuits, Systems and Signal Processing (ProRISC) (2009, November)

Positioning is a fundamental issue in mobile robot applications that can be achieved in multiple ways. Among these methods, triangulation with active beacons is widely used, robust, accurate, and flexible ... [more ▼]

Positioning is a fundamental issue in mobile robot applications that can be achieved in multiple ways. Among these methods, triangulation with active beacons is widely used, robust, accurate, and flexible. Our paper presents a new active beacon-based angle measurement system for indoor navigation using infrared signals. We propose a complete system for global positioning on a 2D plane based on the following parts: (1) a mirror, a lens, and a light guide, (2) a mini stepper motor and its controller, (3) an infrared receiver (TSOP7000), (4) a PIC microcontroller, and (5) three infrared beacons. The acquisition rate is 10 [Hz] and the accuracy is about 0.1 [degree]. The entire sensor is contained in a (8 X 8 X 8) [cm3] volume. The key innovation is the use of a cheap and simple infrared receiver as the main sensor for the angle measurement principle. The beacons too are simple cheap infrared LEDs. Furthermore, the system requires only one infrared communication channel, and no synchronization between the beacons and the robot is required. [less ▲]

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See detailA technique for building databases of annotated and realistic human silhouettes based on an avatar
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

in Annual Workshop on Circuits, Systems and Signal Processing (ProRISC) (2009, November)

The real-time interpretation of video scenes and human motion is a research field with a lot of applications. Awidely used pre-processing step is the background subtraction, which highlights silhouettes ... [more ▼]

The real-time interpretation of video scenes and human motion is a research field with a lot of applications. Awidely used pre-processing step is the background subtraction, which highlights silhouettes. In addition, example-based and learning-based approaches are attractive for the interpretation of complex scenes. But to be effective, such techniques need to be trained on samples of realistic human silhouettes. This paper presents a method to automatically build databases of artificial, realistic, and annotated human silhouettes. Our method, based on a 3D human avatar, allows to save additional data with the silhouettes, and to highlight the different body parts. These supplementary data may be application-driven. To help in evaluating the relevance of automatically generated databases, we suggest some practical solutions based on a visual signature of the databases. [less ▲]

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See detailTechniques to improve the foreground segmentation with a 3D camera and a color camera
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

(2009, November)

Nowadays, techniques for real-time interpretation of video scenes are widespread. Amongst these techniques, the foreground segmentation is one of the favorite. It can be applied to color images as well as ... [more ▼]

Nowadays, techniques for real-time interpretation of video scenes are widespread. Amongst these techniques, the foreground segmentation is one of the favorite. It can be applied to color images as well as depth maps. The point of using depth maps is straightforward as a single color camera is not able to provide depth information. Technologies capable to acquire 3D informations are thus adequate to complement color cameras in consumer products. Practice has shown that 3D or RGB signals, taken alone, are unreliable to extract the foreground under arbitrary conditions. Therefore we combine both modalities to counter the intrinsic limitations of both modalities, which is only possible if the problems specific to a technology are handled appropriately. This paper presents a new global approach for enhanced foreground segmentation that handles limitations to 3D and RGB in a combined way. [less ▲]

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See detailCombining Color, Depth, and Motion for Video Segmentation
Leens, Jérôme ULg; Pierard, Sébastien ULg; Barnich, Olivier et al

in Computer Vision Systems (2009)

This paper presents an innovative method to interpret the content of a video scene using a depth camera. Cameras that provide distance instead of color information are part of a promising young technology ... [more ▼]

This paper presents an innovative method to interpret the content of a video scene using a depth camera. Cameras that provide distance instead of color information are part of a promising young technology but they come with many diff culties: noisy signals, small resolution, and ambiguities, to cite a few. By taking advantage of the robustness to noise of a recent background subtraction algorithm, our method is able to extract useful information from the depth signals. We further enhance the robustness of the algorithm by combining this information with that of an RGB camera. In our experiments, we demonstrate this increased robustness and conclude by showing a practical example of an immersive application taking advantage of our algorithm. [less ▲]

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See detailClassification of scenarios for persons crossing a door frame based on the joint measurements of two radial distance sensors
Barnich, Olivier; Van Droogenbroeck, Marc ULg

Report (2009)

This report is the final report concerning the research project that involved the TELIM group from the University of Liège and BEA, a Belgian company active, among others, in the design and manufacturing ... [more ▼]

This report is the final report concerning the research project that involved the TELIM group from the University of Liège and BEA, a Belgian company active, among others, in the design and manufacturing of devices for people and vehicle detection. [less ▲]

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See detailAnchors of morphological operators and algebraic openings
Van Droogenbroeck, Marc ULg

in Hawkes, Peter (Ed.) Advances in Imaging and Electron Physics (2009)

Opening and closing operators play an important role in the field of mathematical morphology, mainly because of their useful property of idempotence, which is similar to the notion of ideal filter in ... [more ▼]

Opening and closing operators play an important role in the field of mathematical morphology, mainly because of their useful property of idempotence, which is similar to the notion of ideal filter in linear filtering. From a theoretical point of view, the study of openings has focused on the algebraic characterization of the operators themselves. Morphological filters have been studied for more than 30 years; the effects of the first filters (erosions, openings, and so on) are known in depth. In discussing the effects of a filter, it is not only the operator that is studied but also its relationship with the processed function or image and, in the particular case of mathematical morphology, the structuring element. In addition, there are several approaches to this analysis. For example, the analysis can consider the whole function or some subparts of the function, as in Van Droogenbroeck and Buckley (2005), who introduced the notion of morphological anchors. Anchors were defined in the context of morphological openings, as defined by the cascade of an erosion followed by a dilation. The extension to other kinds of openings is not straightforward. Despite the fact that all morphological openings induce the appearance of anchors, some opening operators (like the quantization opening defined in this chapter) might have no anchors. This chapter presents the theory of anchors related to morphological erosions and openings, and establishes some properties for the extended scope of algebraic openings. It is shown under which circumstances anchors exist for algebraic openings and how to locate some anchors; for example, it suffices for an opening to be spatial or shift-invariant to guarantee the existence of anchors. As for morphological openings, the existence of anchors may help clarify some algorithms or lead to new algorithms to compute algebraic openings. [less ▲]

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See detailViBe: a powerful random technique to estimate the background in video sequences
Barnich, Olivier ULg; Van Droogenbroeck, Marc ULg

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2009) (2009, April)

Background subtraction is a crucial step in many automatic video content analysis applications. While numerous acceptable techniques have been proposed so far for background extraction, there is still a ... [more ▼]

Background subtraction is a crucial step in many automatic video content analysis applications. While numerous acceptable techniques have been proposed so far for background extraction, there is still a need to produce more efficient algorithms in terms of adaptability to multiple environments, noise resilience, and computation efficiency. In this paper, we present a powerful method for background extraction that improves in accuracy and reduces the computational load. The main innovation concerns the use of a random policy to select values to build a samples-based estimation of the background. To our knowledge, it is the first time that a random aggregation is used in the field of background extraction. In addition, we propose a novel policy that propagates information between neighboring pixels of an image. Experiment detailed in this paper show how our method improves on other widely used techniques, and how it outperforms these techniques for noisy images. [less ▲]

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See detailDesign of a morphological moving object signature and application to human identification
Barnich, Olivier ULg; Van Droogenbroeck, Marc ULg

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2009) (2009, April)

Many computer vision systems try to infer semantic information about a video scene content by looking at the time series of the silhouettes of the moving objects. This paper proposes a new inter-frame ... [more ▼]

Many computer vision systems try to infer semantic information about a video scene content by looking at the time series of the silhouettes of the moving objects. This paper proposes a new inter-frame feature set (signature) based on piecewise surfacic descriptions of binary silhouettes. It captures the dynamics of moving objects and compacts it into a robust set of features suitable for classification. To assess its ability to represent motion information, we use it to build a complete gait recognition algorithm that we test on a database of 21 different subjects. To highlight the efficiency of our signature, we use frontal views instead of side views of persons, which is less discussed in literature and is considered to be harder as the movement of legs is not visible. In that context, the high recognition rates obtained (over 95% of correct identifications) proves that our signature is appropriate to describe moving objects. [less ▲]

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See detailVisual Backgound Extractor
Van Droogenbroeck, Marc ULg; Barnich, Olivier ULg

Patent (2009)

ViBe is a powerful pixel-based technique that detects the background in video sequences. Many experiments have shown that it performs better than the state-of-the-art techniques known in the scientific ... [more ▼]

ViBe is a powerful pixel-based technique that detects the background in video sequences. Many experiments have shown that it performs better than the state-of-the-art techniques known in the scientific literature. In addition the computational load is lower than simple background techniques implemented in commercial products. ViBe is the perfect solution for both softwares and hardware implementations. [less ▲]

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See detailFrontal-view gait recognition by intra- and inter-frame rectangle size distribution
Barnich, Olivier ULg; Van Droogenbroeck, Marc ULg

in Pattern Recognition Letters (2009), 30

Current trends seem to accredit gait as a sensible biometric feature for human identification, at least in a multimodal system. In addition to being a robust feature, gait is hard to fake and requires no ... [more ▼]

Current trends seem to accredit gait as a sensible biometric feature for human identification, at least in a multimodal system. In addition to being a robust feature, gait is hard to fake and requires no cooperation from the user. As in many video systems, the recognition confidence relies on the angle of view of the camera and on the illumination conditions, inducing a sensitivity to operational conditions that one may wish to lower. In this paper we present an efficient approach capable of recognizing people in frontal-view video sequences. The approach uses an intra-frame description of silhouettes which consists of a set of rectangles that will fit into any closed silhouette. A dynamic, inter-frame, dimension is then added by aggregating the size distributions of these rectangles over multiple successive frames. For each new frame, the inter-frame gait signature is updated and used to estimate the identity of the person detected in the scene. Finally, in order to smooth the decision on the identity, a majority vote is applied to previous results. In the final part of this article, we provide experimental results and discuss the accuracy of the classification for our own database of 21 known persons, and for a public database of 25 persons. [less ▲]

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See detailAnalyse et conception des systèmes de télécommunications
Van Droogenbroeck, Marc ULg

Learning material (2008)

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See detailPrincipes des télécommunications analogiques et numériques
Van Droogenbroeck, Marc ULg

Learning material (2008)

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See detailPrincipes des télécommunications analogiques et numériques
Van Droogenbroeck, Marc ULg

Learning material (2008)

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See detailTraitement numérique des images
Van Droogenbroeck, Marc ULg

Learning material (2007)

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See detailTraitement numérique des images (transparents)
Van Droogenbroeck, Marc ULg

Learning material (2007)

Detailed reference viewed: 867 (178 ULg)