Publications

Journal papers

Damien Douxchamps, Kunihiro Chihara, High-accuracy and robust localization of large control markers for geometric camera calibration, IEEE Trans. on Pattern Analysis and Machine Intelligence, Vol. 31, No. 2, Feb. 2009, pp.376-383. BibTeX, PDF
Abstract: Accurate measurement of the position of features in an image is subject to a fundamental compromise: the features must be both small, to limit the effect of non-linear distortions, and large, to limit the effect of noise and discretization. This constrains both the accuracy and the robustness of image measurements, which play an important role in geometric camera calibration as well as in all subsequent measurements based on that calibration. In this paper, we present a new geometric camera calibration technique that exploits the complete camera model during the localization of control markers, thereby abolishing the marker size compromise. Large markers allow a dense pattern to be used instead of a simple disc, resulting in a significant increase in accuracy and robustness. When highly planar markers are used, geometric camera calibration based on synthetic images leads to true errors of 0.002 pixels, even in the presence of artifacts such as noise, illumination gradients, compression, blurring and limited dynamic range. The camera parameters are also accurately recovered, even for complex camera models.
Damien Douxchamps, Yannick Verschueren, Sébastien Lugan, Laurence Mutuel, Benoît Macq and Kunihiro Chihara, On-board axial detection of wake vortices using a 2µm LiDAR, IEEE Trans. on Aerospace and Electronic Systems, Vol. 44, No. 4, Oct. 2008, pp.1276-1290. BibTeX, PDF
Abstract: This paper describes the first successful attempt to detect wake vortices axially using an on-board infra-red pulsed Doppler LiDAR (Light Detection And Ranging). On-board axial detection is more complex than the classic ground-based tangential approach, because the axial air speed in vortices is low and the atmospheric particle density is reduced, yielding a poorer SNR. To provide meaningful results in such unfavourable conditions we have developed a new flexible signal processing method based on a two-primitive model fitting the spectrum of the Doppler return. This new spectral estimation successfully detects wake vortices with an admissible SNR that is lower than other on-board state-of-the-art approaches. It was validated through flight tests.
Damien Douxchamps, Hervé Capart, Dimitri Devriendt and Christophe Craeye, Three-dimensional reconstruction of the oscillatory free-surfaces of a flow over antidunes: stereoscopic and velocimetric techniques, Experiments in Fluids, Vol. 39, No. 3, Springer-Verlag, Sep. 2005, pp.535-553. BibTeX, PDF
Abstract: Imaging methods developed to characterise the oscillatory free surface of rapid fows are presented and applied to torrential currents over sediment antidunes. The aim is to obtain high-resolution relief maps of the free surface topography. Two measurement principles are tested, both based on the imaging of floating tracers dispersed on the rapidly fowing surface. The first technique involves direct stereoscopic measurements. The second technique is indirect, and exploits a Bernoulli relation to derive surface elevations from the horizontal velocity field acquired using a single camera. Special attention is paid to error estimation and control. Relief maps obtained for various bedform patterns are presented, allowing comparison between the two techniques.

Thesis

Damien Douxchamps, Multidimensional Photogrammetry of Short-Lived Events, Université catholique de Louvain, Louvain-la-Neuve, Belgium, Oct. 2004, Thèse de Doctorat. BibTeX, PDF
Abstract: This thesis presents a collection of photogrammetry techniques aimed at the analysis of short-lived events. The small time scale on which these phenomena happen makes them difficult to capture not only from the point of view of hardware but also because one can not obtain several measurements of events that are not repeatable. Three subjects are presented in ascending order of complexity. A simple unidimensional image sensor for solids opens the discussion followed by a set of video cameras for liquid flows measurements and finally a full three-dimensional data set of the atmosphere is analysed. A study of perspective distortions in three dimensional image matching which did not fit in this scope is presented in the Appendix.
Damien Douxchamps, Stereometric Reconstruction of the Free Surface Associated to a Flow over Three-Dimensional Antidunes, Université catholique de Louvain, Louvain-la-Neuve, Belgium, Jun. 1998, Maitrise. BibTeX, PDF
Abstract: The present report describes digital imaging techniques aimed at the experimental characterization of the free surface of a flow propagating over three-dimensional antidunes. Direct methods exist for the recovery of water surfaces, like resistive gauges. However, the unstable aspect of the flow we analyze is a source of great sensitivity to intruding objects. Our study will therefore focus on a non-invasive technique based on stereometry to recover the fluid surface from digital images of the flow. Another independent analysis based on velocimetric measurements was conducted simultaneously. It is subject to a parallel discussion in [7]. The collaboration of the Civil Engineering Department and the Telecommunications and Remote Sensing Department will make a cross-validation of both approaches possible, and hence provide a certain insurance in the quality of our results.

Conference papers

D.Douxchamps and J.G.Hale, True Multi-Touch Displays: What, How and Why, Intl. Display Workshop (IDW 2011), Nagoya, Japan, Dec. 7-9, 2011, invited paper. BibTeX, PDF
Abstract: The characteristic feature of a true multi-touch display is the handling of a large number of interaction points. In this short discussion, we describe how these displays work, why they are ideally suited for large multi-user systems and what kinds of new user-experience they facilitate.
Nick Campbell and Damien Douxchamps, ''The Listening Eye'': a non-verbal sensing device for interactive systems, International Conference on Affective Computing and Intelligent Interaction (ACII 2007), Lisbon, Portugal, Sep. 12-14, 2007. BibTeX, PDF
Nick Campbell and Damien Douxchamps, Processing Image and Audio Information for Recognising Discourse Participation Status, Interspeech Conference (IS 2007), Antwerp, Belgium, Aug. 27-31, 2007. BibTeX, PDF
Abstract: This paper describes a system based on a 360-degree camera with a single microphone that detects speech activity in a round table context for the purpose of estimating discourse participation status information for each member present. We have obtained 97% accuracy in detecting participants and have shown that the use of non-verbal and back-channel speech information is a useful indicator of participant status in a discourse.
Sébastien Lugan, Laurent Bricteux, Benoît Macq, Piotr Sobieski, Grégoire Winckelmans and Damien Douxchamps, Simulation of LIDAR-Based Aircraft Wake Vortex Detection Using a Bi-Gaussian Spectral Model, IEEE International Geoscience and Remote Sensing Symposium (IGARSS 2007), Barcelona, Spain, Jul. 23-27, 2007. BibTeX, PDF
Abstract: A new spectral model of the return signal from a LIDAR Doppler wake vortex detector is proposed. It has been experimentally discovered during ground-based and flight test campaigns but suffered a lack of theoretical evidence. Using high resolution fluid simulations of wake vortices, we highlight the physical meaning of this model. Comparisons with the traditional single Gaussian model show the superiority of this new approach is consistent with previous experimental results.
Damien Douxchamps and Nick Campbell, Robust Real-Time Face Tracking for the Analysis of Human Behaviour, Lecture Notes in Computer Sciences (LNCS), Vol. LNCS 4892, eds. Popescu-Belis, Renals, Bourlard, Springer-Verlag, 4th Joint Workshop on Multimodal Interaction and Related Machine Learning Algorithms (MLMI 2007), Brno, Czech Republic, Jun. 28-30, 2007, pp.1-10, invited paper. BibTeX, PDF
Abstract: We present a real-time system for face detection, tracking and characterisation from omni-directional video. Viola-Jones is used as a basis for face detection, then various filters are applied to eliminate false positives. Gaps between two detection of a face by the Viola-Jones algorithms are filled using a colour-based tracking. This system reliably detects more than 97% of the faces across several one-hour videos of unconstrained meetings, both indoor and outdoor, while keeping a very low false-positive rate (<0.5%) and without changes in parameters. Diverse measurements such as head motion and body activity are extracted to provide input to further research on human behaviour and for tracking participant activities at round-table meetings and similar discourse environments.
Damien Douxchamps, Benoît Macq and Kunihiro Chihara, High accuracy traffic monitoring using road-side line-scan cameras, IEEE Intelligent Transportation Systems Conference (ITSC 2006), Toronto, Canada, Sep. 17-21, 2006. BibTeX, PDF
Abstract: This paper presents a new technique for simultaneous traffic monitoring and law enforcement using a roadside rig head based on two line-scan cameras. As the vehicle travels across the vertical scanning lines, two images are formed and can be correlated with each other to determine the vehicle speed. Our first tests showed that the resulting videos are easily interpreted by computers in real-time and that the measures are both accurate (less than 1% error) and stable. In addition to speed, the system is able to extract a broad range of traffic information, among others the vehicle size, acceleration and inter-vehicle distances.
Nick Campbell, Toshiyuki Sadanobu, Masataka Imura, Naoto Iwahashi, Suzuki Noriko and Damien Douxchamps, A Multimedia Database of Meetings and Informal Interactions for Tracking Participant Involvement and Discourse Flow, Fifth International Conference on Language Resources and Evaluation (LREC 2006), Genoa, Italy, May 22-28, 2006. BibTeX, PDF
Abstract: At ATR, we are collecting and analysing meetings data using a table-top sensor device consisting of a small 360-degree camera surrounded by an array of high-quality directional microphones. This equipment provides a stream of information about the audio and visual events of the meeting which is then processed to form a representation of the verbal and non-verbal interpersonal activity, or discourse flow, during the meeting. This paper describes the resulting corpus of speech and video data which is being collected for the above research. It currently includes data from 12 monthly sessions, comprising 71 video and 33 audio modules. Collection is continuing monthly and is scheduled to include another ten sessions.
Damien Douxchamps and Benoît Macq, Integrating perspective in stereo image matching, IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2004), Montreal, Canada, May 17-21, 2004. BibTeX, PDF
Abstract: This paper introduces a correlation-based method for the three-dimensional reconstruction of scenes from a multi-camera imaging system. Our technique is to cast the matching and reconstruction problems into a single 3D process that uses perspective distortions to directly retrieve, in a dense fashion, the 3D planes locally tangent to the scene. Avoiding image assumptions like fronto-parallelism, block shapes, perspective distortion models or camera models, our method only needs a local planarity hypothesis of the scene.
Damien Douxchamps, Xavier Marichal, Toshiyuki Umeda, Pedro Correa Hernandez and Fernando Marques, Automatic body analysis for mixed reality applications, 4th European Workshop in Image analysis for Multimedia Interactive Services (WIAMIS 2004), Lisboa, Portugal, Apr. 21-23, 2003, pp.423-426. BibTeX, PDF
Abstract: The present paper elaborates on specific techniques to improve the performance of a technical system that was designed and implemented by the IST-art.live project to offer multimedia authors the capacity of designing immersive interactive narratives involving real people into their own universe of pictures, graphics and associated designs. The resulting mixed-reality environments allow for the creation of stories that mix graphical elements with inputs from live cameras. When some users come in front of the cameras, they get themselves immersed within the visual ambiance and they are therefore involved within the narrative, which they are able to interact with through their gestures and behavior. The present paper introduces new results about the body analysis of the users and the interactive capabilities it provides: head, hands and feet of the users are detected and tracked thanks to geodesic distances with respect to the center of gravity of the segmented silhouettes and human morphological information.
Damien Douxchamps, Benoît Spinewine, Yves Zech and Benoît Macq, Particle-based imaging methods for the characterisation of complex fluid flows, Photomec 2002 workshop, Louvain-la-Neuve, Belgium, Feb. 20-21, 2003. BibTeX, PDF
Abstract: We review a set of particle-based imaging methods, so-called the Voronoi methods, for the three-dimensional characterisation of fluid-granular flows. The methods mainly involve positioning and tracking (PTV) of particles, dispersed either on the free surface or in the flow itself, in order to estimate local flow velocities and/or surface topography. Detection of particle centroids on digital images, stereoscopic reconstruction of 3D particle positions, and tracking on successive frames, form the core sections of the paper. The originality of the methods is to rely on the geometrical properties of the Voronoi diagram to perform stereo reconstruction and tracking even for the case of very dense and fluctuating dispersions, cases for which traditional PTV algorithms have shown their limitations. The capabilities and robustness of the methods are qualitatively illustrated on a wide range of 2D and 3D applications.
Xavier Marichal, Benoît Macq, Damien Douxchamps, Toshiyuki Umeda et al., The ART.LIVE architecture for mixed reality, International Virtual Reality Conference 2002 (IVRC 2002), Laval, France, Sep. 17-19, 2002, Special session on ''1st Virtual and Mixed Reality Projects''. BibTeX, PDF
Abstract: The goal of the art.live project was to develop an architecture and a set of tools, both generic and application dependent, for the enhancement of narrative spaces thanks to the production of a mixed-reality environment: the art.live architecture aimed at creating interactive stories that mix graphical elements with inputs from live cameras. The real impact of the system occurs when some persons are in front of the cameras: they get themselves immersed within the visual ambiance and they are therefore involved within the narrative, which they are able to interact with through their behavior. At the opposite side of the architecture, other persons are looking at screens where the mixed images are rendered and they might also be offered to interact with the system.
Xavier Marichal, Benoît Macq, Damien Douxchamps, Toshiyuki Umeda et al., Immersive interactive narratives, International Conference on Augmented, Virtual Environments and Three-Dimensional Imaging (ICAV3D 2001), Mykonos, Greece, May 30 - Jun. 1, 2001, pp.259-262. BibTeX, PDF
Abstract: The goal of the art.live project is to develop an architecture and a set of tools, both generic and application dependent, for the enhancement of narrative spaces thanks to the production of a mixed-reality environment. Having in mind the mixed-reality framework (as defined by Milgram in "A Taxonomy of Real and Virtual World Display Integration" [1], in Mixed Reality - Merging Real and Virtual Worlds, 1999, Ohmsha Ltd. and Springer-Verlag), the art.live architecture aims at creating narrative spaces, e.g. interactive stories, that mix graphical elements with live inputs of cameras. The real impact of the system occurs when some persons are in front of the cameras: they get themselves immersed within the visual ambiance and they are there- fore involved within the narrative, which they are able to interact with through their behavior. At the opposite side of the architecture, other persons are looking at screens where the mixed images are rendered and they might be offered to interact with the system.
Damien Douxchamps, David Ergo, Benoît Macq, Xavier Marichal et al., Immersive communication, Workshop on Image Analysis for Multimedia Interactive Services (WIAMIS 2001), Tampere, Finland, May 16-17, 2001. BibTeX, PDF
Abstract: An apparatus for communication/entertainment mixing synthetic and natural images in real-time is designed and allows the "user" to be captured through vision-based sensors, like (web) cameras. The composed visual scenes are to be experienced in physical spaces and/or to be viewed through web browsers. The word "transaction" has been coined to this interactive narrative system where users can interact with narrative machines (devices with computing power and containing databases of meaningful information).
Andrea Cavallaro, Damien Douxchamps, Touradj Ebrahimi and Benoît Macq, Segmenting moving objects: the MODEST video object kernel, Workshop on Image Analysis For Multimedia Interactive Services (WIAMIS 2001), Tampere, Finland, May 16-17, 2001. BibTeX, PDF
Abstract: An apparatus for communication/entertainment mixing synthetic and natural images in real-time is designed and allows the "user" to be captured through vision-based sensors, like (web) cameras. The composed visual scenes are to be experienced in physical spaces and/or to be viewed through web browsers. The word "transfiction" has been coined to this interactive narrative system where users can interact with narrative machines (devices with computing power and containing databases of meaningful information).
Xavier Marichal, Benoît Macq, Damien Douxchamps, Toshiyuki Umeda et al., Immersive interactive narratives, International Conference on Media Futures (ICMF2001), Florence, Italy, May 8-9, 2001. BibTeX, PDF
Abstract: The goal of the art.live project is to develop an architecture and a set of tools, both generic and application dependent, for the enhancement of narrative spaces thanks to the production of a mixed-reality environment. Having in mind the mixed-reality framework (as defined by Milgram in A Taxonomy of Real and Virtual World Display Integration , in Mixed Reality - Merging Real and Virtual Worlds, 1999, Ohmsha Ltd. and Springer-Verlag), the art.live architecture aims at creating narrative spaces, e.g. interactive stories, that mix graphical elements with live inputs of cameras. The real impact of the system occurs when some persons are in front of the cameras: they get themselves immersed within the visual ambiance and they are therefore involved within the narrative, which they are able to interact with through their behavior. At the opposite side of the architecture, other persons are looking at screens where the mixed images are rendered and they might be offered to interact with the system.
Toshiyuki Umeda, Damien Douxchamps, Xavier Wielemans, Alok Nandi and Xavier Marichal, Real-time interactive immersion, International Symposium on Mixed Reality (ISMR 2001), Yokohama, Japan, Mar. 14-15, 2001, pp.177-178. BibTeX
Bruno Abreu, Luis Botelho, Andrea Cavallaro, Damien Douxchamps, P. Figueiredo, Benoît Macq, Benoît Mory, Luis Nunes, Javier Orri, Maria-Jose Trigueiros and A. Violante, Video-Based Multi-Agent Traffic Surveillance System, Intelligent Vehicles 2000 Conference (IV 2000), Detroit, USA, Oct. 3-5, 2000, pp.457-462. BibTeX, PDF
Abstract: This paper describes Monitorix, a video-based traffic surveillance multi-agent system. Monitorix agents are grouped in four tiers, according to the kind of information processing they perform: the sensors and effectors tier, the objective description tier, the application assistant tier, and the user assistant tier. The video analysis algorithms use an adaptive, data-driven, application independent approach to extract features from the video raw data. In spite of the diversity of agent tasks, adaptive learning algorithms are used in most cases. The integration of video analysis algorithms and agent technology is made via a special middle agent called Proxy. Monitorix is a fully decentralised multi-agent system living in a FIPA Platform and using FIPA Agent Communication Language. The Tracking of vehicles across non-overlapping cameras is performed by the Tracker agent, using a traffic model and learning algorithms that tune the model parameters.
Damien Douxchamps, Hervé Capart, Dimitri Devriendt and Christophe Craeye, Three-dimensional reconstruction of the oscillatory free-surfaces of a flow over antidunes: stereoscopic and velocimetric techniques, OCEANS 2000 MTS/IEEE Conference, Vol. 3, Providence, USA, Sep. 11-14, 2000, pp.1535-1542. BibTeX, PDF
Abstract: We present imaging methods developed to characterize the oscillatory free-surface of rapid flows and apply them to torrential currents propagating over sediment antidunes. The aim is to obtain high-resolution relief maps of the free-surface topography, in order to highlight the regular spatial patterns associated with the bedforms. Two measurement principles are outlined and tested, both based on the imaging of floating tracers dispersed on the rapidly flowing surface. The first relies on direct stereoscopic measurements obtained using two cameras, while the second exploits an original velocimetric principle allowing to derive elevation from the velocity field acquired using a single camera. The measurement procedures and image analysis algorithms are introduced for the two methods, along with the physical assumptions underlying the velocimetric principle. The results of the two techniques are compared for different free-surface patterns and good correspondence is obtained. The obtained relief maps vividly depict the variety of motifs that can evolve as a result of interaction between shallow flows and loose sediment beds.
Patrick Piscaglia, Andrea Cavallaro, Michel Bonnet and Damien Douxchamps, High Level Description of Video Surveillance Sequences, Lecture Notes in Computer Science, Vol. LNCS 1629, eds. Helmut Leopold, Narciso N. García, Springer, 4th European Conference on Multimedia Applications, Services and Techniques (ECMAST 99), Madrid, Spain, May 26-28, 1999, pp.316-331. BibTeX, PDF
Abstract: One of the goals of the ACTS project MODEST is to build an automatic video-surveillance system from a sequence of digital images. The overall system can be divided into the following sub-tasks which are of great interest in the representation of images, namely the automatic segmentation of the video-surveillance sequences, and the extraction of descriptors (such as those in MPEG-7) to represent the objects in the scene and their behaviors.
Dimitri Devriendt, Damien Douxchamps, Hervé Capart, Christophe Craeye, Benoît Macq and Yves Zech and Christophe Craeye Benoît Macq and Yves Zech, Three-dimensional reconstruction of a periodic free surface from digital imaging measurements, Advances in Fluid Mechanics II, Vol. 21, eds. M.Rahman, M. Comini, C.A. Brebbia, Computational Mechanics Publications, WIT Press, Second International Conference on Advances in Fluid Mechanics, Udine, Italy, May 13-15, 1998, pp.203-212. BibTeX, PDF
Abstract: We report on imaging techniques aimed at the three-dimensional characterisation of a fast-flowing free surface. The flow considered is a shallow-water current propagating over a gradually varied train of antidunes. Nearly periodic surface waves develop as a result of interaction with the three-dimensional bedforms. The topography of the flow free surface constitutes the primary interest. Two measurement techniques are presented, one direct based on stereovision, and one indirect based on velocimetry and fluid mechanical constraints. Preliminary results obtained using the two techniques are compared. Both methods are shown to yield free-surface geometries at resolutions much higher than those attainable using conventional gauges.

Photography

Damien Douxchamps - photo, Jaakko Hyry - text, Sumon salaisuudet, in Asiakaslehti X (circulation 200.000), Veikkaus, Finland, July 2007, pp.16-21 + cover. WWW