Perceptual user interfaces promise modes of fluid computer-human interaction that complement the mouse and keyboard, and have been especially motivated in non-desktop scenarios, such as kiosks or smart rooms. Such int...
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Perceptual user interfaces promise modes of fluid computer-human interaction that complement the mouse and keyboard, and have been especially motivated in non-desktop scenarios, such as kiosks or smart rooms. Such interfaces, however, have been slow to see use for a variety of reasons, including the computational burden they impose, a lack of robustness outside the laboratory, unreasonable calibration demands, and a shortage of sufficiently compelling applications. We have tackled some of these difficulties by using a fast stereo vision algorithm for recognizing hand positions and gestures. Our system uses two inexpensive video cameras to extract depth information. This depth information enhances automatic object detection and tracking robustness, and may also be used in applications. We demonstrate the algorithm in combination with speech recognition to perform several basic window management tasks, report on a user study probing the ease of using the system, and discuss the implications of such a system for future user interfaces.
Sequential Monte Carlo (SMC) methods have in recent years been applied to handle some of the problems inherent to model-based tracking. In this paper we suggest to apply bootstrapping to reduce the required number of ...
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In most, if not all fast marching methods published hitherto, the input cost function and the output arrival time are sampled on exactly the same grid. But since the input data samples are differences of the output sa...
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This paper presents a method for detection of homogeneous regions in grey-scale images, representing them as blobs. In order to be fast, and not to favour one scale over others, the method uses a scale pyramid. In con...
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The recognition of script in historical documents requires suitable techniques in order to identify single words. Segmentation of lines and words is a challenging task because lines are not straight and words may inte...
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This paper deals with an absolute mobile robot self-localization algorithm in an indoor environment. Until now, localization methods based on conical omnidirectional vision sensors uniquely used radial segments from v...
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This paper deals with an absolute mobile robot self-localization algorithm in an indoor environment. Until now, localization methods based on conical omnidirectional vision sensors uniquely used radial segments from vertical environment landmarks projection. The main motivation of this work is to demonstrate that the SYCLOP sensor can be used as a vision sensor rather than a goniometric one. We will show how the calibration allows us to know the omnidirectional image formation process to compute a synthetic image base. Then, we will present the spatial localization method using a base of synthetics images and one real omnidirectional image. Finally, some experimental results obtained with real noisy omnidirectional images are shown.
In applications of egomotion estimation, such as real-time vision-based navigation, one must deal with the double-edged sword of small relative motions between images. On one hand, tracking feature points is easier, w...
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In applications of egomotion estimation, such as real-time vision-based navigation, one must deal with the double-edged sword of small relative motions between images. On one hand, tracking feature points is easier, while on the other, two-view structure-from-motion algorithms are poorly conditioned due to the low signal-to-noise ratio. In this paper, we derive a multi-frame structure from motion algorithm for calibrated central panoramic cameras. Our algorithm avoids the conditioning problem by explicitly incorporating the small baseline assumption in the algorithm's design. The proposed algorithm is linear, amenable to real-time implementation, and performs well in the small baseline domain for which it is designed.
Preserving cultural heritage and historic sites is an important problem. These sites are subject to erosion, vandalism, and as long-lived artifacts, they have gone through many phases of construction, damage and repai...
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Preserving cultural heritage and historic sites is an important problem. These sites are subject to erosion, vandalism, and as long-lived artifacts, they have gone through many phases of construction, damage and repair. It is important to keep an accurate record of these sites using 3-D model building technology as they currently are, so preservationists can track changes, foresee structural problems, and allow a wider audience to "virtually" see and tour these sites. Due to the complexity of these sites, building 3-D models is time consuming and difficult, usually involving much manual effort. This paper discusses new methods that can reduce the time to build a model using automatic methods. Examples of these methods are shown in reconstructing a model of the Cathedral of Saint-Pierre in Beauvais, France.
This paper describes a method for colour texture analysis, which performs segmentation based on colour and texture information. The main goal of this approach is to examine the contribution of chromaticity features in...
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The current state-of-the-art for egomotion estimation with omnidirectional cameras is to map the optical flow to the sphere and then apply egomotion algorithms for spherical projection. In this paper, we propose to ba...
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The current state-of-the-art for egomotion estimation with omnidirectional cameras is to map the optical flow to the sphere and then apply egomotion algorithms for spherical projection. In this paper, we propose to back-project image points to a virtual curved retina that is intrinsic to the geometry of the central panoramic camera, and compute the optical flow on this retina: the so-called back-projection flow. We show that well-known egomotion algorithms can be easily adapted to work with the back-projection flow. We present extensive simulation results showing that in the presence of noise, egomotion algorithms perform better by using back-projection flow when the camera translation is in the X-Y plane. Thus, the proposed method is preferable in applications where there is no Z-axis translation, such as ground robot navigation.
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