In this paper, we describe a new optical tracker algorithm for the tracking of interaction devices in virtual and augmented reality. The tracker uses invariant properties of marker patterns to efficiently identify and reconstruct the pose of these interaction devices. Since invariant properties are sensitive to noise in the 2D marker positions, an off-line training session is used to determine ...

Since a few years, scenario based requirements engineering approaches have gained in popularity. Textual scenarios are narrative descriptions of flows of actions between agents. They are often proposed to elicit, validate or document requirements. The CREWS experience has shown that the advantage of scenarios is their easiness of use, and that their disadvantage stands in the lack of guidelines...

Images are formed as projections of the three-dimensional world onto a two-dimensional light-sensing surface. The brightness of the image at each point indicates how much light was absorbed by the surface at that spatial position at a particular time (or over some interval of time). When an object in the world moves relative to the sensor surface, the two-dimensional projection of that object m...

Many kinds of computer vision problems can be formalized as statistical estimation problems with nuisance parameters. In the past, such problems have been solved without making any distinction between the nuisance parameters and structural ones. However, a theory of statistics suggests that eliminating the nuisance parameters by assuming a probability distribution on them improves estimation ac...

This paper presents two variations of a Hough-voting framework used for action recognition and shows classification results for lowresolution video and videos depicting human interactions. For low-resolution videos, where people performing actions are around 30 pixels, we adopt low-level features such as gradients and optical flow. For group actions with human-human interactions, we take the pr...

In most imaging devices (including the human eye), the mechanisms that govern the projection of a 3D scene onto a 2D surface render the extraction of useful 3D information difficult. We investigate the effects of perspective on optic flow in a driver assistance application in which a camera is mounted on the wing mirror in order to observe a driver’s so called ‘blind spot’. A car travelling tow...

One of the difficulties in estimating optical flow is bias. Correcting the bias using the classical techniques is very difficult. The reason is that knowledge of the error statistics is required, which usually cannot be obtained because of lack of data. In this paper, we present an approach which utilizes color information. Color images do not provide more geometric information than monochromat...

This note describes two different methods for motion segmentation from optical flow. In the first method, the Jacobian matrix of the first spatial derivatives of the components of optical flow is used to compute the amount of uniform expansion, pure rotation, and shear at every flow point. In the second description, local properties of optical flow which are invariant for non-singular linear tr...

This paper presents a method for fast calculation of the egomotion done by a robot using visual features. The method is part of a complete system for automatic map building and Simultaneous Location and Mapping (SLAM). The method uses optical flow in order to determine if the robot has done a movement. If so, some visual features which do not accomplish several criteria are deleted, and then th...