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Journals and Conferences
In this paper, we present the project Urbi et Orbi, a framework to dynamically manage distributed virtual environments (DVEs). This framework relies on a dedicated scripting language, Goal, which is typed, object-oriented and dynamically bound. Goal is interpreted by the application hosted by each machine and is designed to handle efficiently both network… (More)
SUMMARY This paper presents an experiment with the synchronous approach to reactive systems programming, and particularly the Signal language, applied to a signiicant problem in robot vision: active visual reconstruction. This application consists of the speciication of a system dealing with various domains such as robot control, computer vision and… (More)
In a radial gradient, the refractive index profile is normally represented by a polynomial with only even powers of r. If, however, odd powers of r are present in the representation, the effect on aberrations can be serious. A Wood lens serves as an example.
Analytic ray-tracing formulas provide a rapid means of tracing rays, including skew rays, in a radial gradient. A fifth-order formula for the ray position and direction and a fourth-order formula for the optical path length give sufficiently accurate results for various applications.
In Distributed Virtual Environments, each machine equally handles the communications over the network, provides the user with a view of the world, and processes her requests. A major issue is to ensure that the network communication does not hinder the interactivity between the machine and the user. In this paper, we present a program designed to achieve… (More)
For a space rendezvous mission, autonomy imposes stringent performance requirements regarding navigation, for the guidance and control to be managed. For the final phase of the rendezvous, a vision-based navigation, using a monocular camera, can be a solution. Markerless 3D model-based tracking has been studied and tested on a mock-up of a telecommunication… (More)
Expressions are derived for computing the mean and variance of the number of renewals in observation times of any length and for any values of the scaling parameter of the censored Poisson process. These results depend on certain identities involving the complex roots of unity. Computations show the oscillatory behavior to be expected when the average… (More)
This introduction briefly defines the scope of the feature in this 1 Oct. 1990 issue on gradient-index image systems and discusses where the field is going. The second part of the feature, on microoptics, will appear in an issue later this year. All papers are based on presentations made at the joint symposium MOC/GRIN'89.