A geometric model is proposed for an artificial foveal vision system, and its plausibility in the context of biological vision is explored. The model is based on an isotropic, scale invariant two-form that describes the spatial layout of receptive fields in the the visual sensorium (in the biological context roughly corresponding to retina, LGN, and V1). It overcomes the limitation of the famil...

Implicit surfaces are becoming increasingly popular in geometric modeling. Procedurally defined implicit surfaces, in particular surfaces built around skeletons, provide an intuitive representation for many natural objects, and objects commonly used in geometric modeling. This paper presents several techniques that provide good control over the way different skeletally defined implicit surfaces...

It is my pleasure and a great honor to introduce this IJCISIM Special Issue on Computer Graphics and Geometric Modeling based on (but not confined to) the papers accepted for the “Sixth International Workshop on Computer Graphics and Geometric Modeling CGGM’2007” held at the Graduate University of the Chinese Academy of Sciences, Beijing (China), May 27-3

This paper is concerned with various aspects of the modeling of parallel curves on surfaces with special emphasis on surfaces of revolution. An algorithm for efficient tracking of the geodesics on these surfaces is presented. Existing methods for plane offset curves are adapted to generate G-spline approximations of parallel curves on arbitrary surfaces. An algorithm to determine singularities ...

The aim of this paper is to make progress towards a geometric model theory for non first order theories. The main difficulty is to work in an environment where the compactness theorem fails. This paper continues the work started in [GrLel]. The main result is an axiomatic approach to the Hrushovski-Zilber group configuration theorem.

We present a method for navigating in geometric models and enrich them with structure and context information. We offer dedicated views for this information, develop strategies to navigate in them and focus on the tight coupling between manipulations in these views. This coupling means that information in one view is emphasized in another view and requires an analysis of visibility and recogniz...

Mobile instantaneous messaging (MIM) services significantly facilitate personal and business communications, inevitably consume substantial network resources, and potentially affect the network stability. In this paper, we aim to understand the traffic nature of MIM in cellular networks. Specifically, in order to reach credible conclusions, our research takes account of practical measurement re...

The exact knowledge of the blood vessel geometry plays an important role, not only in clinical applications (stroke diagnosis, detection of stenosis), but also for detailed analysis of functional data, such as fMRI or optical imaging data. Here we focus on validating not only the geometry of the extracted vascular pattern, but also its function, namely the fluid dynamics. For validating angiogr...

the time-optimal trajectory for an airplane from some starting point to some final point is studied by many authors. here, we consider the extension of robot planer motion of dubins model in three dimensional spaces. in this model, the system has independent bounded control over both the altitude velocity and the turning rate of airplane movement in a non-obstacle space. here, in this paper a g...

This paper describes a method for calibrating a pan-tilt camera head. The key feature of the method is that the camera, the pan-tilt unit, and the relationship between the camera and the pan-tilt unit, are calibrated independently. This paper develops a geometric model of the pan-tilt camera head and presents procedures to estimate the values of the unknown model parameters. Target image reposi...